# Analyses of the Effects of Global Change on Human Health and Welfare and Human Systems

Final Report, Synthesis and Assessment Product 4.6

U.S. Climate Change Science Program And the Subcommittee on Global Change Research

Convening Lead Author Janet L. Gamble, Ph.D., U.S. Environmental Protection Agency

Lead Authors 1
Kristie L. Ebi, Ph.D., ESS LLC. Anne E. Grambsch, U.S. Envir onmental Protection Agency Frances G. Sussman, Ph.D., Environ mental Economics Consulting Thomas J. Wilbanks, Ph.D., Oak Ridge National Laboratory

1 Contributing authors are acknowledged in individual chapters.SAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems



### FEDERAL EXECUTIVE TEAM

Acting Director, Climate Change Science Program: William J. Brennan

Director, Climate Change Science Program Office: Peter A. Schultz

Lead Agency Principal Representative to CCSP, National Program Director for the Global Change Research Program, U.S. Environmental Protection Agency: Joel D. Scheraga

Product Lead, Global Change Research Program, U.S. Environmental P rot ection Agency: Janet L. Gamble

Chair, Synthesis and Assessment Product Advisory Group Associate Director, National Center for Environmental Assessment, U.S. Environm ental Prot ection Agency: Michael W. Slimak

Synthesis and Assessment Product Coordinator, Climate Change Science Program Office: Fabien J.G. Laurier

Special Advisor, National Oceanic and Atmospheric
Administration Chad A. McNutt



### EDITORIAL AND PRODUCTION TEAM

Editor, U.S. Environmental Protection Agency: Janet Gamble
Technica l Editor, ICF International: Melinda Harr is Technical Editor, ICF Inte rnational: Toby Krasney Reference Coordinator, ICF International: Paul Stewart Reference Coordinator, ICF Inte rnational: Dylan Harrison-Atlas Reference Coordinator, ICF International: Sarah Shapiro Logistical and Technical Support, ICF International: Lauren Sm ith

iiSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems

Disclaimer: This document, part of the Synthesis and Assessment Produc ts described in the U.S. Climate Cha nge Science Program (CCSP) Strategic Plan, was prepared in accordance with Section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Public Law 106-554) and the information quality act guidelines issued by the U.S. Environmental Protection Agency pursuant to Section 515. The CCSP Interagency Committee relies on U.S. Environmental Protection Agency certifications regarding comp liance with S ection 515 and Agency guidelines as the basis for determining that this product conf orms with Section 515. For purposes of compliance with Section 515, this CCSP Synthesis and Assessment Product is an “interpreted product” as that te rm is used in U.S. Environmental Protection Agency guidelines and is classified as “highly influential”. This document does not express any regulatory policies of the United States or any of its agencies, or provides recommendations for regulatory action.

iiiJuly 2008

Members of Congress:

On behalf of the National Science and Technology Council, the U.S. Climate Change Science Program (CCSP) is pleased to transmit to the President a nd the Congress this Synthesis and Assessment Product (SAP), Analyses of the Effects of Global Change on Human Health and Welfare and Human Systems

. This is part of a series of 21 SAPs produced by the CCSP aimed at providing current assessments of climate change science to inform public debate, polic y, and operational decisions. These SAPs are also intended to help the CCSP develop future program resear ch priorities. This SAP is issued pursuant to Section 106 of the Global Change Research Act of 1990 (Public Law 101-606).

The CCSP’s guiding vision is to provide the Nation and the global community with the science-based knowledge needed to manage the risks and capture the opportunities associated with climate and related environmental changes. The SAPs are important steps toward achieving that vision and help to translate the CCSP’s extensive observational and research database into informational tools that directly address key questions being asked of the research community.

This SAP focuses on the effects of global change on hu man health and welfare and human systems. It was developed with broad scientific input and in accordance with the Guidelines for Producing CCSP SAPs, the Federal Advisory Committee Act, the Info rmation Quality Act, Section 515 of the Treasury and General Government Appropr iations Act for fiscal year 2001 (Public Law 106-554), and the guidelines issued by the Environmental Protection Agency pursuant to Section 515.

We commend the report’s authors for both the thorough na ture of their work and their adherence to an inclusive review process.

Sincerely,

Carlos M. Gutierrez Samuel W. Bodman John H. Marburger III Secretary of Commerce Secretary of Energy Director, Office of Science and Technology Policy Chair, Committee on Vice Chair, Committee on Executive Director, Committee Climate Change Science Climate Change Science on Climate Change Science and and Technology Integration and Technology Integration Technology Integration

ivSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems



### AUTHORS TEAM FO R THIS REPORT

Executive Summary Convening Lead Author: Janet L. Gamble, U.S. EPA
Lead Authors: Kristie L. Ebi, ESS LLC.; Frances G. Suss man, Environmental Economics Consulting; Thomas J. Wilbanks, Oak Ridge National Laboratory Contributing Authors: Colleen Reid, ASPH Fellow; John V.
Thom as, U.S. EPA; Christopher P. Weaver, U.S. EPA; Melinda Harris, ICF International; Randy Freed, ICF International Chapter 1 Convening Lead Author: Janet L. Gam ble, U.S. EPA
Lead Authors: Kristie L. Ebi, ESS LLC.; Anne Gram bsch, U.S. EPA; Frances G. Sussman, Environmental Economics Consulting; Thomas J. Wilbanks, Oak Ridge National Laboratory Contributing Authors: Colleen E. Reid, ASPH Fellow; Katharine Hayhoe, Texas Tech University; John V. Thoma s, U.S. EPA; Christopher P. Weaver, U.S. EPA Chapter 2 Lead Author : Kristie L. Ebi, ESS LLC. Contributing Authors: John Balbus, Environme ntal Defense; Patrick L. Kinney, Columbia University; Erin Lipp, University of Georgia; David Mills, Stratus Consulting; Marie S. O’Neill, University of Michigan; Mark Wilson, University of Michigan Chapter 3 Lead Author: Thom as J. Wilbanks, Oak Ridge National Laboratory Contributing Authors: Paul Kirshen, Tufts University; Dale Quattrochi, NASA/Marshall Space F light Cen ter; Patricia RomeroLankao, NCAR; Cynthia Rosenzwe ig, NASA/Goddard; Matthias Ruth, University of Maryland; W illiam Solecki, Hunter College; Joel Tarr, Carnegie Mellon University
Contributors: Peter Larsen, University of Alaska-Anchorage; Brian Stone, Georgia Tech Chapter 4 Lead Author: Frances G. Sussman, Environm ental Economics Consulting Contributing Authors: Maureen L. Cropper, University of Maryland at College Park ; H ector Galbraith, Galbraith Environmental Sciences LLC.; Da vid Godschalk, University of North Carolina at Chapel Hill; John Loomis, Colorado State University; George Luber, Ce nters for Disease Control and Prevention; Michael McGeehin, Ce nters for Disease Control and Prevention; James E. Neumann, Industrial Economics, Inc.; W. Douglass Shaw, Texas A&M University; Arnold Vedlitz, Texas A&M University; Sammy Zahran, Colorado State University Chapter 5 Convening Lead Author: Janet L. Ga mble, U.S. EPA
Lead Authors: Kristie L. Ebi, ESS LLC.; Frances G. Suss man, Environmental Economics Consulting; Thomas J. Wilbanks, Oak Ridge National Laboratory Contributing Authors: Colleen E. Reid, ASPH Fellow; John V. Thomas, U.S. EPA; Chr istopher P. Weaver, U.S. EPA

vSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems



### ACKNOWLEDGMENTS

This report has been peer reviewed in draft form by individuals iden tified for their diverse perspectives and technical expertise. The expert review and selection of reviewers followed the OMB’s Information Quality Bulletin for Peer Re view. The purpose of this independent review is to provide candid and critical comments that will assist the Climate Change Science Program in making this published report as sound as po ssible and to ensure that the report meets institutional standards. The p eer review comments, draft manus cript and response to the peer review comments are publicly available at : www.climatescience.gov/Library/sap/sap4- 6/default.php.

Environmental Protection Agency Internal Reviewers

We wish to thank the following individuals from the U.S. Environmental Protection Agency for
their rev iew of the first, and in some case later, draft(s) of the report. Reviewers from within EPA, included:

Lisa Conner Adam Daigneault Benjamin De Angelo Barbara Glenn Doug Grano Matthew Heberling Ju-Chin Huang Stephen Newbold Jason Samenow Sara Terry

National Center for Environmental Assessmen t, Global Ch ange Research Program

We extend our thanks to our colleagues in the Gl ob al Change Research Program who contributed thoughtful insights, reviewed nume rous drafts, and helped with the production of the report.

John Thomas Christopher Weaver

Federal Agency Reviewers

Likewise, we thank the reviewers from within th e federal “family.” Reviewers from across the federal agencies provided their comm ents during the public comment period.

Brigid DeCoursey Departme nt of Transportation Mary Gant National Instit utes of Environmental Health Sciences / NIH Indur M. Goklany Department of Interior Charlotte Skidmore Office of Management and Budget Samuel P. Williamson Office of the Federal Coordinator for Meteorology

Public Reviewers

We also extend our thanks to the reviewers who provided their commen ts during the public comment period, included individuals from the public.

William Fang Edison Electric Institute

viSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems

Katherine Farrell AACDH
Hans Martin Fuessel PICIR
Eric Holdsworth Edison Electric Institute
John Kinsman Edison Electric Institute
Kim Knowlton Natural Resources Defense Council Sabrina McCormick Michigan State University
J. Alan Roberson American Water Works Association
Gina Solomon Natural Resources Defense Council

Human Impacts of Climate Change Advisory Committee (HICCAC)

Finally, we are indebted to the thoughtful re view provided by a Federal Advisory Committee convened by the U.S. Environm ental Protection Agen cy to provide an independent expert review of the SAP 4.6. The panel (the Human Impacts of Climate Change Advisory Committee) met in
October 2007 to discuss their fi ndings and recommendations for the report. Following extensive revisions to the report, the HI CCAC reconvened by teleconference in January 2008 to review the authors’ response to comments. The panel’s review of the report has cont ributed to a markedly improved document.

Chair Tom Dietz Michigan State University
Co-chair Barbara Entwisle University of North Carolina
Members Howard Frumkin Center s for Disease Control and Prevention
Peter Gleick Pacific Institute Jonathan Patz University of Wisconsin Roger Pulwarty NOAA Eugene Rosa Washington State University Susan Stonich University of California at Santa Barbara

Thanks are also in order to Joanna Foellmer, the Designated Federal Off icial from within the
National Center for Environmental Assessmen t (NCEA) who organized and managed the
HICCAC.

ICF International

We thank our colleagues at ICF International for their support—logistical and technical—in preparing the report. We wish to extend special thanks to Melinda Ha rris and Randy Freed.

Summary

It has been an honor and a pleasure to work with all of the people name d above as well as the many colleagues we have encountered in the process of preparing this report. We hope that this document will be a positive step forward in our e fforts to assess the impacts of climate change on human systems and to evaluate opportunities for adaptation.

viiSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems



### RECOMMENDED CITATIONS Note: The page numbers included below are specific to the pre-layou t draft of the report. These page numbers will change in the final printed version.

For the Report as a Whole: CCSP, 2008: Analyses of the effects of global change on human health and welfare and human systems . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA.

For Executive Summary: Gamble, J.L., K.L. Ebi, F.G. Sussman, T.J. Wilbanks, C. Reid, J.V. Thom as, C.P. Weaver, M. Harris, and R. Freed, 2008: Executive Summary. In: Analyses of the effects of global change on human health and welfare and human systems . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. ES-1 to ES-14.

For Chapter 1: Gamble, J.L., K.L. Ebi, A. Grambsch, F.G. Sussman, T.J. W ilbanks, C.E. Reid, K. Hayhoe, J.V. Thomas, and C.P. Weaver, 2008:
Introduction. In: Analyses of the effects of global change on human health and welfare and human systems . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. 1-1 to 1-41. For Chapter 2: Ebi, K.L., J. Balbus, P.L. Kinney, E. Lipp, D. Mills, M.S. O’Neill, and M. W ilson, 2008: Effects of Global Change on Human Health.

In: Analyses of the effe cts of global change on human health and welfare and human systems

. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. 2-1 to 2-78.

For Chapter 3: Wilbanks, T.J., P. Kirshen, D. Quattrochi, P.

Rome ro-Lankao, C. Rosenzweig, M. Ruth, W. Solecki, and J. Tarr, 2008: Effects of Global Change on Human Settlements. In: Analyses of the effects of global change on human health and welfare and human systems . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. 3-1 to 3-31.

For Chapter 4: Sussman, F.G., M.L. Cropper, H. Galbraith, D. Godschalk, J. Loomis, G. Luber, M. McGeehin, J.E. Neum ann, W.D. Shaw, A. Vedlitz, and S. Zahran, 2008: Effects of Global Change on Human Welfare. In: Analyses of the effect s of global change on human health and welfare and human systems

. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. 4-1 to 4-74.

viiiSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems

For Chapter 5: Gamble, J.L., K.L. Ebi, F.G. Sussman, T.J. Wilbanks, C. Reid, J.V. Thomas, and C.P. Weaver, 2008: Common
Themes and Research Recommendations. In: Analyses of the effect s of global change on human health and welfare and human systems. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection Agency, Washington, DC, USA, p. 5-1 to 5-11.

ixSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems



### TABLE OF CONTENTS

Executive Summary
Abstract ES-3 ES.1 Climate Change and Vulnerability ES-3 ES.2 Climate Change and Human Health ES-5 ES.3 Climate Change and Human Settlements ES-7 ES.4 Climate Change and Human Welfare ES-9
ES.5 Tables ES-11

1. Introduction 1.1 Scope and Approach of the SAP 4.6 1-3 1.2 Climate Change in the United States: Cont ext for an Assessment of I mpacts on Human Systems 1-7 1.2.1 Rising temperatures 1-8 1.2.2 Trends in precipitation 1-9 1.2.3 Rising sea levels and eros ion of coastal zones 1-10 1.2.4 Changes in Extreme Conditions 1-11 1.3 Population Trends and Migratio n Patterns: A Context for Asse ssing Climate-related Im pacts
1-14 1.3.1 Trends in total U.S. Population 1-14 1.3.2 Migration patterns 1-15 1.4 Complex Linkages: The Role of Non-climate Factors 1-17
1.4.1 Econom ic status 1-18 1.4.2 Technology 1-18
1.4.3 Infrastructure 1-19 1.4.4 Human and Social Cap ital and Behaviors 1-20
1.4.5 Institutions 1-20 1.4.6 Interacting effects 1-21 1.5 Reporting Uncertainty in SAP 4.6 1-22
1.6 References 1-24
1.7 Tables 1-36 1.8 Figures 1-37

2. Human Health
2.1 Introduction 2-3
2.2 Observed Climate-Sensitive Health Outcomes in the United States 2-4
2.2.1 Thermal Extremes: Heat Waves 2-4
2.2.2 Thermal Extremes: Cold Waves 2-6 2.2.3 Extreme Events: Hurricanes, Floods, and Wildfires 2-6 2.2.4 Indirect Health Impact s of Climate Change 2-8 2.3 Projected Health Impacts of Climate Change in the United States 2-15 2.3.1 Heat-Related Mortality 2-15 2.3.2 Hurricanes, Floods, Wildfire s and Health Impacts 2-17
2.3.3 Vectorborne and Zoonotic Diseases 2-18

xSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems

2.3.4 Water- and Foodborne Diseases 2-18 2.3.5 Air Quality Morbidity and Mortality 2-19 2.4 Vulnerable Regions and Subpopulations 2-22 2.4.1 Vulnerable Regions 2-23 2.4.2 Specific Subpopulations at Risk 2-23 2.5 Adaptation 2-26 2.5.1 Actors and Their Roles and Responsibilities for Adaptation 2-27 2.5.2 Adaptation Measures to Manage Clim ate Change-Related Health Risks 2-29
2.6 Conclusions 2-29 2.7 Expanding the Knowledge Base 2-30
2.8 References 2-32
2.9 Boxes 2-57
2.10 Tables 2-61 2.11 Figures 2-72

3. Human Settlements
3.1 Introduction 3-3 3.1.1 Purpose 3-3 3.1.2 Background 3-3 3.1.3 Current State of Knowledge 3-4 3.2 Climate Change Impacts and the Vulner abilities of Huma n Settlements 3-4 3.2.1 Determinants of Vulnerability 3-4 3.2.2 Impacts of Climate Change on Human Settlements 3-5 3.2.3 The Interaction of Climate Imp acts with Non-Climate Factors 3-7 3.2.4 Realizing Opportunities from Climate Change in the United States 3-9 3.2.5 Examples of Impacts on Metropolitan Areas in the United States 3-10 3.3 Opportunities for Adaptation of Human Settlements to Climate Change 3-10 3.3.1 Perspectives on Adaptation by Settlements 3-11 3.3.2 Major Categories of Ad aptation Strategies 3-12 3.3.3 Examples of Current Adaptation Strategies 3-13 3.3.4 Strategies to Enhance Adaptive Capacity 3-14
3.4 Conclusions 3-14 3.5 Expanding the Knowledge Base 3-15
3.6 References 3-17
3.7 Boxes 3-24
3.8 Tables 3-29 3.9 Figures 3-31

4. Human Welfare
4.1 Introduction 4-3 4.2 Human Welfare, Well-being, and Quality of Life 4-4
4.2.1 Individual Measures of W ell-being 4-5 4.2.2 The Social Indicators Approach 4-6
4.2.3 A Closer Look at Communities 4-10 4.2.4 Vulnerable Populations, Co mmunities, and Adaptation 4-12 4.3 An Economic Approach to Human Welfare 4-13

xiSAP 4.6 Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems

4.3.1 Economic Valuation 4-15 4.3.2 Impacts Assessment and Monetary Valuation 4-16
4.3.3 Human Health 4-17 4.3.4 Ecosystems 4-22
4.3.5 Recreational Activitie s and Opportunities 4-28 4.3.6 Amenity Value of Climate 4-35
4.4 Conclusions 4-38 4.5 Expanding the Knowledge Base 4-39
4.6 References 4-41 4.7 Appendix 1 4-57
4.8 Boxes 4-64
4.9 Tables 4-66 4.10 Figures 4-72

5. Research 5.1 Synthesis and Assessment Product 4.6: Advances in the Science 5-3 5.1.1 Complex Linkages and a Cascading Chain of Im pacts Across Global Changes 5-3 5.1.2 Changes in Climate Extremes and Climate Averages 5-4 5.1.3 Vulnerable Populations and Vulnerable Locations 5-5 5.1.4 The Cost of and Capacity for Adaptation 5-6 5.1.5 An Integrative Framework 5-6 5.2 Expanding the Knowledge Base 5-7 5.2.1 Human Health Research Gaps 5-9 5.2.2 Human Settlements Research Gaps 5-10 5.2.3 Human Welfare Research Gaps 5-10

6. Glossary and Acronyms

xii

## Synthesis and Assessment Product 4.6

Analyses of the Effects of Global Change on Human
Health and W elfare and Human Systems

Executive Summary

Convening Lead Author: Janet L

. Gamble, U.S. Environmental Protection Agency

Lead Authors: Kristie L

. Ebi, ESS, LLC; Frances G. Sussman, Environmental Economics Consulting; Thomas J. Wilbanks, Oak Ridge National Laboratory

Contributing Authors : Colleen Reid , ASPH Fellow; John V. Thomas, U.S. Environmental Protection Agency; Christopher P. Weaver, U.S. Environmental Protection Agency; Melinda Harris, ICF International; Randy Freed, ICF International

ES-1SAP 4.6 Executive Summary

Table of Contents

Abstract .......................................................................................................................................................... 3

ES.1 Climate Change and Vuln erability .......................................................................................... ........... 3

ES.2 Climate Change and Human Health........................................................................................... ........ 5

ES.3 Climate Change and Human Settlements...................................................................................... ..... 7

ES.4 Climate Change and Human Welfare.......................................................................................... ....... 9

ES.5 Tables.................................................................................................................... ............................... 11

ES-2

### Abstract

Climate change, interacting with changes in land use and demographics, will affect important human dimensions in the United St ates, especially thos e related to human health, settlements and welfare. The challeng es presented by population growth, an aging population, migration patterns, and urban and coastal development will be affected by changes in temperature, precipitation, and ex treme climate-related events. In the future, with continued global warming, heat waves and heavy downpours are very likely to further increase in frequency and intensity. Co ld days and cold night s are very likely to become much less frequent over North Ameri ca. Substantial areas of North America are likely to have more frequent droughts of gr eater severity. Hurrican e wind speeds, rainfall intensity, and storm surge levels are likely to increase. Othe r changes include measurable
sea-level rise and increases in the occurren ce of coastal and riverine flooding. The United States is certainly capable of adapting to the collective impacts of climate change. However, there will still be certain indivi duals and locations wher e the adaptive capacity
is less and these individuals and their co mmunities will be disproportionally impacted by climate change.

This report – the Synthesis and Assessment Product 4.6 (SAP 4.6) – focuses on impacts of global climate change, especially impact s on three broad dimensions of the human condition: human health, human settlements, and human welfare. The SAP 4.6 has been prepared by a team of experts from academ ia, government, and the private sector in response to the mandate of the U.S. Climat e Change Science Program’s Strategic Plan (2003). The assessment examines potential im pacts of climate change on human society, opportunities for adaptation, and associated recommendations for addressing data gaps and near- and long-term research goals.



### ES.1 Climate Change and Vulnerability

Climate variability and change challenge even the world’s most advanced societies. At a very basic level, climate affects the costs of providing comfort in our homes and work places. A favorable climate can provide inpu ts for a good life: adequate fresh water supplies; products from the ranch, the farm, the forests, the rivers a nd the coasts; pleasure
derived from tourist destina tions and from nature, biodive rsity, and outdoor recreation. Climate not only supports the provision of ma ny goods and services, but also affects the spread of some diseases and the prevalence of ot her health problems. It is also associated
with threats from extreme even ts and natural disasters such as tropical storms, riverine and coastal flooding, wildfires, droughts, wind, hail, ice, heat, and cold.

This report examines the impacts on human society of global change, especially those
associated with clim ate change. The impact assessments in this report do not rely on specific emissions or climate change scenarios but, instead, rely on the existing scientific literature with respect to our understanding of climate cha nge and its impacts on human health, settlements and human well-being in the United States. Because climate change forecasts are generally not specific enough fo r the scale of local decision-making, this report adopts a vulnerability perspective in assessing impacts on human society.

ES-3SAP 4.6 Executive Summary

A vulnerability approach focuses on estimati ng risks or opportunities associated with possible impacts of clim ate cha nge, rather than on estimating (quantitatively) the impacts themselves which would require far more de tailed information about future conditions. Vulnerabilities are shaped not only by existing exposures, sensitivities, and adaptive capacities but also by responses to risks

. For example, Boston is generally more
vulnerable to heat waves than Dallas becau se there are fewer air-conditioned homes in Boston than in Dallas. At the same time, human responses ( e.g., the elderly not using airconditioning) also are an important determinant of impacts. This leads to our conclusion that climate change will result in regional differences in im pacts in the United States not only due to a regional pattern of changes in climate but the regional nature of our communities in adapting to these changes.

In the United States, we are observing the evidence of long-term ch anges in temp erature and precipitation consistent with global warming. Changes in average conditions are being realized through rising temperatures, ch anges in annual and seasonal precipitation, and rising sea levels. Observations also indi cate there are changes in extreme conditions, such as an increased frequency of heavy rain fall (with some increase in flooding), more heat waves, fewer very cold days, and an increase in areas affected by drought. There have been large fluctuations in the number of hurricanes from year to year which make it difficult to discern trends. Evidence suggests th at the intensity of A tlantic hurricanes and tropical storms has increased over the past few decades. However, changes in frequency are currently too uncertain for confident projection.

Changes in the size of the population, including especially sensitive sub-populations, and their geographic distribution across the landscape need to be accounted for when

assess ing climate variability and change impacts. According to the Census Bureau’s middle series projection, the US populati on will increase to some 570 million people. Moreover, the elderly population is increa sing rapidly and many health assessments identify them as more vulnerable than younge r age groups to a range of health impacts associated with climate change. Although numbers produced by population projections are important, nearly all trends point to mo re Americans living in areas that may be especially vulnerable to the effects of climate change. For example, many rapidly growing places in the Mountain West may al so experience decreased snow pack during winter and earlier spring melting, leading to lo wer stream flows, particularly during the high-demand period of summer. Similarly, coas tal areas are projected to continue to increase in population, with associated in creases in population de nsity, over the next
several decades.

Climate is only one of a number of global changes that affect huma n well-being. These non-climate processes and stresses interact with climate change, determining the overall severity of climate impacts. Socioecono mic factors that can influence exposures, vulnerability and impacts include population, economic status, technol ogy, infrastructure, human capital and social contex t and behaviors, and institutio ns. Trends in these factors alter anticipated impacts from climate because they fundamentally shape the nature and scope of human vulnerability. Understand ing the impacts of climate change and

ES-4SAP 4.6 Executive Summary

variability on the quality of life in the United States ther efore implies knowledge of how these factors vary by location, tim e, and socioeconomic group.

Climate change will seldom be the sole or primary factor determ ining a population’s or a location’s well-being. Ongoing adaptation al so can significantly influence climate impacts. For example, emergency warning systems have generall y reduced deaths and death rates from extreme events, while gr eater access to insurance and broader, government-funded safety nets for people struck by natural disasters have ameliorated the hardships they face. While this assessment focuses on how climate change could affect the future health, well-being, and settlement s in the United States, the extent of any impacts will depend on an array of non-clim ate factors and adaptive measures. Finally, the effects of climate change very often sp read from directly impacted areas and sectors to other areas and sectors through extensiv e and complex linkages. In summary, the importance of climate change depends on the directness of the climate impact coupled with demographic, social, economic, institut ional, and political factors, including, the degree of preparedness.

Consistent with all of the Synthesis and Assessme nt Products being prepared by the CCSP, this report includes statements regard ing uncertainty. Each chapter author team assigned likelihood judgments that reflect their assessment of the current consensus of the science and the quality and amount of evidence. The lik elihood terminology and the corresponding values that are used in this report are cons istent with the latest IPCC
Fourth Assessment and are furthe r explained in Chapter 1 of th is report. As the focus of this report is on impacts, it is important to note that these likelihood statements refer to the statement of the impact, not statements related to underlying climatic changes.

Table ES.1 provides examples of climate ch ange impacts that are id entified in the chapters for human health, settlements, and human welfare and includes potential adaptation strategies. The list of impacts is not comprehensive, but rather includes those that the available evidence suggest s may occur. It is important to note that not all effects have been equally well-studied. The effects identified for welfare, in particular, should be taken as examples of effects about whic h we have some knowledge, rather than a complete listing of all welfare effects.



### ES.2 Climate Change and Human Health

The United States is a highly developed count ry with a wide range of climates. While there may be fewer cases of illness and death associated with climate change in the
United States than in the deve loping world, we nevertheless anticipate increased costs to human health and well being. Greater wealth and a more developed public health system and infrastructure ( e.g., water treatment plants, sewers , and drinking water systems; roads, rails and bridges; flood control structures) will continue to enhance our capacity to respond to climate change. Similarly, governme nts’ capacities for disaster planning and emergency response are key assets that should allow the United States to adapt to many of the health effects associated with climate change.

ES-5SAP 4.6 Executive Summary

It is very likely that heat-related mo rbidity and mortality will increase over the coming decades. According to the U.S. Census, the U.S. population is aging; the percent of the population over age 65 is projected to be 13% by 2010 and 20% by 2030 (over 50 million people). Older adults, very young children, and persons with compromised immune systems are vulnerable to temperatur e extremes. This suggests that temperaturerelated morbidity and mortality are likely to increase. Similarly, heat-related mortality affects poor and minority populations disproport ionately, in part due to lack of air conditioning. The concentration of poverty in inner city neighborhoods leads to disproportionate adverse effects asso ciated with urban heat islands.

There is considerable speculation concerni ng the balance of c lim ate change-related decreases in winter mortality compared with increases in summer mortality. Net changes in mortality are difficult to estimate because , in part, much depends on complexities in the relationship between mortal ity and the changes associated with global change. Few studies have attempted to link the epidemiol ogical findings to climate scenarios for the United States, and studies that have done so have focused on the effects of changes in average temperature, with results dependent on climate scenarios and assumptions of future adaptation. Moreover, many factors c ontribute to winter mortality, making highly uncertain how climate change could affect mo rtality. No projections have been published for the U.S. that incorporate cr itical factors, such as the in fluence of influenza outbreaks.

The impacts of higher temperatures in urban areas and likely associated increases in tropospheric ozone concentrations can co ntribute to or exacerbate cardiovascu lar and pulmonary illness if current regu latory standards are not attained. In addition, stagnant air masses related to climate change are likely to degrade air quality in some densely populated areas. It is important to recognize that the United States has a welldeveloped and successful national regulatory program for ozone, PM2.5, and other criteria pollutants. That is, the influence of climate change on air quality will play out against a backdrop of ongoing regulatory control that will shift the baseline concentrations of air pollutants. Studies to date have typically held air pollutant emissions constant over future decades ( i.e., have examined the sensitivity of ozone concentrations to climate change rather than projecting actual future ozone concentrations). Physical features of communities, including housing quality and green space, soci al programs that affect access to health care, aspects of population composition (level of education, racia l/ethnic composition),
and social and cultural factors are all likel y to affect vulnerability to air quality.

Hurricanes, extreme precipitation resulting in floods, and wildfires also have the potential to affect public health thro ugh direct and indirec t health risks. SAP3.3
indicates that there is evidence for a hu m an contribution to increased sea surface temperatures in the tropical At lantic and there is a strong co rrelation to Atlantic tropical storm frequency, duration, and intensity. However, a confident assessment will require further studies. The health risks associated with such extreme events are thus likely to increase with the size of the population and th e degree to which it is physically, mentally, or financially constrained in its ability to prepare for and respond to extreme weather events. For example, coastal evacuations prompted by imminent hurricane landfall are only moderately successful. Many of those w ho are advised to flee to higher ground stay

ES-6SAP 4.6 Executive Summary

behind in inadequate shelter. Surveys find that the public is either not aware of the appropriate preventive actions or incorrectly assesses the extent of their personal risk.

There will likely be an increa se in the spread of sev eral food and w ater-borne pathogens among susceptible populations depending on the pathogens’ survival, persistence, habitat range and transmission under changing climate and
environmental conditions. While the United States has su ccessful programs to protect water quality under the Safe Drinking Wate r Act and the Clean Water Act, some contamination pathways and routes of e xposure do not fall under regulatory programs (e.g., dermal absorption from floodwaters, sw imming in lakes and ponds with elevated pathogen levels, etc.).The primary climate-re lated factors that affect these pathogens include temperature, precipitation, extreme w eather events, and shifts in their ecological regimes. Consistent with our understanding of climate change on human health, the impact of climate on food and water-borne pathogens will seldom be the only factor determining the burden of human injuries, illness, and death.

Health burdens related to climate change will vary by region. For the contin ental United States, the northern latitudes are likely to experience the largest increases in average temperatures; they will also bear the brunt of increases in ground-level ozone and other airborne pollutants. Because Midwestern and Northeastern citi es are generally not as well adapted to the heat as Southern cities, their popul ations are likely to be disproportionately affected by h eat related illnesses as heat waves increase in frequency, severity, and duration. The range of many vect ors is likely to extend northward and to higher elevations. For some vectors, such as rodents associated with Hantavirus, ranges are likely to expand, as the precipitation patterns under a warmer climate enhance the vegetation that controls the rodent populat ion. Forest fires w ith their associated decrements to air quality and pulmonary e ffects are likely to increase in frequency, severity, distribution, and duration in the Southeast, the Intermountain West and the

West. Table ES.2 summarizes regional vulnerabili ties to a range of climate impacts.

Finally, climate change is very likely to accentuate the disparities already evident in the American health care system. Many of the expected health effects are likely to fall disproportionately on the poor, the elderly, the disabled, a nd the uninsured. The most important adaptation to ameliorate health e ffects from climate change is to support and maintain the United States’ public health infrastructure.



### ES.3 Climate Change and Human Settlements

Effects of climate change on human se ttlements are likely to vary considerably according to location-specific vulnerabiliti es, with the most vulnerable areas likely to include Alaska with increased permafrost melt, flood-risk coastal zones and river basins, and arid areas with associated water scarcity. The main climate impacts have to do with changes in the intensity, freque ncy and location of extreme weather events and, in some cases, water availability rather than temperature change.

ES-7SAP 4.6 Executive Summary

Changes in precipitation patterns will a ffect water supplies nationwide, with precipitation varying across regions and over time. Likely reductions in snowmelt, river flows, and groundwater levels, alon g with increases in saline intrusion into coastal rivers and groundwater will reduce fresh water supplies. All things held constant, population growth will increase the demand for drinking water even as changes in precipitation will change the availab ility of water supplies. Moreover, storms, floods, and other severe weather events are likely to affect infrastructure such as sanitation, transportation, supply lines for food and energy, and communication. Some of the nation’s most expensive infrastructure, such as exposed structures lik e bridges and utility networks, are especially vulne rable. In many cases, water supply networks and stressed reservoir capacity interact w ith growing populations (especially in coastal cities and in the Mountain and Pacific West). The comp lex interactions of land use, population growth and dynamics of settlement pattern s further challenge supplies of water for municipal, industrial, and agri cultural uses. In th e Pacific Northwest th e electricity base dominated by hydropower is directly depende nt upon the water flows from snowmelt. Reduced hydropower would mean the need for supplemental electricity sources, resulting in a wide variety of negative ripple effect s to the economy and to human welfare. Similarly, along the West Coast, communities are likely to experience greater demands on water supplies even as regional precipit ation declines and average snow packs
decrease.

Communities in risk-prone regions, such as coastal zones , have reason to be concerned about potential increase s in severe weather events. The combined effects
of severe storms and sea-level rise in coastal areas or increased risks of fire in more arid areas are examples of how climate change may increase the magnitude of challenges already facing risk-prone regions. Vulnerab ilities may be especially pronounced for rapidly-growing and/or larger metropolitan areas, where the potential magnitude of both impacts and coping requirements are likely to be very large. On the other hand, such regions have greater opportunity to adapt infr astructure and to make decisions that limit vulnerability.

Warming is virtually certain to increase en ergy demand in U.S. ci ties for cooling in buildings while it reduces demands for heating in buildings (see SAP 4.5 Effects of Climate Change on Energy Production and Use in the United States ). De mands for cooling during warm periods could jeopardize th e reliability of service in some regions by exceeding the supply capacity, especia lly during periods of unusually high temperatures. Higher temperatur es also affect costs of living and busin ess operation by increasing costs of climat e control in buildings

Climate change has the potential not only to affect communities directly but also indirectly through impacts on other areas linked to their economies. R egional economies that depend on sectors highly sensitiv e to climate such as agriculture, forestry, water resources, or recreation and tourism could be affected either positively or negatively by climate change. Climate change can add to stress on social and political structures by increasing management and budge t requirements for public services such as public health care, disaster risk reduction, a nd even public safety. As sources of stress grow and combine, the resilience of social a nd political structures are expected to be

ES-8SAP 4.6 Executive Summary

challenged, especially in locales with relatively limited social and political capital.

Finally, population growth and economic de velopment is occurring in those areas that are likely to be vu lnerable to the effects of climate change. Approximately half of the U.S. population, 160 million people, will live in one of 673 coastal counties by 2008. Coastal areas – particularly those on gen tly-sloping coasts and zones with gradual land subsidence – will be at risk for sea level rise, especially related to severe storms and
storm surges.



### ES.4 Climate Change and Human Welfare

The terms human welfare, quality of life, and well-being are often used interchangeably, and by a number of disciplines as diverse as psychology, economics, health science, geograp hy, urban planning, and sociology. There is a shared understanding that all th ree terms refer to aspects of individual and group life that improve living conditions and reduce chances of injury, stress, and loss.

Human well-being is typically defined and measured as a multi-dimensional concept. Taxonomi es of place-specific well-being or quality of life typically converge on six dimensions: 1) economic conditions, 2) natural resources and amenities, 3) human health, 4) public and private infrastructu re, including transportation systems, 5) government and public safety and 6) social and cultural resour ces. Climate change will likely have impacts across all of these dime nsions – both positive and negative. In addition, the positive and negative effects of climate change will affect broader communities, as networks of households, busin esses, physical structures, and institutions are located together across space and time.

Quantifying impacts of climate change on human well-being requires linking effects in quality of life to the projected 1 physical effects of climate change and the consequent effects on human and natural systems. Economic analyses provide a means of quantifying and, in some cases, plac ing dollar values on welfare effects. Even
in cases where welfare effects have been quantified, it is difficult to compare and aggregate a range of effects ac ross a number of sectors.

This report examines four types of effe cts on economic we lfare: those on ecosystems, human health, recreation, a nd amenities associated with climate. Many of the goods and services affected by climate ar e not traded in market s; as a result, they can be difficult to value.” For example, eco logists have already identified a number of ecological impacts of climate change, includi ng the shifting, break up, and loss of certain ecological communities; plant and animal extin ctions and a loss in biodiversity; shifting ranges of plant and animal populations; and ch anges in ecosystem processes, such as

1 A climate projection is the calculated response of the climate system to emissions or concentration

scenarios of greenhouse gases and aerosols , or radiative forcing scenarios , often based on simulations by
climate models . Climate projections are distinguished from climate predictions , in that the former critically depend on the emissions/concentration/ radiative forcing scenario used, and therefore on highly uncertain assumptions of future socio-economic and technological development.

ES-9SAP 4.6 Executive Summary

nutrient cycling and decompos ition. While ecosystems provide a variety of services to humans, including food and fiber, regulating ai r and water quality, s upport services such as photosynthesis, and cultural services such as recreation and aes thetic or spiritual values, these typically are not traded in markets.

Little research has been done linking these ecological changes to changes in services, and still less has been done to quantify, or pla ce dollar values on, these changes. Ecosystem impacts also extend beyond the obvi ous direct effects within the natural
environment to indirect effects on human systems. For instance, nearly 90% of Americans take part in outdoor recreation. The length of season of some of these activities, such as hiking, boating, or golfing, may be favor ably affected by slightly increased temperatures. However, snow and i ce sport seasons are like ly to be shortened, resulting in lost recreation opportunities. The net effect is unclear as decrements associated with snow-based recreation may be more than outweighed by increases in
other outdoor activities.

An agenda for understanding the impacts of climate change on human we lfare may require taking steps both to develop a fr amework for addressing welfare, and to address the data and methodological gaps inherent in the estimation and quantification of effects. To that end, the study of climat e change on human welfare is still developing, and, to our knowledge, no study has made a systematic survey of the full range of welfare impacts associated with cl imate change, much less attempted to quantify
them

.

ES-10SAP 4.6 Executive Summary



### ES.5 Tables

Table ES.1 Examples of Possible Impacts (present to 2050) of Climate Variability and Change on Human Health, Settlements, an d Welfare in the United States and Potential Adaptation Strategies)

Focus Area Climate Event Examples of Possible Impacts Likelihood of Impact Given
Climate Event
Occurs 1 Potential Adaptation Strategies

HUMAN HEALTH

Extreme temperatures

More heat waves and higher maximum
temperatures

Fewer cold waves and higher minimum
temperatures Heat stress/stroke or hyperthermia

Uncertain impacts on mortality 2 Very likely in
Midwest and
northeast urban

centers Early watch and warning syste m s and installation of cooling systems in residential
and commercial buildings,

Changes in precipitation, especially extreme precipitation Contaminated water and food supplies wi th
associated gastrointestinal illnesses, including salmonella and giardia Likely in areas
with out-dated

or oversubscribed water treatment plants Improve
infrastructure to guard against
combined se wer overflow; public health response to
include “boil water”
advisories

Hurricane and storm

surge Injuries from flying debris and drowning / exposure

to contam inated flood
waters and to mold and mildew / exposure to
carbon monoxide poisoning from portable
generators Likely in coastal
zones of the
southeast
Atlantic and the
Gulf Coast Increase knowledge
and awareness of vulnerability to climate change ( e.g., maps showing areas
vulnerable to storm surges); public health
advisories in
immediate aftermath of storm; coordinate
storm relief efforts to insure that people receive necessary
information for safeguarding their
health Temperature-related
effects on ozone 3 Ozone concentrations more likely to increase than decrease; possible
contribution to
cardiovascular and pulmonary illnesses, including exacerbation of
asthma and chronic obstructive pulmonary disorder (COPD) if current regulatory
standards are not
attained Likely in urban
centers in the
mid-Atlantic and
the northeast Public warning vi a air quality action d ays; encourage public transit, walking and bicycling to decrease

emissions

ES-11SAP 4.6 Executive Summary

Focus Area Climate Event Examples of Possible Impacts Likelihood of Potential Adaptation Impact Given Strategies
Climate Event
Occurs 1
Wildfires Degraded air quality, contributing to as thma and COPD aggravated Likely in California, the
Intermountain West, the
southwest and
the southea st Public health air quality advisorie s

HUMAN SETTLEMENTS

Extreme temperatures More heat wave s and higher maximum
temperatures

Fewer cold waves and higher minimum
temperatures Increased net energy demand and expand capacity for pea k cooling

Reduced cold-related
stresses and cos ts Very likely Expand capacity for cooling through public utiliti es; invest in alternative energy

sources

Drought Strain on municipal and agricultural water supplies Very likel y in

intermountain west, desert southwest, and
southeast Reallocat e water among current us ers; develop water
markets to

encourage more efficient allocation; identify new sources through expansion of
reservoirs;

encourage conservation of water for personal and public use; develop drought resistant crops,
Hurricane and storm

surge Disruption of infrastructure, including
levee s ystems, river channels, bridges, and highway systems; disruption of residential neighborhoods Very likely in
southeast
Atlantic Coast
and Gulf Coast Increase kn owledge
and awareness of climate impacts ( e.g., maps showing ar eas vulnerable to storm surges); harden
coastal zones or retreat or relocate; insure against catastrophic loss due to flooding and high
winds
Wildfires Disruption of
communities and property destruction Very likely in

intermountain west, desert southwest, and
southeast Clear vegetation away from buildings;

issue e mergency evacuation orders, prescribed burns, thinning of
combustible matter

ES-12SAP 4.6 Executive Summary

Focus Area Climate Event Examples of Possible Impacts Likelihood of Potential Adaptation Impact Given Strategies
Climate Event
Occurs 1 Late snow fall and early
snow melt Disruption o f water supplies for mun icipal and agricultural use Very likely in

intermountain

west Build reservoirs;

conserve water supplies; divert supply from agricultural to municipal u se; modify operation of existing
infrastructure to account for changes in hydrology; develop drought resistant crops, water prices at replacement cost, enable trading by working with states to develop property rights

HUMAN WELFARE

Extreme temperatures More heat wave s and higher maximum
temperatures

Fewer cold waves and higher minimum
temperatures Discomfort; limit some
outdoor activities /

recreation

Limit some snow- and
cold-related recreational opportunities; substantial

economi c disruption to recreation industry Very likely in
more northern
latitudes of the
United States
and in Alaska

Very likely in

intermountain west, Northern New England and the Upper Great
Lakes Public health watch/warning
advisories

Engage in alternative

recreation activities

Late autumn snow fall and early spring snow melt Limit some snow-related
recreational opportunities; substantial

economic disruption to recreation industry Very likely in

intermountain west, Northern New England and the Upper Great
Lakes Engage in alternative

recreation activities

Extreme precipitation

events L ocal flooding and

contamination o f water supplies Very likely
nationwide Issue flood advisories / warnings

Hurricane and coastal

storms At-risk properties experience flood and wind damage; individuals experience disruption to daily life Very likely in
coastal zone of
the Gulf Coas t and the southern
Atlantic Relocate dwellings and business, and
reinf orce structures and infrastructure to reduce disruptions

1 Based on impacts identified in the published, peer-revie wed literature and expert opinion. Does not include an evaluation of likelihood of the climate event. May include some adaptation ( e.g., in the baseline estimate) but generally does not account for additional changes or developments in adaptive capacity.

2 Many factors contribute to winter mortality, making highly uncertain how climate change could affect mortality. No projections have been published for the United States that incorporates critical factors, such as the influence of
influenza outbreaks.

3 If areas remain in compliance with National Ambient Air Quality Standards, people will not be exposed to unhealthy air ( i.e., cardiovascular and pulmonary illnesses will not occur). More stringent emissions controls may be required to remain in compliance although this is uncertain and additional study is needed.

ES-13SAP 4.6 Executive Summary

Table ES.2 Summary of Regional Vulnerabilities to Climate-Related Impacts 1
Climate-Related Impacts
United States Census Regions Early
Snowmelt Degraded Air Quality Urban Heat
Island Wildfires Heat
Waves Drought Tropical
Storms Extreme
Rainfall
with Flooding Sea Level
Rise

New England

ME VT NH MA RI CT ● ● ● ● ● ● ●

Middle Atlantic
NY PA NJ ● ● ● ● ● ● ● ●

East North Central

WI MI IL IN OH ● ● ● ● ● ●

West North Central

ND MN SD IA NE KS MO ● ● ● ● ●

South Atlantic

WV VA MD MC SC GA FL DC ● ● ● ● ● ● ● ●

East South Central

KY TN MS AL ● ● ● ●

West South Central

TX OK AR LA ● ● ● ● ● ● ● ●

Mountain

MT ID WY NV UT CO AZ NM ● ● ● ● ● ●

Pacific

AK CA WA OR HI ● ● ● ● ● ● ● ● ●

1 Based on impacts identified in the published, peer-reviewed literature and expert opinion.

ES-14

## Synthesis and Assessment Product 4.6

Chapter 1: Introduction

Convening Lead Author: Janet L

. Gamble, U.S. Environmental Protection Agency

Lead Authors: Kristi e L. E bi, ESS, LLC; Anne Grambsch, U.S. Environmental Protection Agency; Frances G. Sussman, Environmental Economics Consulting; Thom as J. Wilbanks, Oak Ridge National Laboratory

Contributing Authors : Colleen E. R eid, ASPH Fellow; Katharine Hayhoe, Texas Tech University; John V. Thomas, U.S. Environmental Protection Agency; Ch ristopher P. Weaver, U.S. Environmental Protection AgencySAP 4.6 Chapter 1: Introduction



### Table of Contents

Table of Contents.............................................................................................................. ............................ 2

1.1 Scope and Approach of the SAP 4.6.......................................................................................... ............ 3

1.2 Climate Change in the United States: Context for an Assessment of Impacts on Human Systems 7

1.2.1 Rising Temperatures...................................................................................................... ................... 8

1.2.2 Trends in Precipitation .................................................................................................. ................... 9

1.2.3 Rising Sea Levels and Erosion of Coastal Zones........................................................................... . 10

1.2.4 Changes in Extreme Co nditions............................................................................................ .......... 11

1.3 Population Trends and Migration Patterns: A Context for Assessing C limate-related Impacts 14

1.3.1 Trends in Total U.S. Population .......................................................................................... ........... 14

1.3.2 Migration Patterns....................................................................................................... ................... 15

1.4. Complex Linkages: The Role of Non-climate Factors...................................................................... 17

1.4.1 Economic Status.............................................................................................................................. 18

1.4.2 Technology............................................................................................................... ....................... 18

1.4.3 Infrastructure........................................................................................................... ....................... 19

1.4.4 Human and Social Capital and Behaviors................................................................................... ... 20

1.4.5 Ins titutio ns ...................................................................................................................................... 20

1.4.6 Interac ting Eff ects...................................................................................................... ..................... 21

1.5 Reporting Uncertainty in SAP 4.6........................................................................................... ............ 22

1.6 References ................................................................................................................ ............................ 24

1.7 Tables.................................................................................................................................................... 36

1.8 Figures .................................................................................................................................................. 37

1 - 2SAP 4.6 Chapter 1: Introduction



### 1.1 Scope and Approach of the SAP 4.6

The Global Change Research Act of 1990 (P ublic Law 101-606) calls for the periodic assessment of the impacts of global environmen tal change for the United States. In 2001, a series of sector and regional assessment s were conducted by the U.S. Global Change Research Program as part of the First Nati onal Assessment of the Potential Consequences of Climate Variability and Change on the Un ited States. Subsequently, the U.S. Climate Change Science Program developed a Strategic Plan (CCSP, 2003) calling for the preparation of 21 synthesis and assessment products (SAPs) to inform policy making and adaptive management across a range of c limate-sensitive issues. Synthesis and
Assessment Product 4.6 examines the effects of global change on human systems. This product addresses Goal 4 of the five strategic goals set forth in the CCSP Strategic Plan to “understand the sensitivity and adaptability of different natural and managed ecosystems and human systems to climate and related global changes” (CCSP, 2003). The “global changes” assessed in this repor t include: climate vari ability and change, evolving patterns of land use within the United States, and changes in the nation’s population.

While the mandate for the preparation of this report calls for evaluating the impacts of global change, the em phasis is on those imp acts associated with climate change. Collectively, global changes are human problems, not simply problems for the natural or the physical world. Hence, this SAP examines the vulnerability of human health and socioeconomic systems to climate change across three foci, including: human health,
human settlements and human welfare. The three topics are funda mentally linked but unique dimensions of global change.

Human health is one of the most basic and di rect measures of huma n welfare. Following past assessments of climate change impact s on human health, SAP 4.6 focuses on human morbidity and mortality associated with extr eme weather, vector-, water- and food-borne diseases, and changes in air quality in the Unite d States. However, it should be noted that climate change in other parts of the worl d could impact human health in the United States. ( e.g., by affecting migration into the U.S., the safety of food imported into the U.S., etc.). Adaptation is a key component to evaluating human health vulnerabilities, including considerati on of public health in terventions (including prevention, response, and treatment strategies) that could be revi sed, supplemented, or implemented to protect human health and how much adaptation could be achieved.

Settlements are where people live. Humans live in a wide variety of settlements in the United States, ranging from small villages and towns with a handful of people to metropolitan regions with millions of inhabita nts. In particular, SAP 4.6 focuses on urban and highly-developed populati on centers in the United States. Because of their high population density, urban areas multiply human health risks, and this is compounded by their relatively high proportions of the very old, the very young, and the poor. In addition, the components of infrastructure that support settlements, such as energy, water supply, transportation, and waste disposal, have vary ing degrees of vulnerability to climate change.

1 - 3SAP 4.6 Chapter 1: Introduction

Welfare is an economic term used to descri be the state of well-being of humans on an
individual or collective basis. Huma n welfar e is an elusive concept, and there is no single, commonly accepted definition or approach to thinking about welfare. There is, however, a shared understanding that increases in human welfare are associated with improvements in individual and communal c onditions in areas such as political power, individual freedoms, economic power, social contacts, health and opportunities for leisure and recreation, along with reductions in injury, stress, and loss. The physical environment, with climate as one aspect, is among many factors th at can affect human welfare via economic, physical, psychological, and social pathways that influence individual perceptions of quality of life. Some core aspects of quality of life are expressed directly in markets ( e.g., income, consumption, pers onal wealth, etc.). The focus in SAP 4.6 is on non-market effects, a lthough, these aspects of human welfare are often difficult to measure and value (Mendelsohn et al. , 1999; EPA, 2000).

The other Synthesis and Assessment Products related to CCSP’s Goal 4 include reports on climate impacts on sea level rise (SAP 4.1), ecosystem changes (SAP 4.2), agricultural production (SAP 4.3), adaptive options for c limate sensitive ecosystems (SAP 4.4), energy use (SAP 4.5) and transportation system impacts along the Gulf Coast (SAP 4.7). Collectively, these reports provide an overview of climate change impacts and adaptations related to a range of hu man conditions in the United States.

The audience for this report includes resear ch scientists, public health practitioners,

resource ma nagers, urban planners, transporta tion planners, elected officials and other policy makers, and concerned citizens. A recen t National Research Council analysis of global change assessments argue s that the best assessments have an audience asking for them, and a broad range of stakeholders (U.S. National Research Council, 2007). This report clearly identifies the pertinent a udience and what decisions it will inform.

Chapters 2-4 describe the impacts of climate change on human systems and outline opportunities for adaptation. SAP 4.6 addresses the questions of how and where clim ate change may impact U.S. socio-economic system s. The challenge for this project is to
derive an assessment of risks associated with health, welf are, and settlements and to develop timely adaptive strategi es to address a range of vulne rabilities. Risk assessments evaluate impacts of climate change across an array of characteri stics, including: the magnitude of risk (both baseline and increm ental risks), the distribution of risks across populations (including minimally-impacted in dividuals as compared to maximallyexposed individuals), and the av ailability, difficulty, irreversib ility, and cost of adaptation strategies. While the state of science limits the ability to conduct formal, quantitative risk assessments, it is possible to develop informati on that is useful for formulating adaptation strategies. Primary goals for adaptation to climate variability and change include:

1. To avoid ma ladaptive responses;
2. To establish protocols to detect and meas ure risks and to ma nage risks proactively when possible;
3. To leverage technical an d institutional capacity;

1 - 4SAP 4.6 Chapter 1: Introduction

4. To reduce current vulnerabilit ies to climate change;
5. To develop adaptive cap acity to addr ess new climate risks that exceed conventional adaptive responses; and,

6. To recognize and respond to impacts wh ich play out across tim e. (Scheraga and Grambsch, 1998; WHO, 2003; IPCC, 2007b)

The issue of co-benefits is cen tral in the consideration of adaptation to climate change. Many potential adaptive stra tegies have co-benefits. Along with helping human populations cope with climate change, adapti ve strategies produce additional benefits. For example:

 Creating and imple menting early warning systems and emergency response plans for heat waves can also improve those services for other emergency responses while improving all-hazards preparedness; (Glantz, 2004)

 Improving the infrastructure and capacity of combined sewer system s to avoid overflows due to changes in precipitation patterns also has th e added benefit of decreasing contaminant flow s that cause beach closings and impact the local ecology; (Rose et al. , 2001)

 A key adaptation technique for settleme nts in coastal zones is to prom ote maintenance or reconstruction of coasta l wetlands ecosystems, which has the added benefit of creation or protec tion of coastal habitats (Rose et al. , 2001); and,

 Promotion of green building practices has added health and welfare benefits as
im proving natural light in office space and schools has been shown to increase productivity and mental health (E dwards and Torcellini, 2002).

Chapter 2 assesses the potential impacts of clim at e change on human health in the United States. Timely knowledge of human health impacts may support our public health infrastructure in devising and implementing st rategies to prevent, compensate, or respond
to these effects. For each of the health endpoints, the a ssessment addresse s a number of topics, including:

 Reviewing evidence of the current burden associated with th e identified health

outcome;

 Characterizing the human health im pact s of current climate variability and projected climate change (to the extent that the current literature allows);

 Discussing adaptation opportunities and support for effective decision ma king; and,

 Outlining ke y knowledge gaps.

Each topic chapter includes research published from 2001 through early 2007 in the United States, or in Canada, Europe, and Au stralia, where results may provide insights for U.S. populations. As such, the health chapte r serves as an update to the Health Sector Assessment conducted as part of the First National Assessment in 2001.

Chapter 3 focuses on the climate change imp acts and adaptations associated with human
settleme nts in the United States. The IPCC Th ird and Fourth Assessment Reports (IPCC,

1 - 5SAP 4.6 Chapter 1: Introduction

2001; IPCC, 2007c) conclude that settlements are among the human systems that are the most sensitive to climate change. For example, if there are changes in climate extremes
there could be serious cons equences for human settlements that are vulnerable to droughts and wildfires, coastal and river floods, sea level rise and storm surge, heat waves, land slides, and windstorms. However, specific changes in these conditions in specific places cannot yet be projected with great confidence. Chapter 3 focuses on the
interactions between settlement characteristic s, climate and other global stressors, with a particular focus on urban areas and other de nsely-developed populat ion centers in the
United States.

The scale and complexity of these built environments, transportation networks, energy
and resource dema nds, and the interdependence of these systems and their populaces, suggests that urban areas are especially vulne rable to multiplying impacts in response to externally imposed environmental stresses. The collective vulnerability of American urban centers may also be determined by the disproportionate share of urban growth in
areas like the Inter-Mountain West or the Gulf Coast. The focus of Chapter 3 is on high density or rapidly-growing settlements and the potential for changes over time in the vulnerabilities associated with place-based ch aracteristics (such as their climate regime, elevation, and proximity to coasts and rivers ) and spatial characteristics (such as whether development patterns are sprawling or compact).

Chapter 4 focuses on the impacts of climate change on human welfare. To examine the impacts of clim ate change on human welfare, this chapter reports on two relevant bodies of literature: approaches to welfare that rely on both qualitative assessment and quantitative measures, and economic approach es that monetize, or place money values, on quantitative impacts.

Finally, Chapter 5 revisits the research r ecommendations and data gaps of previous

assessm ent activities and describes the pr ogress to date and the opportunities going forward. In addition, Chapter 5 reviews the overarching themes derived from Chapters 2-
4.

The remainder of this chapter is designed to provide the reader with an overview of the current state of knowledge regarding:

1. Changes in climate in th e United States;
2. Population trends, mi gration patterns, and the distribution of people across settlements;
3. Non-climate stres sors and their interac tions with climate change to realize complex impacts; and,
4. A discussion of the handling of uncerta inty in reporting s cientific results.

1 - 6SAP 4.6 Chapter 1: Introduction



### 1.2 Climate Change in the United States: Context for an Assessment of Impacts on Human Systems

In the following chapters, the authors examine the impacts on human society of global change, especially those associated with climate change. The impact assessments in Chapters 2-4 do not rely on specific emissions or climate change scenarios but, instead, rely on the existing scientific literature w ith respect to our und erstanding of climate change and its impacts on human health, se ttlements and human well-being in the United States. This report does not ma ke quantitative projections of specific impacts in specific locations based on specific proj ections of climate drivers of these impacts. Instead the report adopts a vulnerability perspective.

A vulnerability approach focuses on estimating risks or opportunities associated with possible im pacts of climat e change, rather than on estimating quantitatively the impacts themselves which would require far more de tailed information about future conditions. Vulnerabilities are shaped not only by existing exposures, sensitivities, and adaptive capacities but also by responses to risks

. In addition, climate change is not the only change confronting human societies: from a vulnerability perspective projected changes in populations, the economy, technology, inst itutions, infrastructure, and human and social capital are among the factors that also affect vulnerability to climate change. The report reviews historical trends and variability to point to vulnerabilities and then, where possible, determines the likely direction and range of potential climate-related impacts.

In the United States, we are observing the evidence of long-term ch anges in temp erature and precipitation consistent with global warming. Changes in average conditions are being realized through rising temperatures, ch anges in annual and seasonal precipitation, and rising sea levels. Observations also indi cate there are changes in extreme conditions, such as an increased frequency of heavy rain fall (with some increase in flooding), more heat waves, fewer very cold days, and an increase in areas affected by drought. Frequencies of tropical storms and hurricanes vary considerab ly from year to year and there are limitations in the quali ty of the data which make it difficult to discern trends, but evidence suggests some increases in their intensity and duration since the 1970s (Christensen et al. , 2007).

The following sections provide a brief introducti on to climate change as a context for the following chapters on impacts and adaptation. SAP4.6 did not itself evaluate climate change projections as they were not used quantitatively in this assessment. The Intergovernmental Panel on Climate Change provides a comprehensive evaluation of climate change science. In their Summary for Policy Makers (IPCC, 2007a) reports the following observed changes in global climate:

 “Warming of the climate system is unequivocal, as is now evident from
observations of increases in global average air and ocean temperature, widespread melting of snow and ice, and ri sing global average sea level.”

 “Eleven of the last twelve years ra nk among the 12 warm est years in the instrumental record of global su rface temperatures (since 1850).”

1 - 7SAP 4.6 Chapter 1: Introduction

 “Average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes s ea water to expand, contributing to sea
level rise.”

 “Mountain glaciers and snow cover ha ve declined on average in both
hemi spheres.”

 “The frequency of heavy precipitation ev ents has increased over mo st land areas, consistent with warming and observed in creases of atmospheric water vapor.”

 “Widespread changes in extreme temperatur es have been observed over the last 50 years... Hot days, hot nights, and heat waves have become m ore frequent.”

 “There is observational evidence for an increase of intense tropical cyclo ne activity in the North Atlantic since about 1970.” (IPCC, 2007a)

Note that these changes are fo r the entire globe: changes in the United States may be similar or differ from these global changes. The following sections examine U.S. climate
trends and historical records related to te mperature, precipitation, sea level rise, and changes in hurricanes and other catastrophic ev ents. Information is also drawn from the North American Chapter of the IPCC Fourth Assessment Report and the Climate Change Science Programs Synthesis and Assessment Product 3.3: Weather and Climate Extremes in a Changing Climate. Taken together, this discussion provides a context from which to assess impacts of climate change on hu man health, human welfare, and human
settlements.

1.2.1 Rising Temperatures
Climate change is already affecting the Un ited States. Accord ing to long-term stationbased observational records such as the Historical Climatology Network (Karl et al.

, 1990; Easterling et al. , 1999; Williams et al. , 2007), temperatures across the continental United States have been rising at a rate of 0.1°F per decade since the early 1900s. Increases in average annual temperatures over the last century now exceed 1°F (Figure 1.1a). The degree of warming has varied by region across the United States, with the West and Alaska experiencing the greatest degree of warming (U.S. Environmental Protection Agency, 2007). These changes in temp erature have led to an increase in the number of frost-free days, with the great est increases occurring in the West and Southwest (Tebaldi et al. , 2006). The Intergovernmental Panel on Climate Change, in its most recent assessment report concluded th at “Warming of the climate system is unequivocal...” (IPCC, 2007a).

Figure 1.1 Observed trends in annual average (a) temperature ( o F) and (b) precipitation (inches) across the continental United St ates from 1896 to 2006 (Source: NCDC, 2007)

The current generation of global climate models , run with IPCC SRES scenarios of future greenhouse gas em issions, simulate future change s in the earth’s climate system that are greater in magnitude and scope than those already observed. According to the IPCC, by
the end of the 21 st century, annual surface temperature increases are projected to range
from 2-3°C near the coasts in the conter minous United States to more than 5°C in northern Alaska. Nationally, annual warming in the United States is projected to exceed
2 o C, with projected increases in summerti me temperatures ranging between 3 and 5°C

1 - 8SAP 4.6 Chapter 1: Introduction

(greatest in the Southwest). The largest warming is projected to reach 10 o C for winter temperatures in the northernmost parts of Alaska. (IPCC, 2007c). For additional information about the modeling results, se e the IPCC Fourth Assessment Working Group I Report, especially Chapter 11: Regi onal Climate Projections (Christensen et al. , 2007)

1.2.2 Trends in Precipitation
Shifting precipitation patterns have also b een observed. Over the last century, annual precipita tion across the continental United Stat es has been increasing by an average of 0.18 inches per decade (Figure 1.1b). Broke n down by season, winter precipitation around the coastal areas, incl uding the West, Gulf, and Atlantic coasts, has been increasing by up to 30% while precipitation in the central part of the country (the Midwest and the Great Plains) has been d ecreasing by up to 20%. Large-scale spatial patterns in summer precipitati on trends are more difficult to identify, as much of summer
rainfall comes in the form of small-scale convective precipitation. However, it appears
that there have been increases of 20-80% in summer rainfall over California and the Pacific Northwest, and decreases on the order of 20-40% across much of the south. The IPCC reports that rainfall is arriving in more inte nse events. (IPCC, 2007a).

El Niño events (a periodic warming of the tropical Pacific Ocean between South America and the International Date Line) are associat ed with increased precip itation and severe storms in some regions, such as the southeast United States and the Great Basin region of
the western United States. El Niño events have also been characterized by warmer temperatures and decreased precipitation in other areas, such as western Canada, the Pacific Northwest and parts of Alaska

. Historically, El Niño even ts occur about every 3 to 7 years and alternate with the opposite phases of below- average temperatures in the eastern tropical Pacific (La Niña). Since 1976-1977, there has been a tendency toward more prolonged and stronger El Niños (IP CC, 2007a). However, recent analyses of
climate simulations indicate no consistent trends in future El Niño amplitude or frequency (Meehl et al. , 2007)

Global model simulations summarized in the North American Chapter of the IPCC AR4, show moderate increases in pr ecipitation (10% or less) over much of the United States over the next 100 years, except for the southwes t. However, projecte d increases in these simulations are partially offset by increases in evaporation, resulting in greater drying in the central part of the United States. Projec tions for the central, eastern and western regions of the United States show similar seasonal characteristics ( i.e., winter increases, summer decreases), although there is greater consensus for winter increases in the north and summer decreases in the south. However, uncertainty around the projected changes is large (IPCC, 2007b).

1.2.2.1 Changes in Snow Melt and Glacial Retreat
Warmer temperatures are melting mountain glaciers and more winter precipitation in northern states is falling as ra in instead of snow. (Huntington et al. , 2004). Snow pack is also melting faster, affecting stream flow in rivers. Over the last fifty years, changes in the timing of snow melt has shifted the schedul e of snow-fed stream flow in the western part of the country by 1-4 weeks earlier in the year (Stewart et al. , 2005). The seasonal

1 - 9SAP 4.6 Chapter 1: Introduction

“center of stream flow volume” ( i.e., the date at which half of the expected winter-spring stream flow has occurred) also appears to be advancing by on average one day per decade for streams in the Northeast (Huntington et al. , 2003).

This trend is projected to continue, with more precipitation falling as rain rather than snow, and snow season length and snow depth ar e generally projected to decrease in most of the country. Such changes tend to favor in creased risk of wint er flooding and lowe r summer soil moisture and streamflows (IPCC, 2007a).

1.2.3 Rising Sea Levels and Erosion of Coastal Zones
Sea levels are rising and the IPCC concluded with high confidence that the rate of sea
level rise increased from the 19th to the 20 th centuries (IPCC, 2007a). The causes for observed sea-level rise over the past century include thermal expansion of seawater as it warms and changes in land ice ( e.g., melting of glaciers and snow caps). Over the 20 th
century, sea level was rising at a rate of about 0.7 inches per decade (1.7 mm/yr ± 0.5 mm). For the period 1993 to 2003, the rate was nearly twice as fast, at 1.2 inches per decade (3.1 mm/yr ± 0.7 mm). However, there is consid erably decadal variability in the tide gauge record so that it is unknown whet her the higher rate in 1993 to 2003 is due to decadal variability or an increase in the longer-term trend. (Bindoff et al ., 2007). In the past century, global sea level rose 5-8 inches.

Spatially sea-level change varies considerably: in some regions, rates are up to several times the global m ean rise, while in other regions sea level is falling. For example, for the mid-Atlantic coast ( i.e., from New York to North Carolina), the “effective” or relative sea-level rise rates have exceeded the global rate due to a combination of land subsidence and global sea level rise. In th is region, relative sea-level rise rates ranged between 3 to 4 mm per year (~1ft per century) over the 20th cen tury. In other cases, local sea-level rise is less than the global aver age because the land is still rising (rebounding) from when ice sheets covered the area, depressing the Earth’ s crust. Local sea le vels can actually be falling in some cases (for example, the Pacific Northwest coast) if the land is rising more than the sea is falling (f or additional details about sea le vel rise and its effects on US coasts please see Synthesis and Assessment Product 4.1 Coastal elevations and sensitivity to sea level rise)

.

Rising global temperatures are projected to accel erate the rate of sea-level rise by further expanding o cean water, melting mountain glaci ers, and increasing the rate at which
Greenland and Antarctic ice sheets melt or di scharge ice into the ocean s. Estimates of sea-level rise for a global temperature incr ease between 1.1 and 6.4°C (the IPCC estimate of likely temperature increases by 2100) ar e about 7 to 23 inches (0.18m to 0.59m), excluding the contribution from accelerated ice discharges from the Greenland and Antarctica ice sheets. Extrapol ating the recent acceleration of ice discharges from the polar ice sheets would imply an additional co ntribution up to 8 inches (20cm). If melting of these ice caps increases, larger values of sea-level rise cannot be excluded (IPCC, 2007a).

1 - 10SAP 4.6 Chapter 1: Introduction

1.2.4 Changes in Extreme Conditions
The climatic changes described above are often referred to as changes in “averag e” conditions. Most observations of temperature w ill tend to be close to the average: days with very hot temperatures happen infrequentl y. Similarly, only rarely will there be days with extremely heavy precipitation. Climate cha nge could result in a shift of the entire distribution of a meteorological variable so that a relatively small shift in the mean could be accompanied by a relatively large change in the number of relatively rare (according to today’s perspective) events. For example, with an increase in average temperatures, it would be expected there would be an increa se in the number of very hot days and a decrease in the number of very cold days. Other, relatively rare, extreme events of concern for human health, welfare and sett lements include hurricanes, floods and droughts.

In general, it is difficult to attribute any i ndividual extrem e event to a changing climate. Because extreme events occur infrequently, there is typically limited information to
characterize these events and their trends. In addition, extreme events usually require
several conditions to exist for the event to occur, so that linking a particular extreme event to a single, specific cause is problematic. For some extreme events, such as extremely hot/cold days or rainfall extremes, there is more of an observational basis for analyzing trends, increasing our understanding and ability to project future changes.

Finally, there are many different aspects to ex tremes. Freque ncy is perhaps the most often discussed but changes in other aspect s of extremes such as intensity ( e.g., warmer hot days), time of occurrence (e.g., earlier snowmelt), duration (e.g., longer droughts), spatial extent and location are also important when determining impacts on human systems.

Synthesis and Assessment Product 3.3 Weather and Climate Extremes in a Changing
Climate (CCSP, 2008) has a m uch more detailed discussion of climate extremes that are only very briefly described here. The interest ed reader is referred to that report for
additional details.

1.2.4.1 Heat and Cold Waves
Extreme temperatures ( e.g., tem peratures in the upper 90 th or 95 th percentile of the distribution) often change in parallel with average temperatures . Since 1950, there are more 3-day warm spells (exceeding the 90 th percentile) when averaged over all of North America (Peterson et al. , 2008). While the number of heat waves has increased, the heat
waves of the 1930s remain the most severe in the U.S. historical record. Mirroring this shift toward more hot days is a decrease in unusually cold days during the last few decades. There has been a corresponding decrease in frost days and a lengthening of the frost-free season over the past century. The number of frost days decreased by four days per year in the United States during the 1948- 1999 period, with the largest decreases, as many as 13 days per year, occurring in the western United States (Easterling, 2002). For the United States, the average length of the frost-free season over the 20 th century increased by almost two weeks (Kunkel et al. , 2004).

1 - 11SAP 4.6 Chapter 1: Introduction

Recent studies have found that there is an increased likelihood of more intense, longerlasting and more frequent heat wa ves (Meehl and Tebaldi, 2004, Schar et al. , 2004, Clark
et al. , 2006). As the climate warms, the number of frost days is expected to decrease (Cubasch et al. , 2001) particularly along the northwest coast of North America (Meehl et al. , 2004). SAP 4.6, using a range of greenhous e gas emission scenarios and model simulations, found that hot days, hot nights a nd heat waves are very likely to become more frequent, that cold days and cold ni ghts are very likely to become much less frequent, and that the number of days with fr ost is very likely to decrease (CCSP, 2008). Growing season length is related to frost days, which is projected to increase in a warmer climate in most areas (Tebaldi et al. , 2006).

1.2.4.2 Heavy Precipitation Events

Over the 20 th century, periods of heavy downpours became more frequent and more intense and accounted for a larg er percentage of total prec ipitation (Karl and Knight, 1997; Groisman et al. , 1999, 2001, 2004, 2005; Kunkel et al. , 1999; Easterling et al.

, 2000; Kunkel, 2003). These heavy rainfall even ts have increased in frequency by as
much as 100% across much of the Midwest and Northeast over the last century (Kunkel
et al. , 1999). These findings are consistent w ith observed warming and associated increases in atmospheric water vapor.

The intensity of precipitation even ts is projected to increase, particularly in high latitude areas that experien ce increases in mean precipitation (Meehl et al. , 2007). In areas where mean precipitation decreases (most subtropical and mid-latitude re gions), precipitation intensity is projected to increase but ther e would be longer peri ods between rainfall events. Precipitation extremes increase more than does the mean in most tropical and mid- and high-latitude areas. Some studies project widespread increases in extreme precipitation (Christensen et al. , 2007), with greater risks of not only flooding from intense precipitation, but also droughts from greater temporal variability in precipitation. SAP 3.3 concluded that, over most regions, fu ture precipitation is likely to be less frequent but more intense, and precipitation extremes are very likely to increase (CCSP, 2008).

1.2.4.3 Changes in Flooding
Heavy rainfall clearly can lead to floodi ng, but assessing whether observed changes in precipitation have lead to simila r trends in flooding is difficult for a num ber of reasons. In particular, there are many human influences on streamflow ( e.g., dams, land-use changes, etc.) that confound climatic in fluences. In some cases, researchers using the same data came to opposite assessments about trends in high streamflows (Lins and Slack, 1999, 2005; Groisman et al. , 2001, 2004). Short duration extreme precipitation events can lead to localized flash flooding, but for large river basins, significant flooding will not occur from these types of episodes alone; excessive precipitation mu st be sustained for weeks to months for flooding to occur.

1.2.4.4 Changes in Droughts
An extended period with little precipitation is the ma in cause of drought, but the intensity of a drought can be exacerbated by high temper atures and winds, a lack of cloudiness/low

1 - 12SAP 4.6 Chapter 1: Introduction

humidity which result in high evaporation ra tes. Droughts occur on a range of geographic scales and can vary in their duration, in some cases las ting years. The 1930s and the 1950s experienced the most widespread and severe drought conditions (Andreadis et al.

, 2005), although the early 2000s also saw severe droughts in some areas, especially in the western United States (Piechota et al., 2004).

Based on observations averaged over the United States, there is no clear o verall national trend in droughts (CCSP, 2008). Over the past century, the area affe cted by severe and extreme drought in the United States each ye ar averaged about 14%: by comparison, in 1934 the area affected by drought was as high as 65% (CCSP, 2008). In recent years, the drought-affected area ranged between 35 and 40% (CCSP, 2008). These trends at the national level however mask important diffe rences in drought conditions at regional scales: one area may be very dry while another is wet. For example, in the Southwest and parts of the interior of the West increased temperatures ha ve led to rising drought trends (Groisman et al. , 2004; Andreadis and Lettenmaier, 2006) . In the Southwest, the 1950s were the driest period, though droughts in th e past 10 years are approaching the 1950s drought (CCSP, 2008). There are also recent regional tendencies toward more severe droughts in parts of Al aska (CCSP, 2008).

Several generations of global climate models , including the most recent find an increase
in summ er drying in the mid latitudes in a future, warmer climate (Meehl et al. , 2007). This tendency for drying of the mid-continen tal areas during summe r indicates a greater risk of droughts in those regions (CCSP, 2008). Analyses using several coupled global circulation models project an increased frequency of drought s lasting a month or longer in the Northeast (Hayhoe et al. , 2007) and greatly reduced an nual water availability over the Southwest (Milly et al. , 2005). SAP 3.3 concluded that dr oughts are likely to become more frequent and severe in some regions of the country as higher air temperatures increase the potential for evaporation.

1.2.4.5 Changes in Hurricanes
Assessing changes in hurricanes is difficult: Th ere have been large f luctuations in the number of hurricanes from year to year a nd from decade to decade. Furthermore, it is only since the 1960s that reliable data can be assembled for assessing trends. In general, there is increasing uncertainty in the data r ecord the further back in time one goes but significant increases in tropical cyclone fr equency are likely si nce 1900 (CCSP, 2008). However, the existing data and an adjusted record of tropical storms indicate no significant linear trends be ginning from the mid- to late 1800s to 2005 (CCSP, 2008). Moreover, SAP 3.3 concluded that there is no evidence for a long-term increase in North
American mainland land -falling hurricanes.

Evidence suggests that the intensity of A tlantic hurricanes and tropical storms has
increased ov er the past few decades. SAP3.3 i ndicates that there is evidence for a human contribution to increased sea surface temperatures in the tropical Atlantic and there is a strong correlation to Atlantic tropical storm frequency, durat ion, and intensity. However, a confident assessment will require further stud ies. An increase in extreme wave heights

1 - 13SAP 4.6 Chapter 1: Introduction

in the Atlantic since the 1970s has been observed: consiste nt with more frequent and intense hurricanes (CCSP, 2008).

For North Atlantic hurricanes, SAP3.3 concludes that it is likely that wind speeds and
core rainf all rates will increase (Henderson-Sellers et al. , 1998; Knutson and Tuleya, 2004, 2008; Emanuel, 2005). However, SAP3.3 c oncluded that “frequency changes are currently too uncertain for c onfident projection” (CCSP, 2008). SAP3.3 also found that the spatial distribution of hurricanes will likely change. Storm surge is likely to increase due to projected sea level rise, though the de gree to which these will increase has not been adequately studied (CCSP, 2008).



### 1.3 Population Trends and Mi gration Patterns: A Context for Assessing Climate-related Impacts

Assessments of climate-related risk must acc ount for the size of the population, including especially sensitive sub-populations, and their geographic distribution across the landscape. The following discussion provides a basis for assessing the interactions of global change within the larger context of demographic trends . In particular, the socialcharacteristics of a populace may interact with its spatial distribution to produce a nonlinear risk. In such instances, risk assessm ents are shaped by questions such as:

 Which counties, sta tes, and regions will grow most rapidly?

 How many people will live in at-risk area s, such as coastal zones, flood plains,
and arid areas?

 What share of retirees will migra te and where will they move?

1.3.1 Trends in Total U.S. Population
The US population numbered some 280 m illion individuals in 2000. 1 In 1900, the US population numbered about 76 million people; fifty years later the population had roughly doubled to 151 million people.

Population projections are estimates of the popul ation at future dates. They are based on assumptions about future births, deaths, in ternational m igration, and domestic migration and represent plausible scen arios of future population.

In 2000 the IPCC published a set of emission sc enarios for use in the Third Assessme nt Report (Nakicenovic et al ., 2000). The SRES scenarios were constructed to explore future developments in the global environment with special reference to the production of greenhouse gases and aerosol precursor emissions . The SRES team defined four narrative storylines labeled A1, A2, B1 and B2, descri bing the relationships between the forces driving greenhouse gas and aeros ol emissions and their evol ution during the 21st century for large world regions and globally. Each st oryline represents different demographic, social, economic, technological, and envi ronmental developments that diverge in increasingly irreversib le ways. (Nakicenovic et al ., 2000)

1 Information on historical US population data and current population estimates and projections can be
found at http://www.census.gov/

.

1 - 14SAP 4.6 Chapter 1: Introduction

The US Census Bureau periodically releases projections for the resident population of the
United States based on Census da ta. The cohort-component methodology 2 is used in these projections. Alternative assumptions of fertility, life expectancy, and net immigration yield low, middle and high projections.

Figure 1.2 displays the SRES a nd Census population projections 3 for the US. The Census projections span a greater range than th e SRES scenarios: by 2100 the low series projection of 282 million is below the curren t population while the high projection is about 1.2 billion, or about four times the cu rrent population. The Census middle series projection is relatively close to the SRES A2 scenario (570 million vs. 628 million in 2100), while the SRES A1/B1 and B2 scenarios fall below the Census middle projection.

Figure 1.2 US Population Projections 2000-2100

1.3.1.1 Aging of the Population
The US population has not simply increased by 300% over the past century, it has also shifted in its demographic structure. For exam ple, in 1900 less than 4% of the US population was 65 years or older; currently ab out 12% of Americans are 65 or older (He
et al. , 2005). By 2050, the US population aged 65 a nd older is projecte d to be about 86 million, or about 21% of the total population. Nearly 5% of the projected population in 2050, over 20 million people, will be 85 years or older (He et al. , 2005). Figure 1.3 displays the projected age di stribution for the total reside nt population of the United States by sex for the middle projection series.

Figure 1.3 Population Pyramids of the US 2000 and 2050 (Interim Projections based on 2000 Census)

The projected increase in the elderly population is an important variable in projections of the effects of climate change. The elderly ar e identified in many health assessments as more vulnerable than younger age groups to a range of health outcomes associated with climate change, including injury resulting from weather extremes such as heatwaves, storms and floods (WHO, 2003; IPCC, 2007b; NAS T, 2001). Aging also can be expected to be accompanied by multiple, chronic i llnesses that may result in increased vulnerability to infectious disease (NAST, 2001). Chapter two in this report also identifies the elderly as a vulnerable subpopulation.

1.3.2 Migration Patterns
Although numbers produced by population proj ections are important, the striking
rela tionship between potential future sett lement patterns and the areas that may experience significant impacts of climate change is the critical insi ght. In particular, nearly all trends point to more American s living in areas that may be especially vulnerable to the effects of climate change (see Figure 1.4). For example, many rapidly

2 See Census web-site for additional details on the projection methodology.

3 The Census projections are based on the 1990 Census. Preliminary projections based on the 2000 Census
for 2000-2050 are available.

1 - 15SAP 4.6 Chapter 1: Introduction

growing places in the Mountain West may al so experience decreased snow pack during winter and earlier spring melting, leading to lo wer stream flows, particularly during the high-demand period of summer.

The continued growth of arid states in the We st is therefore a critical crossroads for human settlements and climate change. These st ates are expected to account for one-third of all U.S. population growth over the ne xt 25 years (US Census Bureau, 2005). The combined effects of growing demand for wa ter due to a growing population and changes in water supplies associated with climatic change pose important challenges for these states. For example, a study commissi oned by the California Energy Commission
estimated that the Sierra Mountain snow pack could be reduced by 12% to 47% by 2050 (Cayan et al. , 2006). At the same time, state proj ections anticipate an additional 20 million Californians by that date (California Department of Finance, 2007).

Figure 1.4: U.S. Population and Growth Trends wi th evidence of more pronounced growth projected along the coasts, in urban ce nters, and in cities in the South and West (NAST, 2001)

Growth in coastal population has kept pace wi th population growth in other parts of the country, bu t given the small la nd area of the coasts, the de nsity of coastal communities has been increasing (Crossett et al., 2004). Over 50% of the US population now lives in the coastal zone, and coastal areas are projected to conti nue to increase in population, with associated increases in population de nsity, over the next several decades. The overlay of this migration pattern with climate change projections has several implications. Perhaps the most obvious is the increased exposure of people and property
to the effects of sea leve l rise and hurricanes (Kunkel et al., 1999). With rapidly growing communities near coastlines, property damage s would be expected to increase even without any changes in storm fr equency or intensity (Changnon et al., 2003).

1.3.2.1 How Climate Impacts Migration Patterns

It is often said that Americans are a nation of movers and data collected for both the 1990 and 2000 Census support this notion. While rough ly half of the U.S. population had lived
in the sam e house for the previous five years, nearly 10% had recently moved from out of

state. 4 In other words, during the five year period preceding each Census, over 20
million Americans had moved across state lines and half of those moved to different regions.

Although many forces shape domestic migration, climate is a key elem ent of perceived quality of life. In turn, quality of life can be an important factor driving the relocation
decisions of households and businesses. Th e popularity of the Places Rated Almanac and other publications ranking citi es’ livability illustrates the concept’s importance. Additionally, many of the indicators in thes e reports are based directly on climatic conditions (average winter and summer temp erature, precipitation, days of sunshine, humidity, etc.).

4 http://www.census.gov/Press-Re lease/www/2002/sumfile3.html

1 - 16SAP 4.6 Chapter 1: Introduction

A range of studies have attempted to quantify how natural amenities, including a favorable climate, affect migration. While the methods vary 5 the conclusions are similar. In general:

 People move for a variety of reasons othe r than clim ate, such as: proximity to family and friends, employment opportunities, lower cost of living, and aesthetics,

 Areas with natura l amenities that are clos e to urban centers have attracted the largest numbers of in-migrants (Serow, 2001);

 Climate’s impact on migration varies by in com e with lower income groups also moving to colder areas in which their wage s are likely to compare more favorably to the cost of living (Rebhun and Raveh, 2006);

 For retirees, weather is a far more importa nt rationale cited fo r moving out of an area than moving to an area (AARP, 2006); and,

 Population growth in rural counties is str ongly related to a more favorable climate
and other k ey natural amenities (McGranahan, 1999). In addition, new information technologies may make it possi ble for some urban dwellers to move to and work from rural regions.



### 1.4. Complex Linkages: The Ro le of Non-climate Factors

Climate is only one of a number of global changes that affect human well-being. These non-climate processes and stresses interact with climate change, determining the overall severity of climate impacts. Moreover, climate change impacts can spread from directly impacted areas and sectors to other areas and sectors through ex tensive and complex linkages (IPCC, 2007b). Evaluating future clim ate change impacts therefore require assumptions, explicit and implicit, about how future socioeconomic conditions will develop. The IPCC (1994) recommends the use of socioeconomic scenarios in impacts assessments to capture in a consistent way these factors.

Socioeconomic scenarios have tended to focus on variables such as population and
measures of econom ic activity ( e.g., Gross Domestic Product) that can be quantified using well-established models or methods (for examples of economic models which have been used for long run projections, see Nakicenovic et al. , 2000; NAST 2001; Yohe et al. , 2007). While useful as a starting point, some key socioeconomic factors may not allow this type of quantif ication: they could however be incorporated through a qualitative, “storyline” approach and thus yield a more fully developed socioeconomic scenario. The UNEP country study program guidan ce (Tol, 1998) notes the role of formal modeling in filling in (but not defining) soci oeconomic scenarios but also emphasizes the role of expert judgment in blending dispar ate elements into c oherent and plausible scenarios. Generally socioeconomic scenarios have been developed in situations where it is not possible to assign levels of probability to any particular futu re state of the world and therefore it usually is not appropriate to ma ke confidence statemen ts with respect to a specific socioeconomic scenario (Moss and Schneider, 2000).

5 Study methodologies include: aggregate studies of population changes alongside regional characteristics, explanatory models developed from individual migration data and individual surveys.

1 - 17SAP 4.6 Chapter 1: Introduction

Socioeconomic scenarios incl ude non-environmental factors that influence exposures, vulnerability and impacts. Factors that may be incorporated into a scenario include:

 Population ( e.g., dem ographics, immigration, do mestic migration patterns);

 Economic status (income, prices);

 Technology ( e.g., pesticides, vaccines, transportation m odes, wireless communications);

 Infrastructure ( e.g. , water treatment plants, sewers, and drinking water systems; public health system s; roads, rails and bridges; flood c ontrol structures);

 Human capital and social context and behaviors ( e.g., skills and knowledge, social networks, lifestyles, diet); and,

 Institutions (legislative, social, ma nagerial).

These factors are important both for characteri zing potential effects of a changing clim ate on human health, settlements and welfare and fo r evaluating the ability of the US to adapt to climate change.

1.4.1 Economic Status
The US is a developed economy with GDP approaching $14 trillion and per capita
income of $38,611 in 2007 (US BEA, 2008). The US economy has large private and public sectors, with strong emphasis on ma rket mechanisms and private ownership (Christensen et al. , 2007). A nation’s economic stat us clearly is important for determining vulnerability to climate cha nge: wealthy nations have the economic resources to invest in adaptive measures and bear the costs of impacts and adaptation thereby reducing their vulner ability (WHO, 2003; IPCC, 2001) . With the aging of the population (described in Secti on 1.3.1.1) however, the costs of health care are likely to rise over the coming decades (Christensen et al. , 2007). Moreover, if the trend toward globalization continues through the 21 st century, markets, primary factors of production, ownership of assets, and policies and govern ance will become more international in outlook (Stiglitz, 2002). Unfortunately, there ha s been little resear ch to understand how
these economic trends interact with clim ate change to affect vulnerability ( i.e., whether they facilitate or hinder adaptation to climate change in the US).

1.4.2 Technology
The past half-century has seen stunning le vels of technological advancement in the
United States which has done m uch to im prove American standards of living. The availability and access to technology at vary ing levels, in key sectors such as energy, agriculture, water, transpor tation and health is a ke y component to understanding vulnerability to climate change. Many technol ogical changes, both la rge and small, have reduced American’s vulnerability to clim ate change (NAST, 2001). Improved roads and automobiles, better weather and climate for ecasting systems, computers and wireless communication, new drugs and vaccines, better building materials, more efficient energy production – the list is very long indeed– have contributed to America’s material well being while reducing vulnerabil ity to climate. Many of the adaptive strategies that are currently deployed that protect human beings from climate involve technology (e.g., warning systems, air conditioning and heating, pollution controls, building design, storm

1 - 18SAP 4.6 Chapter 1: Introduction

shelters, vector control, water treatm ent and sanitation) (WHO, 2003). Continued advances in technology in the 21 st century can increase substan tially our ability to cope with climate change (IPCC, 2007a; USGCRP, 2001).

However, it will be important to assess risk s from proposed technological adaptations to avoid or mitigate advers e effects (i.e., maladaptation) (Patz, 1996; Klein and Tol, 1997). For example, if new pesticides are used to control disease vectors their effects on human populations, insect predators, a nd insect resistance to pestic ides need to be considered (Scheraga and Grambsch, 1998; Gubler et al. , 2001).

In addition, technological change can interact in complex wa ys with other socioeconomi c factors (e.g., migration patterns) and affect vulnerabi lity to climate change. For example, advances in transportation t echnology – electric streetca rs, freight trucks, personal automobiles, and the interstate highway syst em – have fueled the decentralization of urban regions (Hanson and Giuliano 2004; Ga rreau 1991; Lang 2003). More recently, the rapid development of new information technol ogies, such as the internet, have made previously remote locations more accessible for work, recreation, or retirement. Whether these developments increase or decrease vul nerability is unknown, but they do indicate
the need for socioeconomic scenarios to bett er characterize the complex linkages between
climate and non-climate factors in order evaluate vulnerability.

1.4.3 Infrastructure

Communities have reduced, and can further reduc e, their vulnerability to a dverse climate effects through investments in infrastructure. For example, water resources in the US have been modified and intensively managed ov er the years, partly in response to climate variability (Cohan and Miller, 2001). These investments range from small, privately constructed impoundments, water diversions an d levees to major projects constructed by federal and state governments. Public health in frastructures, such as sanitation facilities, waste water treatment, and laboratory build ings reduce climate change health risks (Grambsch and Menne, 2003). Coastal communitie s have developed an array of systems to manage erosion and protect against floodi ng (see SAP 4.1 for an extensive discussion). More generally infrastructure such as roads, rails and bridges, water supply systems and drainage, mass transit and buildings can reduce vulnerability (Grambsch and Menne, 2003).

However, infrastructure can increase vulnerabi lity if its presence encourages people to
locate in mo re vulnerable areas. For example, increasing the density of people in coastal metropolitan areas, dependent on extensive fixed infrastructure, can increase vulnerability to extreme events such as floods, storm surges and heat waves (NAST, 2001). In assessments of severe storms, meas ures of property damage are consistently higher and loss of life lower in the US when compared with less- developed countries (Cohan and Miller, 2001), reflecting both the hi gh level of development in coastal zones and the effectiveness of warnings and emerge ncy preparedness (Pielke and Pielke, 1997).

Fixed infrastructure itself has the potential to be adversely impacted by climate change,
which can in crease vulnerability to clim ate change. For example, flooding can

1 - 19SAP 4.6 Chapter 1: Introduction

overwhelm sanitation infrastructure and lead to water-related illnesses (Grambsch and Menne, 2003). Much of the transportation infr astructure in the Gulf Coast has been
constructed on land at elevations below 16.4 f t: storm surge, therefore poses risks of immediate flooding of infrastructure and da mage caused by the for ce of floodwaters (see SAP 4.7 for additional information on the vulnerability of Gulf Coast transportation infrastructure to climate change). Damage to transportation infrastructure can make it
more difficult to assist affected populations (Grambsch and Menne, 2003).

1.4.4 Human and Social Capital and Behaviors
While these factors are extremely difficult to quantify, much less project into the future, they are widely perceived to be important in determ ining vulnerability in a number of different ways. In general, countries with higher levels of “human capital” or knowledge are considered to be less vulnerable to climate change. Effective adaptation will require
individuals skilled at rec ognizing, reporting and responding to climate change effects. Moreover, a number of the adaptive measur es described in the literature require knowledgeable, trained and skilled personnel to implement them. For example, skilled public health managers, who understand survei llance and diagnostic information, will be needed to mobilize appropriate responses. People trained in the operation, quality control
and maintenance of laboratori es, communications equipment, and sanitation, wastewater, and water supply systems are also key (G rambsch and Menne, 2003). Researchers and scientists spanning a broad range of disciplin es will be needed to provide a sound basis for adaptive responses.

In addition to a countries’ human capital ( i.e., the knowledge, experien ce and expertise of its citizens) the relationships, exchange of resources and knowledge, and the levels of
trust and conflicts be tween individuals ( i.e., “social capital”) are also important for understanding future vulnerability to c limate change (Adger, 2003; Lehtonen, 2004; Pelling and High, 2005). Social networks can play an important role in coping and recovery from extreme weathe r events (Adger, 2003). For exam ple, individuals who were socially isolated were found to be a greater risk of dyi ng from extreme heat (Semenza et al. , 1996), as well as people living in neighborh oods without public gathering places and
active street life (Klinenberg, 2002).

Individual behaviors and responses to cha nging conditions also determine vulnerability. For example, fitness, body composition, and le vel of activity are am ong the factors that determine the impact extremely hot weathe r will have on the human body (see Chapter 2 for additional information). Whether this trend continues or not could have important implications for determining vulnerability to climate cha nge. Individual responses and actions to reduce their exposures to extrem e heat can also substantially ameliorate adverse health impacts (McGeehin and Mirabelli, 2001). Successfully motivating individuals to respond appropriately can therefore decrea se vulnerability and reduce health impacts -- a key goal of public heal th efforts (McGeehin and Mirabelli, 2001).

1.4.5 Institutions
The ability to respond to climate change and reduce vulnerability is influenced by social
institutions as well as the so cial factors noted above. Institu tions are viewed broadly in

1 - 20SAP 4.6 Chapter 1: Introduction

the climate change context and include a wide diversity of things such as regulations, rules and norms that guide behavior. Exampl es include past development and land use patterns, existing environmental and coastal laws; building codes, and legal rights.
Institutions also can determine a decision-ma ker’s access to information and the ways in which the information can be used (Moser et al. , 2007).

Well-functioning institutions are essential to a modern society and provide a mechanism for stability in otherwise volatile environments (Moser et al. , 2007). Future options for responding to future climate impacts are thus shaped by our past and present institutions and how they evolve over time. In addition, th e complex interaction of issues expected with climate change may require new a rrangements and collaborations between institutions to address risks effectively, thereby enhancing adaptive capacity (Grambsch and Menne, 2003). A number of institutional ch anges have been iden tified that improve adaptive capacity and reduce vulnerability (s ee Chapter 3 for additional details). While the importance of institutions is clear, there are few s cenarios which incorporate an explicit representation of them.

1.4.6 Interacting Effects
The same social and economic systems that b ear the stress of clim ate change also bear
the stress of non-climate fact ors, including: air and wa ter pollution, the influx of immigrants, and an aging and over-burdene d infrastructure in rapidly-growing metropolitan centers and coastal zones. While non-climate stressors are currently more pronounced than climate impacts, one cannot assume that this trend will persist. Understanding the impacts of climate change an d variability on health and quality of life assumes knowledge of how these dynamics might vary by location and across time and socioeconomic group. The effects of climate change often spread from directly affected
areas and sectors to other areas and sect ors through complex li nkages. The relative importance of climate change depends on the directness of each climate impact and on demographic, social, economic, institutional, and political factors, including, the degree of emergency preparedness.

Consider the damage left by Hurricanes Katr ina and Rita in 2005. Dam age was measured not only in terms of lives and property lost, bu t also in terms of the devastating impacts on infrastructure, neighborhoods, businesses, schools, and ho spitals as well as in the disruption to families and friends in establis hed communities, with lost lives and lost livelihoods, challenges to psychological well-being, and exacerbation of chronic illnesses. While the aftermath of a single hurri cane is not the measure of climate change, such an event demonstrates the disruptive power of climate impacts and the resulting tangle of climate and non-climate stressors that complicate efforts to respond and to adapt. Certainly, the impacts following these hur ricanes reveal that socioeconomic factors and failures in human systems may be as damaging as the storms themselves.

Another trend of significance for climate ch ange is the suburbanization of poverty. A recent study noted that b y 2005 the number of low income households living in suburban communities had for the first time surpassed th e number living in central cities (Berube and Kneebone, 2006). Although the poverty rate in cities was still double the suburban rate, there were 1 million more people living in poverty in America’s suburbs. Many of

1 - 21SAP 4.6 Chapter 1: Introduction

these people live in older inner-ring suburbs developed in the 1950’s and 60’s. The climate adaptation challenge for these places is captured succinctly by a recent study: “Neither fully urban nor completely suburban, America's older, inner- ring, "first" suburbs have a unique set of challenges—such as concentrations of elderly and immigrant populations as well as outmoded housing and commercial buildings—very different from those of the center city and fa st growing newer places. Yet fi rst suburbs exist in a policy blind spot with little in the way of state or federal tools to help them adapt to their new realities” (Puentes and Warren, 2006).



### 1.5 Reporting Uncertainty in SAP 4.6

Uncertainty can be traced to a variety of s ources: (1) a misspecification of the cause(s),
such as the omission of a causal factor resulting in spurious correlations; (2) mischaracterization of the effect(s), such as a model that predicts cooling rather than warming; (3) absence of or imprecise measur ement or calibration (such as devices that fail to detect minute causal agen ts); (4) fundamental stochast ic (chance) processes; (5) ambiguity over the temporal ordering of cause and effect; (6) time delays in cause and effect; and, (7) complexity where cause and effect between certain factors are camouflaged by a context with multiple causes and effects, feedback loops, and
considerable noise.

A new perspective on the treatment of uncertainty has emerged from the IPCC Third and Fourth Assessment processes 6 . This new perspective sugges ts that uncertainties about projections of climate changes, impacts, and responses include two fundamentally different dimensions. One dimension recognizes that most processes and systems being observed are characterized by inherent variability in outcomes: the more variable the process or system, the greater the uncertainty associated with any attempt to project an outcome. A second dimension recognizes limita tions in our knowle dge about processes and systems.

This report is a summary of th e state of the science on the im pacts of clima te change on human health, human settlements and human welf are. With this focus, the assessment of uncertainty in this report is based on the litera ture and the author t eam’s expert judgment. The considerations in determining confiden ce include the degree of belief within the scientific community that available unders tanding, models, and an alyses are accurate, expressed by the degree of consensus in the available evidence and its interpretation. This can be thought of using two different dime nsions related to consensus. Figure 1.5 represents the qualitatively de fined levels of understanding. It considers both the amount of evidence available in support of findings and the degree of consensus among experts on its interpretation.

6 SAP4.6 follows the Guidance Notes for Lead Authors of the IPCC Fourth Assessment Report on Addressing Uncertainties , produced by the IPCC in July 2005. See http://www.ipcc.ch/pdf/supportingmaterial/uncertainty-guidance-note.pdf for more details.

1 - 22SAP 4.6 Chapter 1: Introduction

Figure 1.5 Considerations in determining confidence

In this report, each chapter author team a ssigned likelihood judgments that reflect their
assessments of the current consensus of the science and the quality and amount of evidence. This represents their expert judgment that the given likelihood impact statement is likely to be true given a specified climatic change. The likelihood terminology and corresponding values used in this report are shown in Table 1.1. As the focus of this report is on impacts, it is impor tant to note that these likelihood statements refer to the impact, not the underlying climatic changes, i.e., the report do es not address whether the specific climatic change is like ly to occur. Nor do the authors attempt an assessment that takes into account a probabi listic accounting of both the likelihood of the climatic change and the impact. The terms define d in Table 1.1 are intended to be used in a relative sense to summarize judgments of th e scientific understanding relevant to an issue, or to express uncertainty in a fi nding where there is no basis for making more quantitative statements.

The application of this appr oach to likelihood estima tes demonstrates some variability across each of the three core chapters (C hapters 2-4). This variability in reporting uncertainty is based on the degree of richne ss of their respective knowledge bases. A relatively more extensive and specific a pplication of likeliho od and state of the knowledge estimates is possible for health im pacts, only a more general approach is
warranted for conclusions about human settle ments, and uncertainty statements about human welfare conclusions are necessarily the least explicit.

1 - 23SAP 4.6 Chapter 1: Introduction



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### 1.7 Tables

Table 1.1 Description of likelihood: probabilistic a ssessment of outcome having occurred or occurring in the future based on quantitative analysis or elicitation of expert views.

Likelihood Terminology Likelihood of the occurrence / outcome Virtually certain > 99% probability Very likely > 90% probability Likely > 66% probability About as likely as not 33 - 66% probability Unlikely < 33% probability Very unlikely < 10% probability Exceptionally unlikely < 1% probability

1 - 36SAP 4.6 Chapter 1: Introduction



### 1.8 Figures

Figure 1.1 Observed trends in annual average (a) temperature ( o F) and (b) precipitation (inches) across the continental United St ates from 1896 to 2006 (Source: NCDC, 2007)

50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.5 55.0 55.5

1896 1916 1936 1956 1976 1996Annual Avg Temperature (degF)

Source: NCDC, 2007 (a)

24 25 26 27 28 29 30 31 32 33 34

1896 1916 1936 1956 1976 1996Annual Avg Precipitation (inches)

Source: NCDC, 2007 (b)

1 - 37SAP 4.6 Chapter 1: Introduction

Figure 1.2 US Population Projections 2000-2100

0 100 200 300 400 500 600 700 800 900 10 00

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100In millions Census 1990 low

Census 1990 mid

Census 1990 high

SRES A1, B1

SRES A2

SRES B2

Data sources: Census Population Projections http://www.census.gov/population/www/projections/natsumT1.html SRES Population Projections: http://sres.ciesin.columbia.edu/tgcia/

1 - 38SAP 4.6 Chapter 1: Introduction

Figure 1.3 Population Pyramids of the US 2000 and 2050 (Interim Projections based on 2000 Census)

-5 -4 -3 -2 -1 0 1 2 3 4 5 0 - 4 5 - 9 10-14 15 - 19 20 - 24 25 - 29 30 - 34 35 - 39 40 - 44 45 - 49 50 - 54 55 - 59 60 - 64 65 - 69 70 - 74 75 - 79 80 - 84

85+

Male

Female

-5 -4 -3 -2 -1 0 1 2 3 4 5

Data source: Census Population Projections http://www.census.gov/ipc/www/usinterimproj/

1 - 39SAP 4.6 Chapter 1: Introduction

Figure 1.4: U.S. Population and Growth Trends with evidence of more pronounced growth projected along the coasts, in urban centers, and in cities in the South and West (NAST, 2001).

1 - 40SAP 4.6 Chapter 1: Introduction

Figure 1.5 Considerations in determining confidence.

High agreement, High agreement, High agreement,
medium evidence much evidence limited evidence

Level of
agreement Medium agreement, Medium agreement, Medium agreement, (on a limited evidence medium evidence much evidence particular finding)

Low agreement, Low agreement, Low agreement,
medium evidence much evidence limited evidence

Amount of evidence (number and quality of independent sources)

Source : IPCC Guidance Notes on risk and uncertainty (2005)

1 - 41

## Synthesis and Assessment Product 4.6

Chapter 2: Effects of Global Change on Human Health

Lead Author : Kristie L. Ebi, ESS, LLC

Contributing Authors: John Bal bus , Environmental Defense; Patr ick L. Kinney, Columbia University; Erin Lipp, University of Georgia; David Mills, Stratus Consulting; Marie S. O’Neill, University of Michigan; Mark Wilson, University of Michigan

2-1SAP 4.6 Chapter 2: Human Health



### Table of Contents

2.1 Introduction ............................................................................................................... ............................. 3

2.2 Observed Climate-Sensitive Health Outcomes in the United States............................................... 4

2.2.1 Thermal Extremes: Heat Waves............................................................................................. ........... 4

2.2.2 Thermal Ex tremes: Co ld Waves.......................................................................................... ........... 6

2.2.3 Extreme Events: Hurric anes, Floods, and Wild fires ........................................................................ 6

2.2.4 Indirect Health Impacts of C limate Ch ange .............................................................................. ..... 8

2.3 Projected Health Impacts of Climate Change in the United States................................................. 15

2.3.1 Heat-Rel ated Mortality................................................................................................. ................ 15

2.3.2 Hurricanes, Floods, Wildfires and Health Impacts ....................................................................... 1 7

2.3.3 Vectorborne and Zoonotic Diseases ..................................................................................... ....... 18

2.3.4 Water- and Foodborne Diseases .......................................................................................... ........ 18

2.3.5 Air Quality Mo rbidity and Mortality .................................................................................... ........ 19

2.4 Vulnerable Regions and Subpopulations..................................................................................... ...... 22

2.4.1 Vulnerable Regions..................................................................................................... .................. 23

2.4.2 Specific Subpo pulations at Risk........................................................................................ ............ 23

2.5 Adaptation ......................................................................................................................................... 26

2.5.1 Actors and Their Roles an d Responsibilities fo r Adaptation ........................................................ 27

2.5.2 Adaptation Measures to Manage C limate Change-Related Health Risks ..................................... 29

2.6 Conclusions ............................................................................................................... ........................... 29

2.7 Expanding the Knowledge Base .............................................................................................. ........... 30

2.8 References ................................................................................................................ ............................ 32

2.9 Boxes..................................................................................................................................................... 57

2.10 Tables.................................................................................................................... ............................... 61

2.11 Figures ................................................................................................................... .............................. 72

2-2SAP 4.6 Chapter 2: Human Health



### 2.1 Introduction

Climate change can affect hea lth directly and indirectly. Di rectly, extreme weather events (floods, droughts, windstorms, fires, and heat waves) can affect the health of Americans and cause significant economic impacts. Indire ctly, climate change can alter or disrupt natural systems, making it possible for vector , water-, and foodborne diseases to spread or emerge in areas where they had been limite d or not existed, or for such diseases to disappear by making areas less hospitable to the vector or pathogen (NRC, 2001).

Climate also can affect the incidence of di seases associated with air pollutants and aeroallergens. 1 (Bernard et al., 2001) The cause-and-e ffect chain from climate change to changing patterns of health outcomes is often complex and incl udes factors such as initial health status, financial resources, effectiven ess of public health programs, and access to medical care. Therefore, the se verity of future impacts will be determined by changes in climate as well as by concurrent changes in nonclimatic factors and by adaptations implemented to reduce negative impacts.

A comprehensive assessment of the potential impacts of climate change on hum an health in the United States was published in 2000. This First National Assessment was undertaken by the U.S. Global Change Resear ch Program. The Health Sector Assessment examined potential impacts and identified rese arch and data gaps to be addressed in future research; results app eared in a special issue of Environmental Health Perspectives (May 2001). The Health Sector Assessment’s c onclusions on the poten tial health impacts of climate change in the United States included:

 Populations in Northeastern and Midwestern U.S. cities are likely to experience the greates t number of illnesses and deat hs in response to changes in summer temperatures (McGeehin and Mirabelli, 2001).

 The health impacts of extreme weather ev en ts hinge on the vulnerabilities and recovery capabilities of the natural environmen t and the local population (Greenough et al., 2001).

 If the climate becom es warmer and more variable, air quality is likely to be affected (Bernard et al., 2001). However, uncertainties in climate models make the direction and degree of change speculative (Bernard and Ebi, 2001).

 Federal and state laws and regulatory programs protect m uch of the U.S. population from waterborne di sease. However, if climat e variability increases,
current and future deficiencies in areas such as watershed protection, infrastructure, and storm drainage systems will probably increase the risk of contamination events (Rose et al., 2000).

 It is unlikely that vector- and rodent-bor ne dise ases will cause major epidemics in the United States if the public health infrastructure is maintained and improved (Gubler et al., 2001).

 Multiple uncertainties preclude any definitive statement on the direction of potential future change f or each of the health outcomes assessed (Patz et al., 2000).

1 Any of various airborne substances, such as polle n or spores, that can cause an allergic response.

2-3SAP 4.6 Chapter 2: Human Health

The assessment further concluded that much of the U.S. population is protected against
adverse h ealth outcomes associated with weat her and/or climate by existing public health and medical care systems, although certai n populations are at increased risk.

This chapter of Synthesis Assessment Product 4.6 updates the Health Sector Assessm ent. It also examines adaptation strategies that ha ve been or are expected to be developed by the public health community in response to the challenges and opportunities posed by climate change. The first section of this chapter focuses on climate-related impacts on human morbidity and mortality from extrem e weather, vector-, water- and foodborne diseases, and changes in air quality. For each health endpoint, th e assessment addresses the potential impacts, populations that are particular ly vulnerable, and research and data gaps that, if bridged, would allow significant ad vances in future assessments of the health impacts of global change. The assessment includes research published from 2001 through early 2007 in the United States or in Canada , Europe, and Australia, where results may provide insights for U.S. populations.

This chapter summarizes the current burden of climate-sensitive health determ inants and outcomes for the United States, before assess ing the potential health impacts of climate change. Two types of studies are assessed. Studi es that increase our understanding of the
associations between weather variables a nd health outcomes raise possible concerns about the impacts of a changi ng climate. A few studies proj ect the burden of health outcomes using scenarios of soci oeconomic and climate change.

It is important to note that the assessme nt focuses on how climate change could affect the future health of Americans. However, the net impact of any cha nges will depend on many other factors, including demographics; populati on and regional vulnera bilities; the future social, economic, and cultural context; ava ilability of resources and technological options; built and natural environments; public health infrastructure; and the availability and quality of health and social services.

The chapter then turns to adaptation to the potential health imp acts of environm ental change in the United States. It also cons iders public health interventions (including prevention, response, and treatment strategies ) that could be revised, supplemented, or implemented to protect human health in response to the challe nges and opportunities posed by global change; and how much adaptation could achieve.



### 2.2 Observed Climate-Sensitive Health Outcomes in the United
States

2.2.1 Thermal Extremes: Heat Waves
Excess deaths occur during heatwaves, on days with higher-than-average temperatures, and in places where summer temperatures vary more or where extreme heat is rare (Braga et al., 2001). Figure 2.1 illustrates that the relation between te mperature and mortality is nonlinear, typically J- or U- shaped, and that increases in mortality occur even below

2-4SAP 4.6 Chapter 2: Human Health

temperatures considered to be extremely hot. This figure wa s created using log-linear regression to analyze 22 years of data on daily mortality and outdoor temperature in eleven U.S. cities (Curriero et al., 2002). Exposure to excessive natural heat caused a reported 4,780 deaths during the period 1979 to 2002, and an additional 1,203 deaths had hyperthermia reported as a contributing factor (CDC, 2005). These numbers are underestimates of the total mortality associat ed with heatwaves because the person filling out the death certificate may not always list heat as a cause. Furthermore, heat can exacerbate chronic health conditions, and seve ral analyses have reported associations with cause-specific mortality, including cardiov ascular, renal, and respiratory diseases; diabetes; nervous system disorders; and other causes not specifically described as heatrelated (Conti et al., 2007; Fouillet et al., 2006; Medina-Ramon et al., 2006). Among the
most well-documented heatwaves in the United States are those that occurred in 1980 (St. Louis and Kansas City, Missouri), 1995 (C hicago, Illinois), and 1999 (Cincinnati, Ohio; Philadelphia, Pennsylvania; and Chicago, Il linois). The highest death rates in these heatwaves occurred in people over 65 years of age.

Less information exists on temperature-relate d morbidity, and those studies that have examined hospital adm issions and temperature ha ve not seen consistent effects, either by cause or by demonstrated coherence with mortality effects where both deaths and hospitalizations were examin ed simultaneously (Kovats et al., 2004; Michelozzi et al., 2006; Schwartz et al., 2004; Semenza et al., 1999).

Age, fitness, body composition, and level of ac tivity are importan t determinants of how the human body responds to exposure to thermal extremes (DeGroot et al., 2006;
Havenith et al., 1995; Havenith et al., 1998; Havenith, 2001). Groups particularly
vulnerable to heat-related mo rtality include the elderly, ve ry young, city-d wellers, those with less education, people on medications such as diuretics, the socially isolated, the mentally ill, those lacking access to ai r conditioning, and outdoor laborers (Diaz et al., 2002; Klinenberg, 2002; McGeehin and Mirabelli, 2001; Semenza et al., 1996; Whitman et al., 1997; Basu et al., 2005; Gouveia et al., 2003; Greenberg et al., 1983; O'Neill et al., 2003; Schwartz, 2005; Jones et al., 1982; Kovats et al., 2004; Schwartz et al., 2004;
Semenza et al., 1999; Watkins et al., 2001). A sociological anal ysis of the 1995 Chicago heatwave found that people living in neighbor hoods without public gathering places and active street life were at highe r risk, highlighting the importa nt role that community and societal characteristics can play in de termining vulnerability (Klinenberg, 2002).

Figure 2.1 Temperature-mortality relative risk functions for 11 U.S. cities, 1973–1994. Northern cities: Boston, Massachusetts; Chicago, Illinois; New York, New York; Philadelphia, Pennsylvania; Baltimore, Mary land; and Washington, DC. Southern cities: Charlotte, North Carolina; Atlanta, Georgia; Jacksonville, Florida; Tampa, Florida; and Miami, Florida. Relative risk is defined as the risk of an event such as mortality relative to exposure, such that the relative risk is a ratio of the probability of the event occurring in the exposed group versus the probability of occurrence in the control (non-exposed) group.

Urban heat islands may increase heat-related h ealth impacts by rais ing air temperatures in
cities 2-10 o F over the surrounding suburban and rural areas due to absorption of heat by

2-5SAP 4.6 Chapter 2: Human Health

dark paved surfaces and buildings, lack of vegetation and trees, heat emitted from buildings, vehicles, and air conditioners, and reduced air flow around buildings (EPA

, 2005; Pinho and Orgaz, 2000; Vose et al., 2004; Xu and Chen, 2004). However, in some regions, urban areas may not experience greater heat-related mortality than in rural areas (Sheridan and Dolney, 2003); few comparisons of this nature have been published.

The health impacts of high temperatures and high air pollution can interact, with the extent of interaction varying by location (Bates, 2005; Goodm an et al., 2004; Goodman et al., 2004; Keatinge and Donaldson, 2001; O'Neill et al., 2005; Ren et al., 2006).

2.2.2 Thermal Extremes: Cold Waves
From 1979 to 2002, an average of 689 repor ted deaths per year (range 417-1,021), totaling 16,555 over the period, were attri buted to exposure to excessive cold
temp eratures (Fallico et al., 2005). Cold also contributes to deaths caused by respiratory and cardiovascular diseases, so the overall mortality burden is likely underestimated.
Factors associated with increased vulnerabi lity to cold include black race (Fallico et al., 2005); living in Alaska, New Me xico, North Dakota, and Montana, or living in milder states that experience rapid temperature cha nges (North and South Carolina) and western states with greater ranges in nighttime temperatures ( e.g., Arizona) (Fallico et al., 2005); having less education (O'Neill et al., 2003); being female or having pre-existing respiratory illness (Wilkinson et al., 2004); lack of protect ive clothing (Donaldson et al., 2001); income inequality, fuel poverty, and lo w residential therma l standards (Healy, 2003); and living in nursing homes (Hajat et al., 2007).

Because climate change is projected to re duce the severity an d length of the winter season (IPCC, 2007a), there is considerable speculation concerning the balance of climate change-related decreases in winter mo rtality compared with increases in summer mortality. Net changes in mortality are di fficult to estimate because, in part, much depends on complexities in the relationship be tween mortality and the changes associated with global change. Few studies have attemp ted to link the epidemiological findings to climate scenarios for the United States, and studi es that have done so have focused on the effects of changes in average temperature, with results dependent on climate scenarios and assumptions of future adaptation. Mo reover, many factors c ontribute to winter mortality, making highly uncertain how clim ate change could affect mortality. No projections have been published for the United States that incorporate critical factors,
such as the influence of influenza outbreaks.

2.2.3 Extreme Events: Hurricanes, Floods, and Wildfires
The United States experiences a wide ra nge of extreme weather events, including hurricanes, f loods, tornadoes, blizzards, winds torms, and drought. Other extreme events, such as wildfires, are strongl y influenced by meteorological conditions. Direct morbidity and mortality due to an event increase with the intensity and duration of the event, and can decrease with advance warning and prep aration. Health also can be affected indirectly. Examples include carbon monoxi de poisonings from portable electric generator use following hurrica nes (CDC, 2006b) and an increas e in gastroenteritis cases among hurricane evacuees (CDC, 2005a). The ment al health impacts (e.g., post traumatic

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stress disorder, depression) of these events ar e likely to be esp eci ally important, but are difficult to assess (Middleton et al., 2002; Russoniello et al., 2002; Verger et al., 2003;
North et al., 2004; Fried et al., 2005; Weisler et al., 2006). However, failure to fully account for direct and indirect health impact s may result in inadequate preparation for and response to future extreme weather events.

Figure 2.2 shows the annual number of deaths attributable to hurricanes in the United States from the 1900 Galveston storm, ( NOAA, 2006), records for the years 1940-2004 (NOAA, 2005a), and a summary of a subset of the 2005 hurricanes (NOAA, 2007). The data shown are dominated by the 1900 Galvesto n storm and a subset of 2005 hurricanes, particularly Katrina and Rita, which toge ther accounted for 1,833 of the 2,002 lives lost to hurricanes in 2005 (NOAA, 2007b). While Ka trina was a Category 3 hurricane and its path was forecast well in advance, there was a secondary failure of the levee system. This illustrates that multiple factors contribute to making a disaster and that adaptation measures may not fully av ert adverse consequences.

From 1940 through 2005 roughly 4,300 lives were lost in the United States to hurricanes. The impact of the 2005 hurricane season is es pecially notable as it doubled the estim ate of the average number of lives lost to hurricanes in the United States over the previous 65

years.

Figure 2.2 Annual Deaths Attributed to Hurric anes in the United States, 1900 and
1940-2005

Figure 2.3 shows the annual number of deaths at tributed to flooding in the United States
from 1940-2005 (NOAA, 2007a). Over this pe riod roughly 7,000 lives were lost.

Figure 2.3 Annual Deaths Attributed to Flood ing in the United St ates, 1940-2005

A wildfire’s health risk is largely a functi on of the population in the affected area and the speed and intensity with which the wildfire moves through those areas. Wildfires can increase eye and respiratory illness es due to fire-related air pollution. Climate conditions affect wildfire incidence and severity in the West (Westerling et al., 2003; Gedalof et al., 2005; Sibold and Veblen, 2006). Between 1987-2003 and 1970-1986, there was a nearly
fourfold increase in the inciden ce of large Western wildfires ( i.e., fires that burned at least 400 hectares) (Westerling et al., 2006). The key driver of this increase was an average increase in springtim e temperature of 0.87°C that affected spring snowmelt, subsequent potential for eva potranspiration, loss of soil mo isture, and drying of fuels (Running, 2006; Westerling et al., 2006). Data providing a time-s eries summary of deaths similar to the data in Figures 2.2 and 2.3 was not identified.

There is a rich body of litera ture detailing the m ental health impacts of extreme weather events. Anxiety and depression, the most co mmon mental health disorders, can be directly attributable to th e experience of the event ( i.e., being flooded) or indirectly during the recovery process ( e.g., Gerrity and Flynn, 1997) . These psychological effects tend to be much longer lasting and can be worse than the physica l effects experienced during an event and its immediate aftermath.

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Extreme events are often multi-strike stressor s, with stress ass ociated with the event itself; the disruption and problems of the rec overy period; and the worry or anxiety about the risk of recurrence of the event (Tapsell et al., 2002). During the recovery period, mental health problems can arise from the problems associated with geographic displacement, damage to the home or loss of familiar possessions, and stress involved with the process of repairing. The full impact often is not appreciated until after people’s homes have been put back in order. For instance, i n the aftermath of Hurricane Katrina in 2005, mental health services in New Orleans were challenged by an increased incidence of serious mental illness, in cluding anxiety, major depressi on, and post-traumatic stress disorder (PTSD). Shortly after Katrina, a Ce nters for Disease Control and Prevention poll found that nearly half of all survey respondent s indicated a need for mental health care, yet less than 2% were receiving professional attention (Weisler et al., 2006).

2.2.4 Indirect Health Impacts of Climate Change

The observation that most vector-, water- or foodborne and/or animal -associated diseas es exhibit a distinct seas onal pattern suggests a priori that weather and/or climate influence
their distribution and incidence. The followi ng sections differentiate between zoonotic and water- and foodborne diseases, alt hough many water- and foodborne diseases are
zoonotic.

2.2.4.1 Vectorborne and Zoonotic (VBZ) Diseases
Transmission of infectious agen ts by blood-feeding arthropods (particular insect or tick species) and/or by non-huma n ve rtebrates (certain rodents, canids, and other mammals) has changed significantly in the United States during the past centur y. Diseases such as rabies and cholera have become less widespr ead and diseases such as typhus, malaria, yellow fever, and dengue fever have larg ely disappeared, primarily because of
environmental modification and/or socio economic development (Philip and Bozeboom, 1973; Beneson, 1995; Reiter, 1996). While incr easing average temperatures may allow the permissive range for Aedes aegypti , the mosquito vector of dengue virus, to move further north in the US, it is unlikely that more cases of dengue fever will be observed because most people are protected while liv ing indoors due to quality housing. Indeed, a recent epidemic of dengue in southern Te xas and northern Mexico produced many cases among the relatively poor Mexicans, and very few cases among Texans (Reiter et al., 1999). At the same time, other diseases repor ted their distribution either because of suitable environmental conditions (including c limate) or enhanced detection (examples include Lyme disease, ehrlichioses, and Hantavirus pulmonary syndrome) or were introduced and are expanding their range due to appropriate climatic and ecosystem conditions (West Nile Virus; e.g., Reisen et al., 2006). Still others are associated with non-human vertebrates that have complex a ssociations with climate variability and human disease ( e.g., plague, influenza). The burden of VB Z diseases in the United States is not negligible and may grow in the futu re because the forces underlying VBZ disease risk simultaneously involve weather/climate, ecosystem change, social and behavioral factors, and larger political-economic forces that are part of globalization. In addition, introduction of pathogens from other regions of the world is a very real threat.

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Few original research articles on climate a nd VBZ diseases have been published in the United States and in other developed temp erate countries since the First N ational Assessment. Overall, these studies provide evidence that climate affects the abundance and distributions of vectors that may carry We st Nile virus, Wester n Equine encephalitis, Eastern Equine encephalitis, Bluetongue virus, and Lyme disease. Climate also may affect disease risk, but sometimes in count er-intuitive ways that do not necessarily
translate to increased disease inciden ce (Wegbreit and Reisen, 2000; Subak, 2003; McCabe and Bunnell, 2004; DeGaetano, 2005; Purse et al., 2005; Kunkel et al., 2006;
Ostfeld et al., 2006; Shone et al., 2006). Changes in other factor s such as hosts, habitats, and human behavior are also important.

2.2.4.2 Waterborne and Foodborne Diseases

Water and foodborne diseases continue to cause significant morb idity in the United States. In 2002, there were 1,330 food -related disease outbreaks (Lynch et al., 2006), 34 outbreaks from recreational water (2004), and 30 outbreaks from drinking water (2004) (Dziuban et al., 2006; Liang et al., 2006). For outbreaks of foodborne disease with known etiology, bacteria ( Salmonella ) accounted for 55% and viruses accounted for 33% (Lynch et al., 2006). Viral associated outbreaks rose from 16% in 1998 to 42% in 2002, primarily due to increases in norovirus (Lynch et al., 2006). In recreational water, bacteria accounted for 32% of outbreaks, parasites (primarily Cryptosporidium ) for 24%, and viruses 10% (Dziuban et al., 2006). Similarly in drinking water outbreaks of known etiology, bacteria were the most comm only identified agent (29%, primarily Campylobacter ), followed by parasites and viruses ( each identified 5% of the time) (2003 – 2004; Liang et al., 2006). Gastroenteritis c ontinues to be the prim ary disease associated with food and water exposure. In 2003 and 2004, gastroenteritis was noted in 48% and 68% of reported recreational and drinki ng water outbreaks, respectively (Dziuban et al., 2006; Liang et al., 2006).

Water- and foodborne disease remain highly underreported ( e.g., Mead et al., 1999). Few people seek m edical attention and of thos e that do, few cases are diagnosed (many pathogens are difficult to detect and identif y in stool samples) or reported. Using a combination of underreporting estimates, passive and active surveillance data, and hospital discharge data, Mead et al. (1999) estimated that over 210 million cases of gastroenteritis occur annually in the United States, including over 900,000 hospitalizations and over 6,000 deaths. More recently, Herikstad et al. (2002) estimated as many as 375 million episodes of diarrhea oc cur annually in the United States, based on a self-reporting study. These numbers far ex ceed previous estimates. Of the total estimated annual cases, just over 39 million can be attributed to a specific pathogen and approximately 14 million are transmitted by food (Mead et al., 1999). While bacteria continue to cause the majority of doc umented foodborne and waterborne outbreaks (Lynch et al., 2006; Liang et al., 2006), the majority of spor adic (non outbreak) cases of disease are caused by viruses (67%; primarily noroviruses), followe d by bacteria (30%, primarily Campylobacter and Salmonella ) and parasites (3%, primarily Giardia and Cryptosporidium ). While the outcome of many gastrointestinal dis eases is mild and self limiting, they can be fatal or significantly decrease fitness in vu lnerable populations, including young children, the immunocompromised, and the elderly. Children ages 1-4

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and older adults (>80 years) each make up mo re than 25% of hospitalizations involving gastroenteritis, but older adu lts contributed to 85% of the asso ciated deaths (Gangarosa et al., 1992). As the U.S. population ages, the ec onomic and public health burden of diarrheal disease will increase proportiona lly without appropria te interventions.

Most pathogens of concern for food- and wa terborne exposure are enteric and transmitted by the fecal-oral rout e. Climate may affect the pathogen directly by influencing its growth, survival, persistence, transmission, or virulence. In addition, there may be important interactions between land-use prac tices and climate variability. For example,
incidence of foodborne disease associated with fresh produce is growing (FDA, 2001; Powell and Chapman, 2007). Storm events and flooding may result in the contamination of food crops (especially produce such as leafy greens and tomatoes) with feces from nearby livestock or feral animals. Therefore, changing climate or environments may alter the transmission of pathogens or affect the ecology and/or habitat of zoonotic reservoirs (NAS, 2001)

Studies in North America (Unite d St ates and Canada) (Fleury et al., 2006; Naumova et al., 2006), Australia (D’Souza et al., 2004), and several countrie s across Europe (Kovats et al., 2004a) report striking similarities in correlations between peak ambient temperatures (controlled for season) and peak in clinical cases of salmonellosis. Over this broad geographic range, yearly peaks in salmone llosis cases occur within 1 to 6 weeks of the highest reported ambient temperatures. M echanisms suggested in clude replication in food products at various stag es of processing (D’Souza et al., 2004; Naumova et al., 2006) and changes in eating habits during warm summer months ( i.e., outdoor eating) (Fleury et al., 2006). Additionally, because Salmonella are well adapted to both host conditions and the environment, they can grow readily even under low nutrient conditions at warm temperatures ( e.g., in water and associated with fruits and vegetables) (Zhuang et al., 1995; Mouslim et al., 2002). Evidence supports the notion that increasing global temperatures will likely increase rates of salmonellosis; however, additional
research is needed to determine the critical drivers be hind this trend ( i.e., intrinsic properties of the pathogen or extrinsi c factors related to human behavior).

The possible effects of increasing temperatures on Campylobacter infectio n rates and patterns cannot be reliably projected. The apparent seasonality of campylobacteriosis
incidence is more variable than salmonellosi s and temperature models are less consistent in their ability to account for the observed in fection patterns. In the northeastern United States, Canada, and the U.K., Camplyobacter infection peaks coincide with high annual daily or weekly temperatures (Louis et al., 2005; Fleury et al., 2006; Naumova et al., 2006). However, in several other European countries, campylobacteriosis rates peak earlier, before high annual temperatures, a nd in those cases temp erature accounts for only
4% of the interannual variability (Kovats, et al., 2005). Pathogenic species of Campylobacter cannot replicate in the environmen t and will not persist long under nonmicroaerophilic conditions, suggesting that high ambient temperatures would not contribute to increased replicati on in water or in food products.

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Leptospirosis is a re-emerging disease in the United States and, given its wide case distribution, high num ber of pathogenic strains an d wide array of hosts, it is often cited as one of the most widespread zoonot ic disease in the world (Meites et al., 2004; WHO, 1999). While it has not been a reportable di sease nationally since 1995, several states continue to collect passive su rveillance data and cases continue to be reported (Katz et al., 2002; Meites et al., 2004). Because increased disease rates are linked to warm temperatures, epidemiological evidence suggest that climate change may increase the
number of cases.

Pathogenic species of Vibrio (primarily V. vulnificus ) account for 20% of sporadic
shellfish-related illn esses and over 95% of deaths (L ipp and Rose 1997; Morris, 2003).
While the overall incidence of illness from Vibrio infections remains low, the rate of infection increased 41% since 1996 (Vugia et al., 2006). Vibrio species are more frequently associated with warm climates ( e.g., Janda et al., 1988; Lipp et al., 2002). Coincident with proliferati on in the environment, human cases also occur during warm temperatures. In the US, the highest case rates occur in the summer months (Dziuban et al., 2006). Given the close associat ion between temperature, th e pathogen, and disease, increasing temperatures may increase the geographic range and disease burdens of Vibrio pathogens ( e.g., Lipp et al., 2002). For example, increasing pr evalence and diversity of
Vibrio species has been noted in northern Atlant ic waters of the United States coincident with warm water (Thompson et al., 2004). Additionally, although most cases of V. vulnificus infection are attributed to Gulf Coast states, this species recently has been isolated from northern waters in the United States (Pfeffer et al., 2003; Randa et al., 2004).

The most striking example of an increased range in pathogen dist ribution and incidence
was docume nted in 2004, when an outbreak of shellfish-associated V. parahaemolyticus was reported from Prince William Sound in Alaska (McLaughlin et al., 2005). V. parahaemolyticus had never been isolated from Al askan shellfish before and it was thought that Alaskan waters were too cold to suppor t the species (McLaughlin et al., 2005). In the period preceding the July 2004 outbreak, water temperatures in the harvesting area consistently exceeded 15 o C and the mean daily water temperatures were significantly higher than in th e prior six years (McLaughlin et al., 2005). This outbreak extended the northern range of oysters known to contain V. parahaemolyticus and cause illness by 1,000 km. Given the well-documen ted association between increasing sea surface temperatures and proliferation of many Vibrio species, evidence suggests that increasing global temperatures will lead to an increased burden of disease associated with
certain Vibrio species in the United States, especially V. vulnificus and V. parahaemolyticus

.

Protozoan parasites, particularly Cryp tosporidium and Giardia , contribute significantly to
waterborne and to a lesser extent foodborne disease burdens in the United States. Both parasites are zoonotic and form environmentally resistant infective stages, with only 10- 12 oocysts or cysts required to cause diseas e. In 1998, 1.2 cases of cryptosporidiosis per 100,000 people were reported in the United St ates (Dietz and R oberts, 2000); the immunocompromised are at particularly high risk (Casman et al., 2001; King and Monis,

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2006). Between 2003 and 2004, of the 30 reporte d outbreaks of gastroenteritis from recreational water, 78.6% were due to Cryptosporidium and 14.3% were due to Giardia (Dzuiban et al., 2006). Giardia has historically been the most commonly diagnosed parasite in the United States; betwee n 1992 and 1997 there were 9.5 cases per 100,000 people (Furness et al., 2000). Both Cryptosporidium and Giardia case reports peak in late summer and early fall, particularly among young er age groups (Dietz and Roberts, 2000;

Furness et al., 2000). For both parasites, peak rates of reported infection in Massachusetts occurred approximately one month after the annual temperature peak (Naumova et al., 2006). The lagged association between peak annu al temperatures and peaks in reported
cases in late summer has been attributed to increased exposure during the summer bathing season, especially in the younger age groups, and to a sli ght lag in reporting (Dietz and Roberts, 2000; Furness et al., 2000; Casman et al., 2001). With increasing global temperatures, an increase in recreati onal use of water can be reasonably expected and could lead to increased exposure am ong certain groups, especially children.

Naegleria fowleri is a free-living amboeboflagellate found in lakes and ponds at warm

tem peratures, either naturally or in thermally polluted bodie s of water. While relatively rare, infections are almost always fatal (Lee et al., 2002) . N. fowleri can be detected in environmental waters at rates up to 50% (Wellings et al., 1977) at water temperatures
above 25 o C (Cabanes et al., 2001). Cases are consistently re ported in the United States; between 1999 and 2000, four cases (a ll fatal) were reported. While N. fowleri continues to be a rare disease, it rema ins more common in the United St ates than elsewhere in the world (Marciano-Cabral et al., 2003). Given its asso ciation with warm water, elevated temperatures could increase this pathogen’s range.

Epidemiologically significant viruses for food and water expo sure include enteroviruses, rotaviruses, hepatitis A virus, and nor ovirus. Viruses account for 67% of foodborne disease, and the vast ma jority of these are due to norovirus (Mead et al., 1999). Rotavirus
accounts for a much smaller fraction of viral foodborne disease (Mead et al., 1999), but is a significant cause of diarrheal diseas e among infants and young children (Charles et al., 2006). Enteroviruses are not reportable and ther efore incidence rates are poorly reflected in surveillance summaries (Khetsuriani et al., 2006). With the exception of hepatitis A (Naumova et al., 2006), enteric viral infection patterns follow consistent year to year trends. Enteroviruses are characterized by peak s in cases in the early to late summer (Khetsuriani et al., 2006), while rotavirus and norovirus infections typically peak in the winter (Cook et al., 1990; Lynch et al., 2006). No studies have been able to identify a clear role for temperature in viral infection patterns.

An analysis of waterborne out breaks associated with drinking water in the United States
between 1948 and 1994 found that 51% of outbreaks occurred following a daily precipitation event in the 90th percentile and 68% occurred when precipitation levels reached the 80th perc entile (Curriero et al., 2001) (Figure 2.4). Similarly, Thomas et al., (2006) found that the risk of waterborne di sease doubled when rainfall amounts surpassed the 93rd percentile. Rose et al., (2000) found that the relatio nship between rainfall and disease was stronger for surface water outbreaks , but the association was significant for both surface and groundwater sources. In 2000, groundwater used for drinking water in

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Walkerton, Ontario was contaminated with E. coli O157:H7 and Campylobacter during rains that surpassed the 60-year event mark for the region and the 100- year event mark in local areas (Auld et al., 2004). In combination with preceding record high temperatures, 2,300 people in a community of 4,800 residents became ill (Hrudey et al., 2003; Auld et al., 2004).

Figure 2.4 Drinking Waterborne Dise ase Outbreak s and 90%-ile Precipita tion Events (a two month lag precedes outbreaks); 1948 – 1994.

Floodwaters may increase the likelihood of c ontaminated drinking water and lead to incidental exposure to sta nding floodwaters. In 1999, Hurricane Floyd hit North Carolina and resulted in severe flooding of mu ch of the eastern portion of the state, including extensive hog farming operations. Residents in the affected areas experienced over twice the rate of gastrointestinal illness following the flood (Setzer and Domino, 2004). Following the severe floods of 2001 in the Mi dwest, contact with floodwater was shown to increase the rate and risk of gastrointes tinal illness, especially among children (Wade et al., 2004); however, consumption of tap water was not a risk factor as drinking water continued to meet all regulatory standards (Wade et al., 2004).

2.2.4.3 Influenza
Influenza may be considered a zoonosis in that pigs, ducks, etc. serve as non-human hosts to the influenza viruses ( e.g., H3N2, H1N1) that normally infect humans (not H5N1). A
number of recent studies evaluated the influenc e of weather and climate variability on the timing and intensity of the annual influen za season in the United States and Europe.
Results indicated that cold winters alone do not predict pneumonia and influenza (P&I)- related winter deaths, even though cold spells may serve as a short-term trigger (Dushoff et al., 2005), and that regional differences in P&I mortality burden may be attributed to climate patterns and to the dominant circulating virus subtype (Greene et al., 2006).
Studies in France and the United States dem onstrated that the magnitude of seasonal transmission (whether measured as mortal ity or morbidity) during winter seasons is significantly higher during years with cold El Niño Southern Oscillation (ENSO) conditions than during warm ENSO years (Flahault et al., 2004; Viboud et al., 2004), whereas a study in California concluded that higher temperatures and El Niño years increased hospital admissions for viral pneumonia (Ebi et al., 2001). In an attempt to better understand the spatio-temporal patt erns of ENSO and influenza, Choi et al., (2006) used stochastic models (mathematical models that take into account the presence of randomness) to analyze California county-sp ecific influenza mo rtality, and produced maps that showed different risks during the warm and cool phases. In general, these studies of influenza further support the impor tance of climate drivers at a global and regional scale, but have not advanced our understanding of underlying mechanisms.

2.2.4.4 Valley Fever
Valley fever (Coccidioidomycosis) is an infectious disease caused by inhalation of the spores of a soil-inhabiting fungus that thri ves during wet periods following droughts. The disease is of public health im portance in the desert southwest. In the early 1990s, California experienced an epidemic of Va lley Fever following five years of drought

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(Kolivras and Comrie, 2003). It s incidence varies seasonally and annually, which ma y be partly due to climatic variations (Koliv ras and Comrie, 2003; Zender and Talamantes, 2006). If so, then climate change could a ffect its incidence a nd geographic range.

2.2.4.5 Morbidity and Mortali ty Due to Changes in Air Quality

Millions of Americans conti nue to live in areas that do not meet the health-based
National A mbient Air Quality Standards (NAAQS ) for ozone and fine particulate matter (PM2.5). Both ozone and PM2.5 have well-documen ted health effects, and levels of these two pollutants have the potential to be influe nced by climate change in a variety of ways.

Ground-level ozone is formed mainly by reac tions that occur in polluted air in the

presence of sunlight. Nitrogen oxides (emitted mainly by burning of fuels) and volatile organic compounds (emitted both by burning of fuels and by evaporation from vegetation and stored fuels, solvents, and other chemical s) are the key precursor pollutants for ozone formation. Ozone formation increases with gr eater sunlight and higher temperatures; it reaches peak concentrations during the warm half of the year, and then mostly in the late afternoon and early eveni ng. Cloud cover and mixing height are two additional meteorological factors that influence ozone con centrations. It has been firmly established that breathing ozone results in short-te rm, reversible decreases in lung function (Folinsbee et al., 1988) as well as inflammation deep in the lungs (Devlin et al., 1991). In addition, epidemiology studies of people livi ng in polluted areas have suggested that ozone may increase the risk of asthma-related hospital visits (Schwa rtz, 1995), premature mortality (Kinney and Ozkaynak, 1991; Bell et al., 2004), and possibly the development of asthma (McConnell et al., 2002). Vulnerability to ozone he alth effects is greater for persons who spend time outdoors during epis ode periods, especia lly with physical exertion, because this results in a higher cumulative dose to th e lung. Thus, children, outdoor laborers, and athletes may be at greater risk than people who spend more time
indoors and who are less active. At a given lung dose, little has been firmly established about vulnerability as a function of age, r ace, and/or existing health status. However, because their lungs are inflamed, asthmatics are potentially more vulnerable than nonasthmatics.

PM2.5 is a far more complex pollutant than oz one, consisting of all airborne solid or liquid particles that share the property of being less than 2.5 m icrometers in aerodynamic
diameter. 2 All such particles are included, re gardless of their si ze, composition, and biological reactivity. PM2.5 has complex origins, including prim ary particles directly emitted from sources and secondary particles that form via atmospheric reactions of precursor gases. Most of th e particles captured as PM2.5 ar ise from burning of fuels, including primary particles such as diesel s oot and secondary partic les such as sulfates and nitrates. Epidemiologic studies have de monstrated associations between both shortterm and long-term average ambient concentrations and a variety of adverse health outcomes including respiratory symptoms su ch as coughing and difficulty breathing,

2 Aerodynamic diameter is defined in a complex way to adjust for variations in shape and density of various particles, and is based on the physical diameter of a water droplet that would settle to the ground at the same rate as the particle in question. For a spherical water particle, the aerodynamic and physical
diameters are identical.

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decreased lung function, aggravated asthma, development of chronic bron chitis, heart attack, and arrhythmias (Dockery et al., 1993; Samet et al., 2000; Pope et al., 1995, 2002, 2004; Pope and Dockery, 2006; Do minici et al, 2006; Laden et al., 2006). Associations have also been reported for increased school absences, hospital admissions, emergency room visits, and premature mortality. Susceptib le individuals include people with existing heart and lung disease, and diabetics, child ren, and older adults. Because the mortality risks of PM2.5 appear to be mediated thr ough narrowing of arteries and resultant heart impacts (Künzli et al., 2005), persons or populations with high blood pressure and/or preexisting heart conditions may be at increased risk. In a study of mortality in relation to long-term PM2.5 concentrations in 50 U.S. cities, individuals without a high school education demonstrated higher concentration/ response functions that those with more education (Pope et al., 2002). This result suggests that low education was a proxy for increased likelihood of engaging in outdoor labor with an associated increase in exposure
to ambient air.

Using a coupled climate-ai r pollution three-dime nsiona l model, Jacobson (2008) compared the health effects of pre-industria l vs. present day atmospheric concentrations
of CO 2 . The results suggest that in creasing concentrations of CO 2 increased tropospheric ozone and PM2.5, which increased mortality by about 1.1% per degree temperature increase over the baseline rate; Jacobson es timated that about 40% of the increase was due to ozone and the rest to particulate ma tter. The estimated mortality increase was higher in locations wi th poorer air quality.

2.2.4.6 Aeroallergens and Allergenic Diseases
Climate change has caused an earlier onset of the spring pollen seas on for several species in North America (Casassa et al., 2007). Although data are li mited, it is reasonable to infer that allergenic diseases caused by polle n, such as allergic rhinitis, also have experienced concom itant changes in seasonality (Emberlin et al., 2002; Burr et al., 2003). Several laboratory studies suggest that increasing CO 2 concentrations and temperatures could increase ragweed pollen production and prolong the ragweed pollen season (Wan et al., 2002; Wayne et al., 2002; Singeret al., 2005; Ziska et al., 2005; Rogers et al., 2006) and increase some plant metabolites that can affect human health (Ziska et al., 2005;
Mohan et al., 2006). Although there are sugge stions that the abunda nce of a few species of airborne pollens has increased due to climate change, it is unclear whether the allergenic content of these pollen type s has changed (Huynen and Menne, 2003; Beggs and Bambrick, 2005). The introduction of new inva sive species associated with climatic and other changes, such as ragweed and poi son ivy, may increase cu rrent health risks. There are no projections of the possible impact s of climate change on allergenic diseases.



### 2.3 Projected Health Impacts of Climate Change in the United
States

2.3.1 Heat-Related Mortality
Determinants of how climate change could al ter heat-related mortality include actual changes in the m ean and variance of future temperatures; factors affecting temperature

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variability at the local scale; demographic and health characterist ics of the population; and policies that affect the social and econom ic structure of communities, including urban design, energy policy, water use, and transportation pl anning. Barring an unexpected and catastrophic economic decline, residential and industrial development will increase over the coming decades, which could increase urban heat islands in the absence of urban design and new tec hnologies to reduce heat loads.

The U.S. population is aging; the percent of the population over age 65 is projected to be 13% by 2010 and 20% by 2030 (over 50 m illion people) (Day, 1996). Older adults are physiologically and socially vulnerable (Khosla and Guntupalli, 1999; Klinenberg, 2002) to hot weather and heatwaves, suggesting th at heat-related mortality could increase.
Evidence that diabetics are at greater risk of heat-relate d mortality (Schwartz 2005), along with the increasing preval ence of obesity and diabetes (Seidell, 2000; Visscher and Seidell, 2001), suggests that reduced f itness and higher-fat body composition may contribute to increased mortality.

Table 2.1 summarizes projections of temperatur e-related mortality either in the United
States or in tem perate countries whose experience is relevant to the United States (Dessai, 2003) (Woodruff et al., 2005) (Knowlton et al., 2007) (CLIMB, 2004; Hayhoe et al., 2004). Similar studies are unde rway in Europe (Kosatsky et al., 2006; Lachowsky and Kovats, 2006). All studies used downscaled projections of future temperature distributions in the geographic re gion of interest. The studies used different approaches to incorporate likely future adaptation, addressing su ch issues as increased availability of air conditioning, heatwave early warning system s, demographic changes, and enhanced services such as cooling shelters and physiological adaptation.

Time-series studies also can shed light on pot ential f uture mortality during temperature extremes. Heat-related mortality has d eclined over the past decades (Davis et al., 2002;
Davis et al., 2003a; Davis et al., 2003b). A similar trend, fo r cold and heat-related mortality, was observed in London over the last century (Carson et al., 2006). The authors speculate that these declines are due to increasi ng prevalence of air-conditioning (in the United States), improved health care, and other factors. These results do not necessarily mean that future increases in heat-related mo rtality may not occur in the United States, as some have claimed (Davis et al., 2004), because the percentage of the population with access to air conditioning is high in most regions (thus with limited possibilities for increasing access). Furthe r, population level declines may obscure persistent mortality impacts in vulnerable groups.

In summary, given the projections of increase s in the frequency, inte nsity, and duration of heatwaves and projected demographic change s, the at-risk population will increase (highly likely). The extent to which mortal ity increases will depend on the effective
im plementation of a range of adaptation options, including heat wave early warning systems, urban design to reduce heat loads, and enhanced services during heatwaves.

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2.3.2 Hurricanes, Floods, Wildfires and Health Impacts

No studies have projected the future health burdens of extreme weather events. There is concern that climate change could in crease the frequency and/or severity of extreme events, including hurricanes, floods, and wildfires.

Theoretically, climate change could increase the frequency and severity of hurricanes by

warm ing tropical seas where hurricanes firs t emerge and gain mo st of their energy (Pielke et al., 2005; Trenberth, 2005; Halverson, 2 006). Controversy over whether hurricane intensity increased over recent decades stem less from the conceptual arguments than from the limitations of ava ilable hurricane incide nce data (Halverson, 2006; Landsea, 2005; Pielke et al., 2005; Trenberth, 2005). Even if climate change increases the frequency and severity of hu rricanes, it will be difficult to definitively identify this trend for some time because of the relatively short and highly variable
historical data available as a baseline fo r comparison. Adding to the uncertainty, some research has projected that climate change could produce future conditions that might hinder the development of Atlantic hurrica nes despite the warming of tropical seas (NOAA, 2007c).

Evidence suggests that the intensity of A tlantic hurricanes and tropical storms has
increased ov er the past few decades. SAP3.3 i ndicates that there is evidence for a human contribution to increased sea surface temperatures in the tropical Atlantic and there is a strong correlation to Atlantic tropical storm frequency, durat ion, and intensity. However, a confident assessment will require further stud ies. An increase in extreme wave heights
in the Atlantic since the 1970s has been observed: consiste nt with more frequent and intense hurricanes (CCSP, 2008).

For North Atlantic hurricanes, SAP3.3 concludes that it is lik ely that wind speeds and

core r ainfall rates will increase (Henderson-Sellers et al., 1998; Knutson and Tuleya, 2004, 2008; Emanuel, 2005). However, SAP3.3 c oncluded that “frequency changes are currently too uncertain for c onfident projection” (CCSP, 2008). SAP3.3 also found that the spatial distribution of hurricanes will likely change. Storm surge is likely to increase due to projected sea level rise, though the de gree to which these will increase has not been adequately studied (CCSP, 2008).

Theoretical arguments for increases in extr eme precipitation and flooding are based on the principles of the hydrological cycle where increasing average tem perature will intensify evaporation and subs equently increase precipitation (Brons tert, 2003; Kunkel, 2003, Senior et al., 2002). Looking at the available data for evidence of a climate change signal, evidence suggests that the number of extreme precipitation events in the United States has increased (Balling Jr. and Cerveny, 2003; Groisman et al., 2004; Kunkel, 2003). However, these results are not as cons istent when evaluated by season or region (Groisman et al., 2004).

Projections of changes in the future incide nce of extreme-precipitation and flooding rely
on the results from general circ ulation models (GC Ms). These models project increases in

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mean precipitation with a di sproportionate increase in the frequency of extreme precip itation events (Senior et al., 2002). Kim (2003) used a re gional climate model to project that a doubling in CO 2 concentrations in roughly 70 years could increase the number of days with at least 0.5 mm of precipitation by roughly 33% across the study’s defined elevation gradients in the wester n United States. Furthermore, the IPCC concluded that it is very likely (>90% certain ty) that trends in extreme precipitation will continue in the 21st century (IPCC, 2007a).

Studies modeling future wildfire incidence in the western United States using GCM outputs project increasingly severe wildfires, me asured both in terms of energy released
and the number of fires that avoid initial cont ainment in areas that GCMs project will be increasingly dry (Brown et al., 2004; Fried et al., 2004). In general, these results suggest
much of the western United States could f ace an increasing wildfire risk from climate change. The apparent exception could be th e Pacific Northwest, including northern California, where GCMs generally project a wetter future.

Factors independent of the impacts of and responses to climate change will affect vulnerability to extrem e events, includi ng population growth, con tinued urban sprawl, population shifts to coastal areas, and differen ces in the degree of community preparation for extreme events (U.S. Census Bureau, 2004).

All else equal, the anticipated demographic changes will inc rease the size of the U.S. population at risk for future extreme weather ev ents (very likely). This raises the potential for increasing total numbers of adverse health impacts from these events, even if the rate these impacts are experienced decreases (where the rate re flects the number of impacts per some standard population size among those actually experienci ng the events).

2.3.3 Vectorborne and Zoonot ic Diseases
Modeling the possible impacts of climate cha nge on VBZ diseases is complex, and few
studies have ma de projections for diseases of concern in the United States. Studies suggest that temperature infl uences the distributions of Ixodes spp. ticks that transmit pathogens causing Lyme disease in the United States (Brownstein et al., 2003) and Canada (Ogden et al., 2006), and tick-borne encepha litis in Sweden (Lindgren et al., 2000). Higher minimum temperatures were ge nerally favorable to the potential of expanding tick distributions and greater local abundance of these vectors. However, changing patterns of tick-borne encephalitis (TBE) in Europe are not consistently related to changing climate (Randolph, 2004a). Climat e change is projected to decrease the geographic range of TBE in areas of lower la titude and elevation as transmission expands northward (Randolph and Rogers, 2000).

2.3.4 Water- and Foodborne Diseases
Several important pathogens that are commonly transmitted by food or water may be susceptible to changes in replication, su rvival, persistence, habitat range, and
transmission under changing climatic and envi ronmental conditions (Table 2.2). Many of these agents show season al infection patterns (ind icating potential underlying environmental or weather control), are capable of survival or growth in the environment,

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or are capable of waterborne transpor t. Factors that may affect these pathogens include changes in temperature, precipita tion, extreme weather events ( i.e., storms), and ecological shifts. While the US has successf ul programs to protec t water quality under the Safe Drinking Water Act and the Clean Wa ter Act, some contamination pathways and routes of exposure do not fall under regulat ory programs (e.g., dermal absorption from floodwaters, swimming in lakes and ponds w ith elevated pathogen levels, etc.).

2.3.5 Air Quality Morbidity and Mortality

The sources and conditions that give rise to elevated oz one and PM2.5 in outdoor air in
the United St ates have been and will conti nue to be affected by global environmental changes related to land use, economic development, and climate change

. Conversions of farmland and forests into housing developmen ts and the infrastructure of schools and businesses that support them change the sp atial patterns and absolute amounts of
emissions from fuel combustion related to transportation, space heating, energy production, and other activities. Resulting vege tation patterns affect biogenic volatile organic compound (VOC) emissions that infl uence ozone production. Conversion of land from natural to man-made also changes the degree to which surfaces absorb solar energy (mostly in the form of light) and later re-radia te that energy as heat , which contributes to
urban heat islands. In addition to their potential for increasing heat-related health effects, heat islands also can influence local producti on and dispersion of air pollutants like ozone
and PM2.5.

It is important to recognize that U.S. E nvironmental Protection Agency adm inisters a well-developed and successful national re gulatory program for ozone, PM2.5, and other criteria pollutants. Although many areas of th e US remain out of compliance with the ozone and PM2.5 standards, there is evidence for gradual improvements in recent years, and this progress can be expected to conti nue with more stringent emissions controls going forward in time. Thus, the influence of climate change on air quality will play out against a backdrop of ongoing regulatory cont rol of both ozone and PM2.5 that will shift
the baseline concentrations of these two important air pollutants. On the other hand, most of the studies that have examined potential fu ture climate impacts on air quality reviewed
below have tried to isolate the climate e ffect by holding precursor emissions constant over future decades. Thus, the focus has been on examining the sensitivity of ozone
concentrations to alternative future climates rather than on attempting to predict actual
future ozone concentrations.

The influence of meteorology on air quality is substantial and well- established (EPRI, 2005), raising the possib ility that changes in c limate could alter patterns of air pollution concentrations. Temperature and cloud cover a ffect the chemical reac tions that lead to ozone and secondary particle formation. Wi nds, vertical mixing, and rainfall patterns influence the movement and dispersion of anthropogenic pollutant emissions in the atmosphere, with generally improved air quali ty at higher winds, mixing heights, and rainfall. The most severe U.S. air pollution episodes occur with atmospheric conditions that limit both vertical and horizontal disper sion over multi-day periods. Methods used to study the influence of climatic factors on air quality range from sta tistical analyses of empirical relationships to inte grated modeling of future air quality resultin g from climate

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change. To date, most studies have been limited to climatic effects on ozone. Additional research is needed on the impacts of clim at e change on anthropogeni c particulate matter
concentrations.

Leung and Gustafson (2005) used regional clim ate simu lations for temperature, solar radiation, precipitation, and stagnation/vent ilation, and projected worse air quality in Texas and better air quality in the Midw est in 2045-2055 compared with 1995-2005. Aw and Kleeman (2003) simulated an episode of hi gh air pollution in southern California in 1996 with observed meteorology and then with higher temperatures. Ozone concentrations increased up to 16% with hi gher temperatures, while the PM2.5 response was more variable due to opposing forces of increased secondary particle formation and more evaporative losses from nitrate particles. Bell and Ellis (2004) showed greater sensitivity of ozone concentrations in the Mi d-Atlantic to changes in biogenic than to changes in anthropogenic emissions. Ozone’s sensitivity to changing temperatures, absolute humidity, biogenic VOC emissions, and pollution boundary conditions on a fine-scale (4 km grid resolution) varied in different regions of California (Steiner et al., 2006).

Several studies explored the impacts of clim ate change alone on future ozone projections.
In a coarse-scale an alysis of pollution ove r the continental United States, Mickley et al., (2004) used the GISS (NASA Goddard Institute for Space Studies) 4x5o model to project that, due to climate change alone (A1b emissi on scenario), air pollution could increase in the upper Midwest due to decreases between 2000 and 2052 in the frequency of Canadian frontal passages that clear away stagnating air pollution episodes. The 2.8x2.8o Mozart global chemistry/climate model was used to explore global background and urban ozone changes over the 21st century in response to climate chan ge, with ozone precursor emissions kept constant at 1990s levels (Murazaki and Hess, 2006). While global background decreased slightly, th e urban concentrations due to U.S. emissions increased.

As part of the New York Climate and H ealth Study, Hogrefe and colleagues conducted local-scale analyses of air pollution impacts of future clim ate changes using integrated modeling (Hogrefe et al., 2004a,b,c; 2005a,b) to examine the impacts of climate and land use changes on heat- and ozone-related heal th impacts in the NYC metropolitan area (Knowlton et al., 2004; Kinney et al., 2006; Bell et al., 2007; Civerolo et al., 2006). The GISS 4x5o was used to simulate hourly mete orological data from the 1990s through the 2080s based on the A2 and B2 SRES scenarios. The A2 scenario assumes roughly double the CO2 emissions of B2. The global climate outputs were downscaled to a 36 km grid over the eastern United States using the MM5 regional climate model. The MM5 results were used in turn as inputs to the CMAQ regional-scale air quality model. Five summers (June, July, and August) in each of four decades (1990s, 2020s, 2050s, and 2080s) were simulated at the 36 km scale. Pollution precu rsor emissions over the eastern United States
were based on U.S. EPA estimates at th e county level for 1996. Compared with observations from ozone monitoring stations, initial projections were consistent with ozone spatial and temporal patterns over th e eastern United States in the 1990s (Hogrefe et al., 2004a). Average daily maximum 8-hour concen trations were projected to increase by 2.7, 4.2, and 5.0 ppb in the 2020s, 2050s, and 2080s, respectively due to climate

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change (Figure 2.5) (Hogrefe et al., 2004b). The influence of climate on m ean ozone values was similar in magnitude to the in fluence of rising global background by the 2050s, but climate had a much greater impact on extreme values than did the global background. When biogenic VOC emissions we re allowed to increase in response to warming, an additional increase in ozone concentrations was projected that was similar in magnitude to that of climate alone (Hogrefe et al., 2004b). Climate change shifted the
distribution of ozone concentrations towards hi gher values, with larger relative increases in future decades (Figure 6).

Figure 2.5 (a) Summertime Average Daily Maximu m 8-hour Ozone Concent rations (ppb) for the 1990s and Changes for the (b) 2020s relative to the 1990s, (c) 2050s relative to the 1990s, and (d) 2080s relative to the 1990s. All are based on the A2
Scenario relative to the 1990s. Five consecut ive summer seasons were simulated in each
decade.

Figure 2.6 Frequency Distributions of Summe r t ime Daily Maximum 8-hr Ozone
Concentrations over the eastern United St ates in the 1990s, 2020s, and 2050s based on
the A2 Scenario.

Projections in Germany also found larger climate im pacts on extreme ozone values (Forkel and Knoche, 2006). Using the IS92a business-as-usual scenario, the ECHAM4 GCM projected changes for the 2030s comp ared with the 1990s; the output was downscaled to a 20 km grid using a modifica tion of the MM5 regional model, which was
in-turn linked to the RADM2 ozone chemistr y model. Both biogenic VOC emissions and soil NO emissions were projected to increa se as temperatures rose. Daily maximum ozone concentrations increased by between 2 and 6 ppb (6-10%) across the study region. The number of cases where daily maximum ozone exceeded 90 ppb increased by nearly four-fold, from 99 to 384.

Using the NYCHP integrated model, PM2.5 concen trations are projected to increase with climate change, with the effects differing by com ponent species, with sulfates and primary PM increasing markedly and with organic and nitrated components decreasing, mainly due to movement of these volatile sp ecies from the particulate to the gaseous phase (Hogrefe et al., 2005b; 2006).

Hogrefe et al., (2005b) noted that “the simulated ch anges in pollutant concentrations

stemm ing from climate change are the result of a complex interaction between changes in transport, mixing, and chemistry that cannot be parameterized by spatially uniform linear regression relationships.” Additional uncer tainties include how population vulnerability, mix of pollutants, housing char acteristics, and activity patte rns may differ in the future. For example, in a warmer world, more people may stay indoors with air conditioners in the summer when ozone levels are highest, decreasing personal exposures (albeit with potential increases in pollution emissions fr om power plants). Baseline mortality rates may change due to medical advances, changes in other risk factors such as smoking and diet, and aging of the population.

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The New York Climate and Health Project examin ed the marginal sensitivity of health to changes in clim ate to project the potential h ealth impacts of ozone in the eastern United States (Knowlton et al., 2004; Bell et al., 2007). Knowlton and colleagues computed absolute and percentage increases in ozone -related daily summer-season deaths in the NYC metropolitan region in the 2050s as compared with the 1990s using a downscaled GCM/RCM/air quality model (Knowlton et al., 2004; Kinney et al., 2006). The availability of county-scale oz one projections made it possible to compare impacts in the urban core with those in outlying areas. In creases in ozone-related mortality due to climate change ranged from 0.4 to 7.0% acr oss 31 counties. Bell and colleagues expanded the analysis to 50 eastern cities and examined both mortality and hospital admissions (Bell et al., 2007). Average ozone concentratio ns were projected to increase by 4.4 ppb (7.4%) in the 2050s; the range was 0.8% to 13.7%. In addition, ozone red alert days could increase by 68%. Changes in health impacts were of corresponding magnitude.

Based on the new research findings publishe d since the previous assessme nt, the following summary statements can be made:

 There is an established but incomp lete level of knowledge suggesting that both ozone and fine particle concentrations may be affected by climate change.

 A substantial body of new evidence on oz one supports the in terpretation that
ozone concentrations would be more likel y to in crease than decrease in the United States as a result of climate change, holding precursor emissions constant.

 Too few data yet exist for PM to draw firm conclusions about the direction or magnitude of climate impacts



### 2.4 Vulnerable Regions and Subpopulations

In adapting the IPCC's definitions 3 to public health, "vulnerab ility" can be defined as the summation of all risk and protective factor s that ultimately determine whether an individual or subpopulation experiences adverse health outcomes, and "sensitivity" can be defined as an individual's or subpopulati on's increased responsiveness, primarily for biological reasons, to a given exposure. Thus , specific subpopulations may experience heightened vulnerability for c limate-related health effects for a wide variety of reasons. Biological sensitivity may be related to the de velopmental stage, presence of pre-existing chronic medical conditions (s uch as the sensitivity of people with chronic heart conditions to heat-related illness), acquire d factors (such as immunity), and genetic factors (such as metabolic enzyme subtypes that play a role in sens itivity to air pollution effects). Socioeconomic factors also play a critical role in altering vulnerability and sensitivity to environmentally-mediated factors. They may alter the likelihood of exposure to harmful agents, interact with biol ogical factors that me diate risk (such as nutritional status), and/or lead to differen ces in the ability to adapt or respond to exposures or early phases of illness and injur y. For public health planning, it is critical to

3 IPCC Second Assessment. Climat e Change 1995. Available at h ttp://www.ipcc.ch/pub/sa(E).pdf.
Accessed 11-12-07.

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recognize populations that may experience synerg istic effects of mu ltip le risk factors for health problems related to climate ch ange and to other temporal trends.

2.4.1 Vulnerable Regions
Populations living in certain regions of the United States ma y experi ence altered risks for specific climate-sensitive health outcomes due to their regions' baseline climate,
abundance of natural resources such as fertil e soil and fresh water supplies, elevation, dependence on private wells for drinking water, or vulnerability to coastal surges or riverine flooding. Some regions' populations may in fact experience multiple climatesensitive health problems simultaneously. One approach to identifying such areas is to map regions currently experiencing increased ra tes of climate-sensi tive health outcomes
or other indicators of increased climate risk, as illustrated in Figure 2.7a-2.7d.

Residents of low-lying coastal regions, which are common locations for hurricane landfalls and flooding, are particul arly vulnerable to the health impacts of clim ate change. Those who live in the Gulf Coast region, for ex ample, are likely to experience increased
human health burdens due to the constellati on of more intense storms, greater sea level rise, coastal erosion, and damage to freshwate r resources and infrastructure. Other coastal areas may also experience the combination of sea level rise chronically threatening water supplies and periodic infrastructure damage fr om more intense storms. Populations in the
Southwest and Great Lakes re gions may experience increased strain on water resources and availability due to climate change. More intense heat waves and heat-related illnesses may take place in regions where extreme heat events already occur, such as interior continental zones of the United States. High- density urban populations will experience heightened health risks, in part due to the heat-island effect. In addition, increased demand for electricity during summers may lead to greater air pollu tion levels (IPCC, 2007b).

Figure 2.7 a-d U.S. maps indicating counties with existing vulnerability to climate sensitive health outcomes: (a) location of hurricane landfalls; (b) extreme heat events, defined by CDC as temperatures 10 or more degrees above the average high temperature for the region and lasting for several weeks; (c) percentage of population over age 65; (d) West Nile Virus cases reported in 2004. Historical disease activity, especially in the case of WNV, is not nece ssarily predictive of future vulnerability.

2.4.2 Specific Subpopulations at Risk
Vulnerable subpopulations may be categorized according to specific health endpoints. (Table 2.3). W hile this is typically the way the scientific literature reports risk factors for adverse health effects, this section discu sses vulnerability for a variety of climatesensitive health endpoints one subpopulation at a time.

2.4.2.1 Children
Children’s small body mass to surface area rati o and other factors ma ke them more vulnerable to heat-related morbidity and mo rtality (AAP, 2000), wh ile their increased breathing rates relative to body size, time spent outdoors, and developing respiratory tracts heighten their sensitivity to harm from ozone air pollution (AAP, 2004). In

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addition, children's relatively naïve immune systems increase the risk of serious consequences from water and foodborne dis eases; specific developmental factors make them more vulnerable to complications from specific severe infections like E Coli
O157:H7. Children's lack of immunity also plays a role in higher risk of mortality from ma laria (CDC, 2004b). Conversely, maternal antibodies to dengue in infants convey increased risk of developing dengue hemorrhagic syndr omes. A second peak of greater risk of complications from dengue appears in children between the ages of 3 and 5 (Guzman and Khouri, 2002).

Children may also be more vulnerable to psyc hological comp lications of extreme weather events related to climate change. Following two floods in Europe in the 1990s, children demonstrated moderate to severe stress symptoms (Becht et al., 1998; cited in Hajat et al., 2003) and long-term PTSD, depression, and dissatisfaction with ongoing life (Bokszanin, 2000; cited in Hajat et al., 2003).

2.4.2.2 Older Adults

Health effects associated with climate cha nge pose significant risk s for the elderly, who
of

ten have frail health and limited mobili ty. Older adults are more sensitive to temperature extremes, particularly heat (Semenza et al., 1996; Medina-Ramon et al., 2006); individuals 65 years of age and older co mprised 72% of the heat-related deaths in the 1995 Chicago heatwave (Whitman et al., 1997). The elderly are also more likely to have preexisting medical conditi ons, including cardiovascular and respiratory illnesses, which may put them at greater risk of exacerbated illness by climate-related events or conditions. For example, a 2004 rapid needs asse ssment of older adults in Florida found that Hurricane Charley exacerbated preexisting, physician-diagnosed medical conditions in 24-32% of elderly households (CDC, 2004a). Also, effects of ambient particulate matter on daily mortality tend to be greates t in older age groups (Schwartz, 1995).

2.4.2.3 Impoverished Populations
Even in the United States, the greatest health burdens related to climate change are likely
to fall on those with the lowest socioeconom ic status (O'Neill et al., 2003a). Most
affected are individuals with in adequate shelter or resources to find alternative shelter in the event their community is disrupted. While quantitative methods to assess the increase
in risk related to these soci al and economic factors are not well-developed, qualitative insights can be gained by examining risk f actors for mortality and morbidity from recent
weather-related extreme events such as the 1995 heatwave in Chicago and Hurricane Katrina in 2005 (Box 2.1).

Studies of heatwaves identify poor housing conditions, including lack of access to air conditioning and liv ing spaces with fewer room s, as significant risk factors for heatrelated mortality (Kalkstein, 1993; Semeza et al., 1996). Higher heat-related mortality
has been associated with socioeconomic i ndicators, such as lacking a high school education and living in poverty (Curriero et al., 2002). Financial stress plays a role, as one study of the 1995 Chicago heatwave found th at concern about the affordability of utility bills influenced individuals to limit air conditioning use (Klinenberg, 2002). The

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risk for exposure and sensitivity to air polluti on is also elevated among groups in a low er socioeconomic position (O'Neill et al., 2003a).

Air conditioning is an important short-term m ethod for prot ecting health, but is not a sustainable long-term adaptation technology because the electricity use is often associated with greenhouse gas emissions and during heatwaves can overload the grid and contribute to outages (O’Neill, 2003c). Furthermore, the elderly with limited budgets and racial minorities are less likely to have access to air conditioning or to use it during hot weather (O’Neill et al., 2005b, Sheridan, 2006). Incentives for and availability of high-efficiency, low energy- demand residential cooling systems, especially among disadvantaged populations, can a dvance health equity and minimize some of the negative aspects of air conditioning.

Another area of concern for impoverished popul ations is the impact that climate change

m ay have on food systems and food supply. In the United States, food insecurity is a prevalent health risk among the poor , particularly poor children (Cook et al., 2007). On a global scale, studies suggest th at climate change is likely to contribute to food insecurity by reducing crop yield, most signi ficantly at lower latitudes, due to shortened growing periods and decreases in water availability (Parry et al., 2005). In the United States, changes in the price of food would likely cont ribute to food insecuri ty to a greater degree than overall scarcity.

The tragic loss of life that occurred after Hurricane Katrina underscores the increased vulnerability of special popul ations and demonstrates that, in the wake of extrem e weather events, particularly t hose that disrupt medical infr astructure and require largescale evacuation, treating indivi duals with chronic diseases is of critical concern (Ford et al., 2006).

2.4.2.4 People with Chronic Conditions and Mobility and Cognitive Constraints
People with chronic medical c onditions have an especially heightened vulnerability for the health impacts of climate change. Extrem e h eat poses a great risk for individuals with diabetes (Schwartz, 2005), and extreme cold has an increased effect on individuals with chronic obstructive pulmonary disease (S chwartz, 2005). People with mobility and cognitive constraints may be at particular risk during heatwave s and other extreme weather events (EPA, 2006). As noted above, those with chronic medical conditions are
also at risk of worsened status as the re sult of climate-related stressors and limited access to medical care during extreme events.

2.4.2.5 Occupational Groups
Certain occupational groups , primarily by virtue of spending their working hours outdoors, are at greater risk of clim ate-relate d health outcomes. Outdoor workers in rural or suburban areas, such as electr icity and pipeline utility worker s, are at increased risk of infection with Lyme Disease, although eviden ce is lacking for greater risk of clinical illness (Schwartz and Goldstein, 1990; Piacentino and Schwartz, 2002). They and other outdoor workers have increased exposures to ozone air pollution and heat stress, especially if work tasks involve heavy exertion.

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2.4.2.6 Recent Migrants and Immigrants
Residential mobility, migration, and immi gration ma y increase vulnerability. For example, new residents in an area may not be acclimated to the w eather patterns, have lower awareness of risks posed by local vect orborne diseases, and have fewer social networks to provide support dur ing an extreme weather event. U.S. immigrants returning to their countries of origin to visit friends and relatives have also been shown to suffer
increased risks of severe trav el-associated diseases (Bacaner et al., 2004, Angell and Cetron, 2005). This vulnerability may become more significant if such diseases, which include malaria, viral hepatitis, and typhoid fe ver, become more prev alent in immigrants’ countries of origin because of climate change.



### 2.5 Adaptation

Realistically assessing the potential health effects of climate change must include consideration of the capac ity to manage new and changing climatic conditions. Individuals, communities, governments, and ot her organizations currently engage in a wide range of actions to identify and preven t adverse health outcomes associated with weather and climate. Although these actions ha ve been largely successful, recent extreme
events and outbreaks of vectorborne di seases highlight areas for improvement (Confalonieri et al., 2007). Climate change is likely to further challenge the ability of current programs and activitie s to control climate-sensitive health determinants and outcomes. Preventing additional morbidity and mortality requires consideration of all upstream drivers of adverse health outcomes, including developing and deploying adaptation policies and measures that consider th e full range of health risks that are likely to arise with climate change.

In public health, prevention is the term analogous to adaptation, acknowledging that adaptation implies a set of c ontinuous or evolving practi ces and not just upfront
investme nts. Public health prevention is cl assified as primary, secondary, or tertiary. Primary prevention aims to prevent the onset of disease in an otherwise unaffected population (such as regulations to reduce harmful exposures to ozone). Secondary prevention entails preventive action in res ponse to early evidence of health effects (including strengthening disease surveillance programs to provide early intelligence on the emergence or re-emergence of health risks at specific locations, and responding effectively to disease outbreaks, such as West Nile virus). Tertiary prevention consists of measures (often treatment) to reduce long- term impairment and disability and to minimize suffering caused by existing disease. In general, primary prevention is more effective and less expensive than secondary and tertiary prevention. For every health outcome, there are multiple possible primar y, secondary, and tertiary preventions.

The degree to which programs and measures will need to be m odified to address the additional pressures due to climate change will depend on factors such as the current burden of climate-sensitive health outcomes, the effectiveness of current interventions, projections of where, when, and how quickly the health burdens could change with changes in climate and climate variability (w hich depends on the rate and magnitude of climate change), the feasibility of implementing additional cost-effective interventions,

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other stressors that could incr ease or decrease resilience to impacts, and the social,

econom ic, and political context within wh ich interventions are implemented (Ebi et al., 2006a). Failure to invest in adaptation may leave communities poorly prepared and increase the probability of severe adverse consequences (Haines et al., 2006a,b).

Adaptation to climate change is basically a risk management issue. Adaptation and mitigation are the p rimary responses to manage current and projected risks. Mitigation and adaptation are not mutually exclusive; co-benefits to human health can result concurrently with implementation of mitig ation and adaptation actions. A dialogue is needed on prioritizing the costs of mitigation actions designed to limit future climate change and the potential costs of continually trying to adapt to its impacts. This dialogue should explicitly recognize that there is no guarantee that future changes in climate will not present a threshold that poses technological or physical limits to which adaptation is not possible.

Adaptation policies and measures should addre ss both projected risks and the regions and populations that currently are not well adapted to climate-re lated health risks. Because the degree and rate of clim ate change is pr ojected to increase over time, adaptation will be a continual process of designing and im plementing policies and programs to prevent adverse impacts from changing expo sures and vulner abilities (Ebi et al., 2006). Clearly, the extent to which effective proactive adaptations are developed and deployed will be a key determinant of future morbidity and mo rtality attributable to climate change.

Regional vulnerabilities to the health imp acts of climate chan ge are influenced by physical, social, demographic, economic, and other factors. Adaptation activities take place within the context of slowly changing factors that are spec ific to a region or population, including specific population and regi onal vulnerabilities, social and cultural factors, the built and natural environment, the status of the public health infrastructure,
and health and social services. Because thes e factors vary across geographic and temporal scales, adaptation policies and measures gene rally are more successful when focused on a specific population and location. Additional important factors include the degree of risk perceived, the human and financial resources available for adaptation, the available technological options, and the politica l will to undertake adaptation.

2.5.1 Actors and Their Roles and Responsibilities fo r Adaptation
Responsibility for the prevention of climate-se nsitiv e health risks rests with individuals, community and state governments, nationa l agencies, and others. The roles and responsibilities vary by health outcome. For example, indi viduals are responsible for taking appropriate action on days with decl ared poor air quality, with health care providers and others responsib le for providing the relevant information, and government agencies providing the regulatory framew ork. Community governments play a central role in preparedness and response for extrem e events because of their jurisdiction over police, fire, and emergency medical services . Early warning systems for extreme events such as heat waves (Box 2.2) and outbreaks of infectious diseases may be developed at the community or state level. The federal gov ernment funds research and development to increase the range of decision support plan ning and response tools. Medical and nursing

2-27SAP 4.6 Chapter 2: Human Health

schools are responsible for ensuring that he alth professionals are trained in the
identifi cation and treatment of climate-se nsitive diseases. The Red Cross and other nongovernmental organizations (NGOs) often play critical roles in disaster response.

Additional research and devel opment are n eeded to ensure that surveillance systems account for and anticipate th e potential effects of climate change. Ensuring that surveillance systems account for and anticipate the potential effects of climate change
will be beneficial. For example, surveillance systems in locations where changes in weather and climate may foster the spread of climate-sensitive pathogens and vectors into new regions would help advan ce our understanding of the as sociations between disease patterns and environmental variables. This knowledge could be used to develop early warning systems that warn of outbreaks be fore most cases have occurred. Increased understanding is needed of how to design these systems wher e there is limited knowledge of the interactions of climate, ecosystems, and infectious diseases (NAS, 2001).

There are no inventories in the United States of the various actors taking action to cope
with clim ate change-related health impacts. However, the growing numbers of city and state actions on climate change show increasin g awareness of the potential risks. As of 1 November 2007, more than 700 cities have signed the U.S. Mayors Climate Protection Agreement ( http://www.seattle.gov/mayor/climate/cpaText.htm ); although this agreement focuses on mitigation through increased energy efficiency, o ne strategy, planting trees, can both sequester CO 2 and reduce urban heat islands. The New England Governors and Eastern Canadian Premiers developed a Climat e Change Action Plan because of concerns about public health associated with degrada tion in air quality, public health risks, the magnitude and frequency of extreme climatic phenomena and availability of water. (NEG/ECP, 2001). One action item focuses on the reduction and/ or adaptation of negative social, economic, and environmental impacts. Activities being undertaken include a long-term phenology study, and studi es on temperature increases and related potential impacts.

Strategies, policies, and measures implem ented by community and state governme nts, federal agencies, NGOs, and other actors can change the context for adaptation by conducting research to assess vul nerability and to identify technological options available for adaptation, implementing programs and ac tivities to reduce vulne rability, and shifting
human and financial resources to address the health impacts of climate change. State and federal governments also can provide guida nce for vulnerability assessments that consider a range of plausible future scenario s. The results of these assessments can be used to identify priority hea lth risks (over time), particul arly vulnerable populations and regions, effectiveness of current adaptati on activities, and modifications to current activities or new activities to implement to address current and future climate changerelated risks.

Table 2.4 summarizes the other ro les and responsibilities of va rious actors for adapting to
climate chan ge. Note that viewing adaptation from a public health perspective results in similar activities being classi fied as primary rather than secondary prevention under different health outcomes. It is not possible to prevent the occurrence of a heatwave, so

2-28SAP 4.6 Chapter 2: Human Health

primary prevention focuses on actions such as developing and enforcing appropriate
infr astructure standards, while secondar y prevention focuses on implementing early warning systems and other activities. For vectorborne diseases, primary prevention refers to preventing exposure to infected vectors; in this case, early warning systems can be considered primary prevention. For most vect orborne diseases, ther e are few options for preventing disease onset once an individual has been bitten.

A key activity not included in this framewor k is research on the associations between
weather / climate and various health outcom es, taking into considera tion other drivers of those outcomes ( e.g., taking a systems-based approach), and projecting how those risks may change with changing w eather patterns. Increased understanding of the human health risks posed by climate change is needed for the design of effective, efficient, and timely adaptation options.

2.5.2 Adaptation Measures to Manage Climate Change-Related Health R isks
Determining where populations are not effectiv ely coping with current climate variability
and extremes facilitates identification of the additional interventions that are needed now. However, given uncertainties in climate change projections, identifying current adaptation deficits is not sufficient to protec t against projected health risks. Adaptation measures can be categorized into legislativ e policies, decision s upport tools, technology development, surveillance and monitoring of he alth data, infrastructure development, and other. Table 2.5 lists some adaptation measur es for health impacts from heatwaves, extreme weather events, vectorborne diseases, waterborne diseases, and air quality. These measures are generic because the local contex t, including vulnerabilities and adaptive capacity, need to be considered in the design of programs and activities to be implemented.

An additional category of measures includes public education and outreach to provide information to the general public and specific vulnerable groups on climate risks to which they may be exposed and appropriate actions to take. Messages need to be specific to the region and group; for example, warnings to senior citizens of an impending heatwave should focus on keeping cool and drinking lots of water. Box 2.3 provides tips for dealing with extreme heatwaves developed by U.S. EPA with assistance from federal, state, local, and academic partners (U.S. EPA, 2006).



### 2.6 Conclusions

The conclusions from this assessment are consistent with those of the First National Assessment: climate change poses a risk for U.S. populations, with uncertainties limiting quantitative projections of th e number of increased injuries, illnesses, and deaths attributable to climate change. However, th e strength and consistency of projections for climatic changes for some exposures of concern to human health suggest that implementation of adaptation actions should commence now (Confalonieri et al., 2007). Further, trends in factors that affect vuln erability, such as a larger and older U.S. population, will increase overall vulnerability to health risk s. At the same time, the capacity of the U.S to implement effective a nd timely adaptation measures is assumed to

2-29SAP 4.6 Chapter 2: Human Health

remain high throughout this century, thus re ducing the likelihood of severe health impacts if appropriate program s and activitie s are implemented. However, the nature of the risks posed by climate change means that some adverse health outcomes may not be avoidable, even with attempts at adaptati on. Severe health impacts will not be evenly distributed across populations and regions, but will be concentrated in the most vulnerable groups.

Proactive policies and measur es should be identified th at im prove the context for adaptation, reduce exposures rela ted to climate variability an d change, prevent the onset of climate-sensitive health outcomes, and increase treatment options. Future community, state, and national assessments of the health impacts of c limate variability and change should identify gaps in adaptive capacity, in cluding where barriers and constraints to implementation, such as governance mechanisms, need to be addressed.

Because of regional variability in the types of health stressors attributable to clim ate change and their associated responses, it is difficult to summarize adaptation at the national level. Planning for adaptation is hindered by the fact th at downscaled climate projections, as well as other climate informati on and tools, are genera lly not available to local governments. Such data and tools are essential for sectors potentially affected by climate change to assess th eir vulnerability and possibl e adaptation options, catalogue, evaluate, and disseminate adaptation measures . Explicit considerati on of climate change is needed in the many programs and research ac tivities within federal, state, and local agencies that are relevant to adaptation to ensure that they have maximum effectiveness and timeliness in reducing future vulne rability. In addition, collaboration and coordination are needed across agencies and se ctors to ensure protection of the American population to the current and projected impacts of climate change.



### 2.7 Expanding the Knowledge Base

Few research and data gaps have been filled since the First National Assessment. An important shift in perspective that occurred since the First National Assessment is a greater appreciation of the complex pathwa ys and relationships through which weather and climate affect health, and the understand ing that many social a nd behavioral factors will influence disease risks and patterns (NRC, 2001). Several research gaps identified in the First National Assessment have been partially filled by studies that address the differential effects of temperature extremes by community, demographic, and biological characteristics; that improve our understan ding of exposure-response relationships for extreme heat; and that project the public he alth burden posed by climate-related changes in heatwaves and air quality. Despite these advances, the body of literature remains small, limiting quantitative projections of future impacts.

Improving our understanding of the linkages be tween climate change and health in the United States, m ay require a wide range of activities along the following lines:

2-30SAP 4.6 Chapter 2: Human Health

 Improve characterization of exposure-re sponse relationships, particularly at regiona l and local levels, including id entifying thresholds and particularly vulnerable groups.

 Collect da ta on the early effects of cha nging weather patterns on climate-sensitive
health outcomes.

 Collect and enhance long -term surveillan ce data on health issues of potential concern, including vectorborne and zoonotic diseases, air quality, pollen and mold counts, reporting of food- and waterborne diseases, morbidity due to temperature extremes, and mental health impacts from extreme weather events.

 Develop quantitative mo dels of possible he alth impacts of climate change that can be used to explore the consequences of a range of socioeconomic and climate
scenarios.

 Increase understanding of the processe s of adaptation, including social and
behavioral dime nsions, as well as the costs and benefits of interventions.

 Evaluate the im plementation of adaptati on measures. For example, evaluation of heatwave warning systems, especially as they become implemented on a wider scale (NOAA, 2005), is needed to un derstand how to motivate appropriate
behavior.

 Understand local and regional scale vulne rabi lity and adaptive capacity to characterize the potential risks and th e time horizon over which climate risks might arise; these assessments should incl ude stakeholders to ensure their needs
are identified and addressed in subsequent research and adaptation activities.

 Improve comprehensive estimates of the co-benefits of adaptation and mitigation policies in order to clarif y trade-offs and synergies.

 Improve collaboration across the multiple agencies and organizations with responsibility and research re lated to clim ate change-rela ted health impacts, such as weather forecasting, air and water quality regulations, vector control programs, and disaster preparation and response.

 Anticipate infrastructure requirements that will be needed to protect against

extrem e events such as heatwaves, and f ood- and waterborne di seases, or to alter urban design to decrease heat islands, and to maintain drinking and wastewater
treatment standards and source wa ter and watershed protection.

 Develop downscaled climate projections at the local and regional scale in order to conduct the types of vulnera bility and adaptation asse ssm ents that will enable adequate response to climate change and to determine the potential for
interactions between climate and othe r risk factors, including societal, environmental, and economic. The grow ing concern over impacts from extreme events demonstrates the importance of climate models that allow for stochastic generation of possible future events, to assess not only how disease and pathogen population dynamics might respond, but also to assess whether levels of preparedness are likely to be adequate.

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### 2.9 Boxes

Box 2.1 Vulnerable Populations and Hurricane Katrina

In 2005, Hurricane Katrina caused more than 1,500 deaths along the Gulf Coast, and many of these victims were members of vul nerable subpopulations, such as hospital and nursing-home patients, older adults who require d care within their homes, and individuals with disabilities (U.S. CHSGA, 2006). The hur ricane was complicated by a catastrophic failure of the levee system that was intended to shield those areas in New Orleans that lie at or below sea level. According to the L ouisiana Department of Health and Hospitals,
more than 45% of the state's identified vict ims were 75 years of age or older; 69% were above age 60 (LDHH, 2006). In Mississippi, 67% of the victims whose deaths were directly, indirectly, or possibl y related to Katrina were 55 ye ars of age or older (MSDH, 2005).

At hurricane evacuation centers in Louisiana, Mississippi, Arkansas, and Texas, chronic illness was the most commonly reported hea lth problem, accounting for 33% or 4,786 of 14,531 visits (CDC, 2006a). Six of the fifteen de aths indirectly related to the hurricane
and its immediate aftermath in Alabama were associated with preexisting cardiovascular disease (CDC, 2006c), and the storm disrupt ed an estimated 100,000 diabetic evacuees across the region from obtaining appr opriate care and medication (Cefalu et al., 2006). One study suggested that the hurricane had a negative effect on reproductive outcomes among pregnant women and infants, who expe rienced exposure to environmental toxins, limited access to safe food and water, psychol ogical stress, and disrupted health care (Callaghan et al., 2007). Other vulnerable individuals included those without personal means of transportation and poor residents in Louisiana and Mississi ppi who were unable to evacuate in time (U.S. CHSGA, 2006).

2-57SAP 4.6 Chapter 2: Human Health

Box 2.2 Heatwave Early Warning Systems

Projections for increases in the frequency, intensity and duration of heatwaves suggests more cities need heatwave early warning systems, including forecasts coupled with effective response options, to warn the public about the risks during such events (Meehl and Tebaldi 2004). Prevention programs designed to reduce the toll of hot weather on the public have been instituted in several cities, and guidance has been developed to further aid communities seeking to plan such inte rventions, including buddy systems, cooling centers, and community preparedness (EPA 2006b). Although these systems appear to reduce the toll of hot weather (Ebi et al., 2004; Ebi and Schmier 2005; Weisskopf et al., 2002), and enhanced preparedness following events such as the 1995 heatwaves in Chicago and elsewhere, a survey of individuals 65 or older in four North American cities (Dayton, OH; Philadelphia, PA; Phoenix, AZ ; and Toronto, Ontario, Canada) found that the public was unaware of appropriate prev entive actions to take during heatwaves (Sheridan 2006). Although respondents were awar e of the heat warnings, the majority did not consider they were vulnerable to the he at, or did not consider hot weather to pose a significant danger to their health. Only 46% m odified their behavior on the heat advisory days. Although many individuals surveyed ha d access to home ai r-conditioning, their use of it was influenced by concerns about ener gy costs. Precautionary steps recommended during hot weather, such as increasing intake of liqui ds, were taken by very few respondents (Sheridan 2006). Some responde nts reported using a fan indoors with windows closed and no air-conditioning, a situat ion that can increase heat exposure and be potentially deadly. Further, simultaneous he at warnings and ozone alerts were a source of confusion, because recommendations not to drive conflicted with the suggestion to
seek cooler locations if the residence was too warm. Critical evaluation is needed of heatwave early warning systems, includi ng which components are effective and why (Kovats and Ebi 2006; NOAA 2005).

2-58SAP 4.6 Chapter 2: Human Health

Box 2.3: Quick Tips for Responding to Excessive Heat waves

For the Public
Do

• Use air conditioners or spend time in air-conditioned locations such as malls and
libraries

• Use portable electric fans to exhaust hot air from rooms or draw in cooler air

• Take a cool bath or shower

• Minimize direct exposure to the sun

• Stay hydrated – regularly drink wate r or other nonalcoholic fluids

• Eat light, cool, easy-to-digest foods such as fruit or salads

• Wear loose fitting, li ght-colored clothes

• Check on older, sick, or fr ail people who may need he lp responding to the heat

• Know the symptoms of excessive heat e xposure and the appropriate responses.
Don’t

• Direct the flow of portable electric fans toward yourself when room temperature
is hotter than 90°F

• Leave children and pets alone in cars for any amount of time

• Drink alcohol to try to stay cool

• Eat heavy, hot, or hard-to-digest foods

• Wear heavy, dark clothing.

Useful Community Interventions For Public Officials Send a clear public message

• Communicate that EHEs [extreme heat ev ent] are dangerous and conditions can be life-threatening. In the event of conflicting environmental safety recommendations, emphasize that health pr otection should be the first priority. Inform the public of anticipated EHE conditions

• When will EHE conditions be dangerous?

• How long will EHE conditions last?

• How hot will it feel at specific times during the day ( e.g., 8 a.m., 12 p.m., 4 p.m., 8 p.m.)? Assist those at greatest risk

• Assess locations with vuln erable populations, such as nursing homes and public housing

• Staff additional emergency medical personne l to address the anticipated increase
in demand

• Shift/expand homeless in tervention services to cover daytime hours

• Open cooling centers to offer relief for people without air conditioning and urge the public to use them.
Provide access to additional sources of information

• Provide toll-free numbers and Web site ad dresses for heat exposure symptoms and responses

• Open hotlines to report concerns about individuals who may be at risk

2-59SAP 4.6 Chapter 2: Human Health

• Coordinate broadcasts of EHE response information in newspapers and on
television and radio.

Source: U.S. EPA, 2006

2-60SAP 4.6 Chapter 2: Human Health

2-61 The impacts projected for Lisbon were more sens itive to the choice of regional climate model
than the method used to calculate excess deaths , and the author described the challenge of extrapolating health effects at the high end of the temperature distribution, for which data are sparse or nonexistent (Dessai 2003). Table 2.1 Projections of Impacts of Clim ate Change on Heat-Related Mortality 

### 2.10 TablesSAP 4.6 Chapter 2: Human HealthTable 2.2. Possible Influence of Climate Change on Climate Susceptible Pathogens and/or Disease, Based on ObservationalModels or Empirical EvidencePathogenClimate RelatedDriverPossible Influence of Climate ChangeLikelihoodof ChangeaBasis for AssessmentReferencesBacteriaSalmonellaRising TemperatureIncreasing temperature associated withincreasing clinical casesLikelyLikelihood of climate eventishigh and publishedresearch supports diseasetrendD’Souzaet al.,2004;Kovatset al.,2004a;Fleuryet al.,2006;Naumovaet al.,2006Changes inPrecipitationPrecipitation and run-off associated withincreasedlikelihood of contamination ofsurface waters used for recreation, drinkingor irrigation.LikelyLikelihood of climate eventis probable but moreresearch is needed toconfirm disease trendHaley 2006;Holleyet al.,2006Shifts in ReservoirHost RangesShifts in habitat and range of reservoir hostsmay influence exposure routes and/or rate ofcontact with humansMore likelythannotLikelihood of climate eventis probable but there isinsufficient research on thisrelationshipSrikantiahet al.,2003CampylobacterRising TemperatureIncreasing temperatures may expand typicalpeak season of clinical infection, or result inearlier peak (commonly spring and summer)More likelythannotLikelihood of climate eventishigh and publishedresearch supports diseasetrend, but mechnisms arenot understoodSkelly & Weinstein,2003; Louiset al.,2005; Kovatset al.,2005Increasing temperatures may result in shorterdevelopmental times for flies, contributing toincreased transmission by this proposedvectorAbout aslikely as notLikelihood of climate eventand fly development trend ishigh but additional researchis needed to confirm diseaseassociationNichols, 20052-62SAP 4.6 Chapter 2: Human HealthChanges inPrecipitationIncreasing precipitation and run-offassociated with increasedlikelihood ofcontamination of surface waters used forrecreation or drinkingMore likelythannotLikelihood of climate eventis probable but moreresearch is needed toconfirm disease trendAuldet al.,2004;Vereenet al.,2007Shifts in ReservoirHost Ranges orBehavoirShifts in habitat and range of reservoir hosts(geographically or temporally) may influenceexposure routes and/orrate of contact withhumansMore likelythannotLikelihood of climate eventis probable but there isinsufficient research on thisrelationshipStanleyet al.,1998;Lacey, 1993; Southernet al.,1990VibriospeciesRising TemperatureIncreasingambient temperatures associatedwith growth in pre-harvest and post-harvestshellfish (in absence of appropriate postharvest controls) and increasing diseaseVery likelyLikelihood of climate eventis high and evidencesupports growth trend inambient waters; adaptive(control) measures(refrigeration) would reducethis effect for post-harvestoystersCook, 1994Increasing temperature associated withhigher environmental prevalence and diseaseExtremelylikelyLikelihood of climate eventis highand evidence issupports environmentalgrowth trendJandaet al.,1988;Lippet al.,2002;McLaughlinet al.,2005; Dziubanet al.,2006Increasing temperature associated with rangeexpansionVery likelyLikelihood of climate eventishigh and evidencecollected to date supportstrend; more data needed toconfirmMcLaughlinet al.,2005ChangesinPrecipitationIncreasing precipitation and fresh water runoff leads to depressed estuarine salinities andincrease in someVibriospeciesAbout aslikely as notLikelihood of climate eventis probable but additionalresearch is needed toconfirm pathogendistribution patternsLippet al.,2001b;Louiset al.,2003Sea Level ChangesRising sea level and or storm surge increaserange and human exposureLikelyLikelihood of climate eventis probable but confirmatoryLobitzet al.,20002-63SAP 4.6 Chapter 2: Human Healthresearch is needed ondisease patternsLeptospiraRising TemperatureIncreasing temperatures may increase rangeofpathogen (temporally and geographically)LikelyLikelihood of climate eventis highbut additionalresearch is needed toconfirm pathogendistribution patternsBhartiet al.,2003;Howell and Cole, 2006ChangesinPrecipitationIncreasing precipitation and run off precedesoutbreaksLikelyLikelihood of climate eventinprobable and researchsupports this patternMeiteset al.,2004VirusesEnterovirusesRising TemperatureIncreasing temperature associated withincreased or expandedpeak clinical season(summer)UnlikelyLikelihood of climate eventis high but no mechanisticstudies are available toexplain the underlying causeof this seasonality.Khetsurianiet al.,2006Increasing temperature associated withincreaseddecay and inactivation of viruses inthe environmentAbout aslikely as notLikelihood of climate eventis high and researchdemonstrates decreasedpersistence under increasingtemperatures but little dataare available to relate thiswith diseaseGantzeret al.,1998;Wetzet al.,2004ChangesinPrecipitationIncreasing precipitation associated withincreasedloading of viruses to water andincreased exposure or diseaseLikelyLikelihood of climate isprobable and researchsupports this patternLippet al.,2001a;Frostet al.,2002;Fonget al.,2005NorovirusRising TemperatureIncreasing temperature leads to decreasedretention of virus in shellfishUnlikelyLikelihood of climate eventis high and researchindicates seasonally highshellfish loading in winterbut there is no evidence fordirect control of temperatureon seasonality of infectionBurkhardt and Calci,2000Increasing temperature associated withshorter peak clinical season (winter)UnlikelyLikelihood of climate eventis high and researchindicates seasonal diseasepeak in winter but there isMountset al.,20002-64SAP 4.6 Chapter 2: Human Healthno evidence for directcontrol of temperature onseasonality of infectionIncreasing temperature associated withincreaseddecay and inactivation of viruses inthe environmentAbout aslikely as notLikelihood of climate eventis high and researchdemonstrates decreasedpersistence under increasingtemperatures but little dataare available to relate thiswith diseaseGriffinet al.,2003ChangesinPrecipitationIncreasing precipitation associated withincreasedloading of viruses to crops andfresh produceMore likelythannotLikelihood of climate eventis probable but there isinsufficient research on thisrelationshipMiossecet al.,2000Increasing precipitation associated withincreasedloading of viruses to water andincreased exposure or diseaseLikelyLikelihood of climate isprobable and researchsupports this patternGoodmanet al.,1982RotavirusRising TemperatureIncreasing temperature associated withincreased decay and inactivation of viruses inthe environmentAbout aslikely as notLikelihood of climate eventis high and researchdemonstrates decreasedpersistence under increasingtemperatures but little dataare available to relate thiswith diseaseRzezutka and Cook,2004Dampening of winter seasonal peak intemperate latitudesAbout aslikely as notLikelihood of climate eventis high and researchindicates seasonal diseasepeak in winter but there isno evidence for directcontrol of temperature onseasonality of infection;although tropical countriesdo not exhibit a seasonalpeakCooket al.,1990ParasitesNaegleriafowleriRising TemperatureIncreasing temperature associated withexpanded range and conversion to flagellatedMore likelythannotLikelihood of climate eventis high but more research isCabaneset al.,20012-65SAP 4.6 Chapter 2: Human Health2-66form (infective)needed to confirm diseasetrendCryptosporidiumRising TemperatureExpanding recreational (swimming) seasonmay increase likelihoodofexposure anddiseaseAbout aslikely as notLikelihood of climate eventis high but there isinsufficient research on thisrelationshipNaumovaet al.,2006Changes inPrecipitationIncreasing precipitation associated withincreasedloading of parasite to water andincreased exposure and diseaseVery likelyLikelihood of climate eventis probable and researchsupports this pattern butadaptive measures (watertreatment and infrastructure)would reduce this effectCurrieroet al.,2001;Davieset al.,2004GiardiaRising TemperatureExpanding recreational (swimming) seasonmay increase likelihoodofexposure anddiseaseAbout aslikely as notLikelihood of climate eventis high but there isinsufficient research on thisrelationshipNaumovaet al.,2006Changes inPrecipitationIncreasing precipitation associated withincreasedloading of parasite to water andincreased diseaseVery likelyLikelihood of climate eventis probable and researchsupports this pattern butadaptive measures (watertreatment and infrastructure)would reduce this effectKistemannet al.,2002Shifts in ReservoirHost Ranges orBehavoirIncreasing temperature associated withshiftingrange in reservoir species (carriers)and expanded disease rangeAbout aslikely as notLikelihood of climate eventis probable but there isinsufficient research on thisrelationshipParkinson and Butler,2005aLikelihood was based on expertjudgment of the strength of the research and the likelihood ofthe event. See Chapter 1 for adiscussion of likelihood (section 1.5).SAP 4.6 Chapter 2: Human Health

2-67 Table 2.3. Climate-Sensitive Health Ou tcomes and Particularly Vulnerable Groups

Climate-Sensitive Health
Outcome Particularly Vulnerable Groups

Heat-Related Illnesses and
Deaths Elderly, chronic medical conditions, infants and children, preg nant wom en, urban and rural poor,
outdoor workers
Diseases and Deaths Related to Air Quality Children, pre-existing heart or lung disease, diabetes, athletes, outdoor workers
Illnesses and Deaths Due to
Extreme Weather Events Poor, pregnant women, chronic medical conditions,

m obility and cognitive constraints

Water- and Foodborne Illness Immunocompromised, elderly, infants; specific risks for specific cons equences ( e.g., Campylobacter and Guillain-Barre syndrome, E. coli O157:H7)
Vectorborne Illnesses
A. Lyme Disease Children, outdoor workers

B. Hantavirus Rural poor, occupational groups
C. Dengue Infants, elderly

D. Malaria Children, immunocompromised, pregnant women, genetic ( e.g., G6PD status)SAP 4.6 Chapter 2: Human HealthTable 2.4: Actors and Their Roles and Responsibilities for Adaptation to Climate Change Health RisksActorReduceExposuresPreventOnset of Adverse HealthOutcomesReduce Morbidity and MortalityExtreme Temperature and Weather EventsIndividualsStay informed about impending weathereventsFollow guidance for emergencypreparednessFollow guidance for conduct during andfollowing anextreme weather event (such asseeking cooling centers during a heatwaveor evacuation during a hurricane)Seek treatment when neededCommunity,State, andNationalAgenciesProvide scientific and technicalguidance forbuilding and infrastructurestandardsEnforce building and infrastructurestandards, includingidentification ofrestricted building zones wherenecessaryDevelop scientific and technical guidanceand decisions support toolsfor developmentof early warning systems and emergencyresponse plans, including appropriateindividual behaviorImplement early warning systems andemergency response plansConduct tests of early warning systems andresponse plans before eventsConduct education and outreach onemergency preparednessEnsure that emergencypreparedness plansincludemedicalservicesImprove programs to monitor theair, water, and soil forhazardousexposuresImprove surveillance programs tocollect, analyze, and disseminatedata on the health consequences ofextreme events and heatwavesMonitor and evaluate theeffectiveness ofsystemsNGOs and OtherActorsNGOs and other actors play critical roles inemergency preparedness and disaster reliefEducation and training of healthprofessionals on risks fromextreme weather eventsVectorborne and Zoonotic DiseasesIndividualsTake appropriate actions to reduceexposure to infected vectors, includingeliminating vector breeding sites aroundresidenceVaccinate for diseases to which one wouldlikely be exposedSeek treatment when needed2-68SAP 4.6 Chapter 2: Human HealthCommunity,State, andNationalAgenciesProvide scientific and technicalguidance anddecision support tools fordevelopment of early warning systemsConduct effective vector (and pathogen)surveillance and control programs(including consideration of land usepolicies that affect vector distributionand habitats)Develop early warning systems fordisease outbreaks, such asWest NilevirusDevelop anddisseminate information onappropriate individualbehavior to avoidexposure to vectorsConduct research on vaccines and otherpreventive measuresConduct research and development on rapiddiagnostic toolsProvide vaccinations to those likelyto beexposedConduct research on treatmentoptionsDevelop and disseminateinformation on signs andsymptoms of disease to guideindividuals on when to seektreatmentWaterborne and Foodborne DiseasesIndividualsFollow proper food-handling guidelinesFollow guidelines on drinking waterfrom outdoorsourcesSeek treatment when neededCommunity,State, andNationalAgenciesImprove surveillance and controlprograms forearly detection of diseaseoutbreaksDevelop methods to ensure watershedprotection and safe water and foodhandling (e.g.,Clean Water Act)Sponsor research and development on rapiddiagnostic tools for food- and waterbornepathogensSponsor research and developmenton treatment optionsDevelop and disseminateinformation on signs andsymptoms of disease to guideindividuals on when to seektreatmentDiseases Related to Air QualityIndividualsFollow advice on appropriate behavioron high ozone daysFor individuals with certain respiratorydiseases, follow medical advice duringperiods of high air pollutionSeek treatment when needed2-69SAP 4.6 Chapter 2: Human HealthCommunity,State, andNationalAgenciesDevelop and enforce regulations of airpollutants (e.g.,Clean Air Act)Develop decision support tools for earlywarning systemsConduct education and outreach on the risksof exposure toair pollutantsConduct research on treatmentoptions2-70SAP 4.6 Chapter 2: Human Health2-71Table 2.5: Adaptation Measures to Reduce Climate Change-Related Health RisksHeatwavesExtremeWeatherEventsVectorborne DiseasesWaterborne DiseasesAir QualityDecisionSupport ToolsEnhance earlywarning systemsEnhance early warningsystems andemergency responseplansEnhance early warningsystems based onclimate andenvironmental data forselected diseasesDevelop early warningsystems based on climateand environmental data forconditions that mayincrease selected diseasesEnhance alertsystems for highair pollutiondaysTechnologyDevelopmentImprove buildingdesign to reduce heatloads duringsummermonthsDevelop vaccines forWest Nile virus andother vectorbornediseasesDevelop more rapiddiagnostic testsDevelop more rapiddiagnostic testsSurveillanceand MonitoringAlter health datacollection systems tomonitor for increasedmorbidity andmortality during aheatwaveAlter health datacollection systems tomonitor for diseaseoutbreaks during andafter an extreme eventEnhance vectorsurveillance and controlprogramsMonitor diseaseoccurrenceEnhance surveillance andmonitoring programs forwaterborne diseasesEnhance healthdata collectionsystems tomonitor for healthoutcomes due toair pollutionInfrastructureDevelopmentImprove urban designto reduce urban heatislands by plantingtrees, increasinggreen spaces, etc.Design infrastructureto withstandprojectedextreme eventsConsider possibleimpacts of infrastructuredevelopment, such aswater storage tanks, onvectorborne diseasesConsider possible impactsof placement of sources ofwater- and foodbornepathogens (e.g.,cattle neardrinking water sources)Improve publictransit systems toreduce trafficemissionsOtherConduct research oneffective approachesto encourageappropriate behaviorduring a heatwaveConduct research oneffective approaches toencourage appropriatebehavior during anextreme eventSAP 4.6 Chapter 2: Human Health



### 2.11 Figures

Figure 2.1. Temperature-mortality relative risk functions for 11 U.S. cities, 1973–1994. Northern cities: Boston, Massachusetts; Chicago , Illinois; New York, New York; Philadelphia, Pennsylvania; Baltimore, Maryland; and Washin gton, DC. Southern cities: Charlotte, North Carolina; Atlanta, Georgia; Jacksonville, Florida; Tampa, Florida; and Miami, Florida. Relative risk
is defined as the risk of an event such as morta lity relative to exposure, such that the relative risk is a ratio of the probability of the even t occurring in the exposed group versus the probability of occurrence in th e control (non-exposed) group.

(Curriero et al., 2002)

2-72SAP 4.6 Chapter 2: Human Health

Figure 2.2. Annual Deaths Attributed to Hurricanes in the United States, 1900 and 1940-2005

1 10 100 1000 10000

1895 1905 1915 1925 1935 1945 1955 1965 1975

1 9 8 5 1995 2005 Galveston, 1900,
~8,000 deaths 2005, Dennis, Katrina,
Rita, and Wilma 2,002

deaths

Source: NOAA, 2007

2-73SAP 4.6 Chapter 2: Human Health

Figure 2.3. Annual Deaths Attributed to Floodin g in the United States, 1940-2005

0 60 120 180 240 300 360 420 480 540 600

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YearAnnual Deaths from Flooding

Source: NOAA, 2007a

2-74SAP 4.6 Chapter 2: Human Health

Figure 2.4. Drinking Waterborne Disease Outbreaks an d 90%-ile Precipitation Events (a two month lag precedes outbreaks); 1948 – 1994.

Source: Curriero et al., 2001

2-75SAP 4.6 Chapter 2: Human Health

Figure 2.5: (a) Summertime Average Daily Maximum 8- hour Ozone Concentrations (ppb) for the 1990s and Changes for the (b) 2020s relative to the 1990s, (c) 2050s relative to the 1990s, and (d) 2080s relative to the 1990s. All are based on the A2 Scenario relative to the 1990s. Five

consecutive summer seasons were simulated in each decade.

Source: Hogrefe et al., 2004a.

2-76SAP 4.6 Chapter 2: Human Health

Figure 2.6. Frequency Distributions of Summe rtime Daily Maximum 8-hr Ozone
Concentrations over the eastern United States in the 1990s, 2020s, and 2050s based on the A2
Scenario.

Source: From Hogrefe et al., 2 005 a

2-77SAP 4.6 Chapter 2: Human Health

Figure 2.7.a-d. U.S. maps indicating counties with existing vulnerability to climate sensitive health outcomes: (a ) location of hurricane landfal ls; (b) extreme heat events, defined by CDC as temperatures 10 or more degrees above the average high temperature for the region and lasting for several weeks; (c) percentage of popul ation over age 65; (d) West Nile Virus cases reported in 2004. Historical disease activ ity, especially in the case of WNV, is not necessarily pr edictive of future vulnerabilit y. Maps were generated using NationalAtlas.gov TM Map Maker (2008).

2-78

## Synthesis and Assessment Product 4.6

Chapter 3: Effects of Global Change on Human
Settlements

Lead Author : Thomas J. Wilbanks, Oak Ridge National Laboratory

Contributing Authors: Paul Kirs he n, Tufts University; Dale Quattrochi, NASA/Marshall Space Flight Center; Patricia Romero-Lankao, NCAR; Cynthia Rosenzweig, NASA/Goddard; Matthias Ruth, University of Maryland; William Solecki, Hunter College; Joel Tarr, Carnegie Mellon University

Contributors: Peter Larsen, Universi ty of Alaska-Anchorage; Brian Stone, Georgia TechSAP 4.6 Chapter 3: Human Settlements



### Table of Contents

3.1 Introduction ...............................................................................................................

............................. 3

3. 1.1 Purpose ............................................................................................................................................. 3

3.1.2 Background ....................................................................................................................................... 3

3.1.3 Current Stat e of Knowl edge ............................................................................................... ............... 4

3.2 Climate Change Impact s and the Vul nerabilities of Human Se ttlements ......................................... 4

3.2.1 Determinants of V u lnerability............................................................................................ ............... 4

3.2.2 Impacts of C limate C h ange on Hu man Settleme nts .......................................................................... 5

3.2.3. The Interaction of Climate Im pacts wit h Non-C limate Factors. ...................................................... 7

3.2.4 Realizing Opportun ities from Climate Change in the Unite d States................................................. 9

3.2.5 Examples of Impacts on Metropo litan A r eas in the United States .................................................. 10

3.3 Opportunities for Adaptation of Hu m a n Settlements to Climate Change ...................................... 10

3.3.1. Perspectives on A d aptation by Settleme nts ............................................................................... ..... 11

3.3.2 Major Categories of A d aptation Strategies................................................................................ ..... 12

3.3.3 Examples of Curre nt A d aptation Strategies.............................................................................. .... 13

3.3.4: Strategies to E n hance Adap tive Ca pacity

................................................................................. ..... 14

3.4. Conclusions ............................................................................................................... ........................... 14

3.5 Expanding the Knowledge Base ...............................................................................................

........... 15

3. 6 References .................................................................................................................

............................ 17

3. 7 Boxes......................................................................................................................

................................ 24

3. 8 Tables..................................................................................................................................................... 29

3.9 Figures ................................................................................................................................................... 31

3-2SAP 4.6 Chapter 3: Human Settlements



### 3.1 Introduction

3.1.1 Purpose
Human settlements are where people live a nd work, including all population centers ranging from small rural communities to densely developed metropolitan areas. This chapter addresses climate change impacts, both positive and negative, on human settlements in the United States. First, the chapter summarizes current knowledge about the vulnerability of human se ttlements to climate change, in a context of concurrent changes in other non-climate factors. Next , the chapter summarizes opportunities within settlements for adaptation to climate change. Finally, the chapter prov ides an overview of recommendations for expanding the current kno wledge base with respect to climate change and human settlements.

3.1.2 Background

Events such as Hurricane Katrina in 2005 and electric power outages during the hot
summer of 2006 have demonstrated how climat e-related events can dramatically im pact U.S. settlements. Climate affects the costs of assuring comfort at home and work. Climate affects inputs for a good life: water, products and services from agriculture and forestry, pleasures and tourist potentials from nature, biodiversity, and outdoor recreation. Climate also affects the presence and spread of diseases and other health problems, and it
is associated with threats from natural disa sters, including floods , fires, droughts, wind, hail, ice, and heat and cold waves.

Some U.S. settlements may find opportunities in climate change. W armer winters are not necessarily undesirable. Periods of change tend to reward forward-looking, effectivelygoverned communities. Considering climate cha nge effects may help to focus attention on other important issues for the long-term sustainable development of settlements and communities. Furthermore, planning for the futu re is an essential part of public policy decision-making in urban areas.

Since infrastructure investments in urban areas are often both large and difficult to reverse, clim ate considerations are increasing ly perceived as one of a number of relevant issues to consider when planning for the future (Ruth, 2006a). If U.S. settlements, especially larger cities, respond effectively to climate change concerns, their actions could have far-reaching implications for hu man well-being, because these areas are where most of the U.S. population lives, la rge financial decisions are made, political influence is often centered, and technologi cal and social innovations take place.

Meanwhile, the pattern of human settlements in the United States is changi ng. In addition to shifts of population from frost-belt to s un-belt settlements, patterns are changing in other ways as well. For instance, what once appeared to be an inexorable spread of
households from urban centers to peripheries is showing renewa l in many city centers as metropolitan areas continue to expand across multiple jurisdictions (Solecki and Leichenko, 2006). Modern information technologi es are enabling people to perform what were historically urban functions from rela tively remote locations (Riebsame, 1997).

3-3SAP 4.6 Chapter 3: Human Settlements

3.1.3 Current State of Knowledge
The current knowledge base provides limited grounds for developing conclusions and
recommendations related to clim ate impact s on human settlements. In many cases, the
best that can be done is to sk etch out the issue “l andscape” that should be considered by both policy-makers and the research community as a basis for further discussion, offering illustrations from the relatively small research literature that is now available.

The fact is that little resear ch has been done to date specif ically on the effects of climate change in U.S. cities and towns. Reasons app ear to include (i) lim itations in capacities to project climate change impacts at the geograp hic scale of a metropolitan area (or smaller) and (ii) the fact that none of the federal agencies currently active in climate science research has a clear responsibility for set tlement impact issues. Improvements in our understanding of the impacts of and adaptation to climate ch ange across different sectors and geographic regions, differe ntial vulnerabilities, and in designing interventions to
build resilience are a ll needed (NRC, 2007).

To some degree, gaps can be filled by referri ng to several co mprehensive analyses that do exist, to literature on effects of climate variation on settlements and their responses, to research on climate change impacts on cities in other parts of the world, and to historical analogs of responses of urban areas to si gnificant environmental changes. A text box
entitled Historical Perspective of the U.S. Urban Responses to Environmental Change is included as Box 3.1. This perspective examines how American cities have been affected by environmental change over the past two centu ries. But this is little more than a place

to start.

At the current state of knowledge, vulnerabilities to possible impacts are easier to project than actual impacts because they estimate risks or opportunities associated with possible consequences rather than estimating the consequences themselves, which requires far
more detailed information about future condi tions. Vulnerabilities are shaped not only by existing exposures, sensitivities, and adap tive capacities but also by the ability of settlements to develop responses to risks

.



### 3.2 Climate Change Impacts and the Vulnerabilities of Human
Settlements

This section examines possible impacts of climate change on settlements in the United States including the determinants of vulnerabi lity to such impacts and how those impacts could affect settlement patterns and vari ous systems related to those patterns.

3.2.1 Determinants of Vulnerability
It has been difficult to project impacts of climate change on h uman settlements in the United States, in part because climate cha nge forecasts are not specific enough for the scale of decision-making (as for other re latively local-scale impact questions) but moreover because climate change is not the on ly change being confr onted by settlements. More often, attention is paid to vulnerabilities to climate change, if those changes should

occur.

3-4SAP 4.6 Chapter 3: Human Settlements

Vulnerabilities to or opportunities from climate change are related to three factors, both
in absolute term s and in comparison to other elements (Clark et al., 2000):

1. Exposure to climate change . To what climate changes are s ettlements likely to be exposed: Changes in temperature or preci pitation? Changes in storm exposures and/or intensities? Changes in sea level?

2. Sensitivity to climate change. If prim ary climate changes occur, how sensitive are the activities and populations of a settlemen t to those changes? For instance, a city dependent substantially on a regional agricultural or forestry economy, or to the availability of abundant water resources, might be considered more sensitive than a city whose economy is based mainly on an industrial sector less sensitive to
climate variation.

3. Adaptive capacity . Fi nally, if effects are experi enced due to a combination of exposure and sensitivity, how able is a se ttlement to handle those impacts without disabling damages, perhaps even wh ile realizing new opportunities?

3.2.2 Impacts of Climate Change on Human Settlements
Impacts of climate change on human settlements vary regionally (see Table 3.2 and Vignettes below), and generally relate to some of the f ollowing issues:

1. Effects on health . It is well-established that high er tem peratures in urban areas are related to higher levels of ozone whic h cause respiratory and cardiovascular problems. There is also some evidence that combined effects of heat stress and air pollution may be greater than simple a dditive effects (Patz and Balbus, 2001). Moreover, historical data show relations hips between mortality and temperature extremes (Rozenzweig and Solecki, 2001a ). Other health concerns include changes in exposure to water and food-bor ne diseases, vector-borne diseases, concentrations of plant species associat ed with allergies, and exposures to
extreme weather events such as stor ms, floods, and fires (see Chapter 2).

2. Effects on water and other urban infrastructures . Changes in precipitation
patterns ma y lead to reductions in meltwat er, river flows, groundwater levels, and
in coastal areas lead to saline intrusion in rivers and groundwater, affecting water supply; and warming may increase water demands (Gleick et al., 2000; Kirshen, 2002; Ruth et al. , 2007). Moreover, storms, flood s, and other severe weather events may affect other infrastruc ture, including sanitation systems, transportation, supply lines for food and energy, and communication. Exposed structures such as bridge s and electricity transmissi on networks are especially vulnerable. In many cases, infrastructure s are interconnected; an impact on one can also affect others (Kirshen, et al. , 2007). An example is an interruption in energy supply, which increases heat st ress for vulnerable populations (Ruth et al.

, 2006a). Many of the infrastructures in ol der cities are aging and are already under stress from increasing demands.

3-5SAP 4.6 Chapter 3: Human Settlements

3. Effects on energy requirements . Wa rming is virtually certain to increase energy demand in U.S. cities for cooling in buildings while it reduces demands for heating in buildings (see SAP 4.5). Dema nds for cooling during warm periods could jeopardize the reliability of servi ce in some regions by exceeding the supply capacity, especially during periods of unus ually high temperatures (see Vignettes in Boxes 3.2 and 3.3). Higher temperatures al so affect costs of living and business operation by increasing costs of clim ate control in buildings (Amato et al. , 2005; Ruth and Lin, 2006c; Kirshen et al. , 2007).

4. Effects on the urban metabolism . An urban area is a living complex megaorganism, associated with a host of i nputs, transformations, and outputs: heat, energy, materials, and others (Decker et al. , 2000). An example is the Urban Heat Index, which measures the degree to which built/paved areas are associated with higher temperatures than surrounding rura l areas (see Box 3.4: Climate Change Impacts on the Urban Heat Island Effect (UHI)). Imbalances in the urban metabolism can aggravate climate change impacts, such as roles of UHI in the formation of smog in cities. The maps in this box demonstrate how the built
environment creates and retains heat in metropolitan settings.

5. Effects on economic competitiven ess, opportunities, and risks. Climate change has the potential not only to affect settlements directly but also to affect them through impacts on other areas linked to their economies at regional, national, and international scales (Rosenzweig and Sol ecki, 2006). In addition, it can affect a settlement’s economic base if it is sensitive to climate, as in areas where settlements are based on ag riculture, forestry, water resources, or tourism (IPCC, 2001b).

6. Effects on social and political structures. Climate change can add to stress on social and political structures by incr easing m anagement and budget requirements for public services such as public health care, disaster risk reduction, and even public security. As sources of stress grow and combine, the resilience of social and political structures that are alrea dy somewhat unstable is likely to suffer, especially in areas with relati vely limited resources (Sherbinin et al. , 2006).

7. Effects on vulnerable populations (see Chapter 1 ). Where climate change stresses settlements, it is likely to be especially problematic for vulnerable parts of the population: the poor, the elderly, those alr eady in poor health, the disabled, those living alone, those with li mited rights and power ( e.g., recent in-migrants with limited English skills), and/or indigenous populations dependent on one or a few resources. As one example, warmer temperatures in urban summers have a more direct impact on populations who liv e and work without air-conditioning. Implications for environmental justice ar e clear; see, for in stance, Congressional Black Caucus Foundation, 2004.

3-6SAP 4.6 Chapter 3: Human Settlements

8. Effects on vulnerable regions. Approximately half of the U.S. population, 160 million people, will live in one of 673 coastal counties by 2008 (Crossett et al

., 2004). Obviously, settlements in coastal areas – particularly on gently-sloping
coasts –should be concerned about sea leve l rise in the longer term, especially if they are subject to severe storms and st orm surges and/or if their regions are showing gradual land subsidence (Neumann et al. , 2000; Kirshen et al. , 2004). Settlements in risk-prone regions have reason to be concerned about severe weather events, ranging from severe stor ms combined with sea-level rise in
coastal areas to increased risks of fire in drier arid areas. Vulnerabilities may be especially great for rapidly-growing and/ or larger metropolitan areas, where the potential magnitude of both impacts and coping requirements could be very large (IPCC, 2001b; Wilbanks et al

., 2007b).

Different combinations of circumstances are lik ely to cause particular concerns for cities
and towns in the United States as the y consid er possible implications of climate change.

3.2.3. The Interaction of Climate Impacts with Non-Climate Factors.
In general, climate change effects on human settlements in the United States are imbedded in a variety of complexities that make projections of quantitative impacts over long periods of time very difficult. For in stance, looking out over a period of many decades, it seems likely that other kinds of change—such as technological, economic, and institutional—will have more impact on the sust ainability of most settlements rather than climate change per se (Wilbanks, et al

., 2007b). Climate change will interact with other processes, driving forces, and stresses; and its significance, positive or negative, will largely be determined by these interactions. Itis therefore difficult to assess effects of climate change without a reasonably clear pi cture of future scenarios for these other

processes.

In many cases, these interactions involve not only direct im pacts such as warming or more or less precipitation but , sometimes more important, second, third, or higher-order impacts, as direct impacts cascade th rough urban systems and other settlementdetermined processes ( e.g., warming which affects urba n air pollution which affects health which affects public service requireme nts which affect social harmony: Kirshen et al ., 2007). Some of these higher-order impacts, in turn, may feed back to create ripple effects of their own. For example, a heat wa ve may trigger increased energy demands for cooling, which may cause more air conditioners and power generators to be operated, which could lead to higher urban heat island effects, induci ng even higher cooling needs.

Besides this “multi-stress” perspective, it is hi ghly like ly that effects of climate change on settlements are shaped by certain “thresholds,” below which effects are incidental but beyond where effects quickly become major when a limiting or inflection point is reached. An example might be a city’s capac ity to cope with sustained heat stress
combined with a natural disast er. In general, these climate-related thresholds for human
settlements in the United States are not we ll-understood. For multi-stress assessments of thresholds, changes in climate extremes are very often of more concern than changes in climate averages . Besides extreme weather events, such as hurricanes or tornadoes, ice

3-7SAP 4.6 Chapter 3: Human Settlements

storms, winds, heat waves, drought, or fire, settlements may be affected by changes in daily or seasonal high or low levels of te mperature or precipitation, which have not always been projected by climate change models.

Finally, human settlements may be affected by climate change mitigation initiatives as well as by climate change itself. Examples in clude effects on policies related to energy sources and uses, environmental emissions, and land use. The most di rect and short-term effects would likely be on settlements in re gions whose economies ar e closely related to the production and consumption of large quantities of fossil fuels. Indirect and longer term effects are less predictable.

As climate change affects settlements in th e United States, impacts are realized at the
intersection of clim ate change with underlying forces. Most of the possible effects are linked with changes in regional comparative advantage, with consequent migration of population and economic activities (Ruth and Coelho, in press). Examples of these complex interactions and issues include:

1. Regional risks and availability of insurance . It is possible that regions exposed to
risks from clim ate change will see move ment of population and economic activity to other locations. One reason is public pe rceptions of risk, but a more powerful driving force may be the availability of in surance. The insurance sector is one of the most adaptable of all economic sectors, and its exposure to costs from severe
storms and other extreme weather events is likely to lead it to withdraw (or to make much more expensive) private insura nce coverage from ar eas vulnerable to climate change impacts (Wilbanks, et al

., 2007b), which would encourage both
businesses and individual ci tizens to consider other lo cations over a period of
several decades.

2. Areas whose economies are linked with c limate-sensitive resources or assets.
Settlements whose econom ic bases are rela ted to such sectors as agriculture, forestry, tourism, water availability, or other climate-related activities could be affected either positively or negatively by climate change, depending partly on the adaptability of those sectors ( i.e., their ability to adapt to changes without shifting to different locations).

3. Shifts in comparative living co s ts, risks, and amenities. Related to a range of possible climate change effects – higher costs for space cooling in warmer areas, higher costs of water availab ility in drier areas, more or less exposure to storm impacts in some areas, and sea level rise – regions of the Unit ed States and their associated settlements are likely to see gradual changes over the long term in their
relative attractiveness for a variety of human activities. One example, although its likelihood is highly uncertain, would be a gradual migration of the “Sun Belt” northward, as retirees and businesses at tracted by environmental amenities find that regions less exposed to very high temperatures and seasonal major storms are more attractive as places to locate.

3-8SAP 4.6 Chapter 3: Human Settlements

4. Changes in regional comparative advantage related to shifts in energy resource

use. If climate mitigation policies result in shifts from coal and other fossil resources toward non-fossil energy sources , or if climate changes affect the prospects of renewable energy sour ces (especially hydropower), regional economies related to the production and/or use of energy from these sources could be affected, along with regi onal economies more closely linked with alternatives. (citation: SAP 4.5)

5. Urban “footprints” on other areas . Resource requireme nts for urban areas involve larger areas than their own bounded territorie s alone. Ecologists have sought to estimate the land area required to supply the consumption of resources and compensate for emissions and other wastes from urban areas ( e.g., Folke et al. , 1997). By possibly affecting settlements, along with their resource capacities for their inputs and destinations of their outputs, climate change could affect the nature, size, and geographic dist ribution of these footprints.

Human settlements are foci for many economic , social, and governme ntal processes, and historical experience has show n that catastrophes in cities ca n have significant economic, financial, and political effects much more broadly. The case which has received the most attention to date is insurance and finance (Wilbanks, et al

., 2007b).

3.2.4 Realizing Opportunities from Clim ate Change in th e United States
Climate change can have positive as well as negative im plications for settlements. Examples of potential positive effects include:

1. Reduced winter weather costs and stresses. Wa rmer temperatures in periods ofthe year that are normally cold are not necessarily undesirable. They reduce coldrelated stresses and costs ( e.g., costs of warming buildings and costs of clearing ice and snow from roads and streets), part icularly for cold-vulnerable populations. They expand opportunities for warme r-weather recreati onal opportunities over larger parts of the year, and they expa nd growing seasons for crops, parks, and gardens.

2. Increased attention to long-term sustainability . On e of the most positive aspects of climate change can be that its capac ity to stimulate a br oader discussion of what sustainability means for settleme nts (Wilbanks, 2003; Ruth, 2006). Even if climate change itself may not be the mo st serious threat to sustainability, considering climate change impacts in a multi-change, multi-stage context can encourage and facilitate pr ocesses that lead to progr ess in dealing with other
sources of stress as well.

3. Improved competitivenes s compared with settlements subject to more serious adverse impacts. While some settlements may turn out to be “losers” due to climate change impacts, others may be “winners,” as changes in temperature or precipitation result in added economic oppor tunities (see the following section), at least if climate change is not severe. In addition for many settlements climate

3-9SAP 4.6 Chapter 3: Human Settlements

change can be an opportunity not only to compare their net impacts with others, seeking advantages as a result, but to present a progressive image by taking climate change (and related sust ainability issues) seriously.

3.2.5 Examples of Impacts on Metrop olitan Areas in the United States
Possible impacts of clim ate change on sett lements in th e United States are usually assessed by projecting climate changes at a re gional scale: temper ature, precipitation, severe weather events, and sea level rise (see Table 3.2 and Boxes 3.2 and 3.3). Ideally, these regional projections are at a relatively detailed scale, and ideally they consider
seasonal as well as annual cha nges and changes in extremes as well as in averages; but these conditions cannot always be met.

The most comprehensive assessments of possi ble climate chan ge impacts on settlements in the United States have been two studies of major metropolitan areas:

1. New York: This assessment concluded that im pacts of climate change on this metropolitan area are likely to be primar ily negative over the long term, with potentially significant costs increasing as the magnitude of climate change increases, although there are substantial uncertainties. (Rosen zweig and Solecki, 2001a; Rosenzweig and Solecki, 2001b; Solecki and Rosenzweig, 2006).

2. Boston: This assessment concluded that l ong-term i mpacts of climate change are likely to depend at least as much on be havioral and policy changes over this period as on temperature and ot her climate changes (Kirshen et al. , 2004;
Kirshen et al. , 2006; Kirshen et al. , 2007)

Other U.S. studies include Seattle (Hoo a nd Sumitani, 2005) and Los Angeles (Koteen et al. , 2001) (Table 3.1). Internationally, studies have included several m ajor metropolitan areas, such as London (London Climate Change Partnership, 2004) and Mexico City (Molina et al. , 2005) as well as possible impacts on smaller settlements ( e.g., AIACC: see www.aiaccproject.org). A rele vant historical study of effects of an urban heat wave in the United States is reported by Klinenberg (2003).



### 3.3 Opportunities for Adaptati on of Human Settlements to Climate Change

Settlements are important in considering pros pects for adaptation to climate change, both because they represent concentrations of people and because buildings and other infrastructures offer ways to manage risk and monitor/control threats associated with
climate extremes and other non-climate stressors.

Where climate change presents risks of adverse impacts for U.S. settlements and their populations, there are two basic op tions to respond to such con cerns (a third is combining the two). One response is to contribute to clim ate change mitigation strategies, i.e., by taking actions to reduce their greenhouse gas emissions a nd by showing leadership in encouraging others to support such actions (s ee Box 3.5: Roles of Se ttlements in Climate

3-10SAP 4.6 Chapter 3: Human Settlements

Change Mitigation). The second respons e is to consider strategies for adaptation

, i.e., finding ways either to reduce sensitivity to projected changes or to increase the settlement’s coping capacities. Adaptation ca n rely mainly on anticipatory actions to avoid damages and costs, such as “hardening ” coastal structures to sea-level rise; or adaptation can rely mainly on response potentia ls, such as emergency preparedness; or it can include a mix of the two approaches. Res earch to date suggests that anticipatory adaptation may be more cost-effectiv e than reactive ad aptation (Kirshen et al. , 2004).

Adaptation strategies will be important to th e well-being of U.S. settlements as clim ate change evolves over the next cen tury. As just one example, the New York climate impact assessment (Rosenzweig and Solecki, 2001a) proj ects significant increas es in heat-related deaths based on historical relationships be tween heat stress and mortality, unchanged by adaptation. The Boston CLIMB assessment (Kirshen et al. , 2004) projects that, despite similar projections of warming, heat-related deaths will decline over the coming century because of adaptation. Whether or not adaptation to climate change occurs in U.S. cities is therefore a potentially serious issue. The CLIMB assessment includes analyses showing that in many cases adaptation actio ns taken now are better than adaptation actions delayed until a later time (Kirshen et al. , 2006).

3.3.1. Perspectives on Adaptation by Settlements
For decision-makers in U.S. settlements climate change is yet one more source of possible risks that need to be addressed. Climat e change is different as an issue because it is relatively long-term in its implicati ons, future impacts are uncertain, and public awareness is growing from a relatively low level to a higher level of concern. Because climate change is different in these ways, it is seldom attractive to consider allocating massive amounts of funding or management atte ntion to current climate change actions. What generally makes more sense is to consider ways that actions which reduce vulnerabilities to climate change impacts (o r increase prospects for realizing benefits from climate change impacts) are also desira ble for other reasons as well: often referred to as “co-benefits.” Examples include acti ons that reduce vulnerabilities to current climate variability regardless of long-term c limate change, actions that add resilience to water supply and other urban infrastructures th at are already stressed, and actions that make metropolitan areas more attractive for th eir citizens in terms of their overall quality
of life.

Cities and towns have used both “hard” appro aches such as d eveloping infrastructure and “soft” approaches such as re gulations to address impacts of climate variability. Examples include water supply and waste water sy stems, drainage networks, buildings, transportation systems, land use and zoni ng controls, water quality standards and emission caps, and tax incentives. All of thes e are designed in part with climate and environmental conditions in mind. The setting of regulations has always been a context of benefit-cost analysis and political realities; and infrastructure is also designed in a benefit-cost framework, subject to local design codes. The f act that both regulations and infrastructures vary considerably across the United States reflects cultural, economic, and environmental factors; and this suggests that mechanisms ex ist to respond to concerns about climate change. Urban designers and ma nagers deal routinely with uncertainties,

3-11SAP 4.6 Chapter 3: Human Settlements

because they must consider uncertain dem ographic and other socioeconomic changes; thus, if climate change is properly institutiona lized into the urban planning process, it can be handled as yet another uncertainty.

3.3.2 Major Categories of Adaptation Strategies
Adaptation strategies for human settlements, large and small, include a wide range of possibilities such as:

1. Changing the location of people or activit ies (within or between settlements)

– especially addressing the costs of sust aining built environments in vulnerable

areas: e.g., siting and land use policies and prac tices to shift from more vulnerable areas to less, adding resilience to new c onstruction in vulnerabl e areas, increasedawareness of changing hazards and associated risks, and assistance for the lessadvantaged (including actions by the private insurance s ector as a likely driving force).

2. Changing the spatial fo rm of a settlement – ma naging growth and change over decades without excluding critical functions ( e.g., architectural innovations improving the sustainability of structur es, reducing transportation emissions by reducing the length of journeys to wor k, seeking efficiencies in resource use through integration of func tions, and moving from brow n spaces to green spaces). Among the alternatives rece iving the most attention are encouraging “green buildings” ( e.g., green roofs: Parris, 2007; see Rosenzweig et al. , 2006a; Rosenzweig et al. , 2006b) and increasing “green spaces” within urban areas ( e.g., Bonsignore, 2003).

3. Technological change to reduce sensitivity of physical and linkage infrastructures

– e.g., more efficient and affordable interior climate control, surface materials that reduce heat island effects (Quattrochi et al. , 2000), waste reduction and advanced waste treatment, and better warning sy stems and controls. Physical design changes for long-lived infrastructure may also be appropriate, such as building
water-treatment or storm-water runoff out flow structures based on projected sea
level rather than the historical level.

4. Institutional change to improve adaptive capacity, including assuring effective governance, providing financial me chanisms for increasing resiliency, improving structures for coordinating among multiple jurisdictions, targeting assistance programs for especially impacted se gments of the population, adopting sustainable community development pr actices, and monitoring changes in physical infrastructures at an early stage (Wilbanks et al. , 2007a). Policy instruments include zoning, building and design codes, terms for financing, and early warning systems (Kirshen et al., 2005).

5. “No regrets” or low net cost policy initiatives that add resilience to the settlement and its physical capital – e.g., in coastal areas changing building codes for new

3-12SAP 4.6 Chapter 3: Human Settlements

construction to require coping with projec ted amounts of sea-level rise over the expected lifetimes of the structures.

The choice of strategies from among the opt ions is likely to d e pend on co-benefits in terms of other social, economic, and ecological driving forces; the availability of fiscal and human resources; and political as pects of “who wins” and “who loses.”

3.3.3 Examples of Current Adaptation Strategies
In most cases in the United States, settlements have been more active in climate change mitigation than clim ate change adaptation (s ee Box 3.5), but there are some indications that adaptation is growing as a subject of interest (Sol ecki and Rosenzweig, 2005; Ruth, 2006). Bottom-up grassroots activities curren tly under way in the United States are considerable, and that number appears to be growing. For example, Boston has built a new wastewater treatment plant at least one-h alf meter higher than currently necessary to cope with sea level rise, and in a coastal fl ood protection plan for a site north of Boston the U.S. Corps of Engineers incorporated sea- level rise into their analysis (Easterling et al., 2004). California is consideri ng climate change adaptation st rategies as a part of its more comprehensive attention to climate ch ange policies (Franco, 2005). And, Alaska is already pursuing ways to adapt to permafrost melting and other climate change effects.

Meanwhile, in some cases, settlements are taking actions for other reasons that add
resilience to clim ate change effects. An exam ple is the promotion of water conservation, which is reducing per capita water consump tion in cities that c ould be subject to increased water scarcity (City of New York, 2005).

It seems very likely that local governments w ill play an important role in c limate change responses in the United States Many adaptatio n options must be evaluated at a relatively
local scale in terms of their relative costs and benefits and their relationshi ps with other urban sustainability issues, and local govern ments are important as guardians of publicservices, able to mobilize a wide range of stakeholders to contribute to broad communitybased initiatives (as in the case of the London Climate Change Partnership, 2004). Because climate change impact concerns and adaptation potentials tend to cross jurisdictional boundaries in highly fragmente d metropolitan areas, local actions might encourage cross-boundary interactions that w ould have value for other reasons as well.

While no U.S. communities have developed comprehensive programs to ameliorate the effects of heat islands, s ome localities are r ecognizing the need to address these effects. In Chicago, for example, several munici pal buildings have been designed to accommodate “green” rooftops. Atlanta has ha d a Cool Communities “grass roots” effort
to educate local and state officials and deve lopers on strategies th at can be used to mitigate the UHI. This Cool Communities effort was instrumental in getting the State of Georgia to adopt the first commercial build ing code in the co untry emphasizing the benefits of cool roofing technology (Young, 2002; Estes, Jr. et al. , 2003). The “Excessive Heat Events Guidebook” developed by th e Environmental Protection Agency in collaboration with NOAA, CDC, and DHS pr ovides information for municipal officials

3-13SAP 4.6 Chapter 3: Human Settlements

in the event of an excessive heat event: http://www.epa.gov/hiri/about/heatguidebook.html

.
3.3.4: Strategies to Enhance Adaptive Capacity

In most cases, the likelihood of effectiv e adaptation is related to the capacity to adapt,
which in turn is related to such variables as knowledge and awareness, access to fiscal and human resources, and good governance (IPCC, 2001b). Strategies for enhancing such capacities in U.S. settlements are likely to include the development and use of local expertise on climate change issues (AAG, 2003), attention to the emerging experience with climate change effects and response strategies globally and in other U.S. settlements, information sharing about adaptation potentials and constraints among settlements and their components (likely ai ded by modern information technology), and an emphasis on participatory decision-maki ng, where local industries, institutions, and community groups are drawn into di scussions of possible responses.



### 3.4. Conclusions

Even from a current knowledge base that is very limited, it is possible to conclude several things about effects of climate change on human settlements in the United States:

1. Climate change takes place in the context of a variety of factors driv ing an area’s development: it is likely to be a seco ndary factor in most places, with its importance determined mainly by its interac tions with other factors, except in the case of major abrupt climate change (very likely).

2. Effects of climate change will va ry c onsiderably according to location-specific vulnerabilities, and the most vulnerable ar eas are likely to be Alaska, coastal and river basins susceptible to flooding, arid areas where wa ter scarcity is a pressing issue, and areas whose economic bases are climate-sensitiv e (very likely).

3. The main impact concerns, in areas other than Alaska, have to do with changes in the intensity, frequency, a nd/or location of extreme w eather events and, in som e cases, water availability rather than changes in temperature (very likely).

4. Over the time period covered by current cl imate change projections, the potential for adaptation through technological and institutional develo pm ent as well as behavioral changes are considerable, esp ecially where such developments meet other sustainable development needs as well, especially considering the initiatives already being shown at the local level across the United States (extremely likely).

5. While uncertainties are very large about specific impacts in specific time periods, it is possible to talk w ith a higher level of conf idence about vulnerabilities to impacts for most settlements in most parts of the United States (virtually certain).

3-14SAP 4.6 Chapter 3: Human Settlements



### 3.5 Expanding the Knowledge Base

A number of sources, in cluding NACC, 1998; Parson et al. , 2003; Ruth, 2006; and Ruth et al., 2004, have considered research path ways for improving the understanding of effects of climate change on human settlements in the United States. The following list suggests a number of resear ch topics that would help expand the knowledge base about the linkages between clim ate change and human settlements.

 Advance understanding of settlem ent vul nerabilities, impacts, and adaptive responses in a variety of different loca l contexts around the country through case
studies. In addition to identif ying vulnerable settlements, these studies should also identify vulnerable populations (such as the urban poor and native populations on rural and/or tribal lands) that have limited capacities for response to climate change, within those settlements. Better understanding of climate change at the community scale would provide a basis fo r adaptation research that addresses social justice and environm ental equity concerns.

 Develop better projections of climate ch ange at the scale of U.S. m etropolitan areas or smaller, including scenarios pr ojecting extremes and scenarios involving abrupt changes.

 Improve abilities to associate projections of climate change in U.S. settlements with changes in other driving forces re lated to impacts, such as changes in metropolitan/urban patterns and technological change.

 Design practically implem entable, social ly acceptable strategies for shifting human populations and activities away from vulnerable locations.

 Improve the understanding of vulnerabiliti es of urban inflows and outflows to
clim ate change impacts, as well as se cond and third-order impacts of climate change in urban environments, includi ng interaction effects among different aspects of the urban system.

 Improve the understanding of the relations hips between settlem ent patterns (both regional and intra-urban) a nd resilience/adaptive capacity.

 Improve understanding of how urban deci sion-m aking is changing as populations become more heterogeneous and decisions become more decentralized, especially as this affects adaptive responses.

 Review current policies and pr actices related to climate change responses to help
inform community decision-makers and ot her stakeholders about potentials for relatively small changes to make a large difference.

 Evaluate and document experiences with urban/settlement climate change responses while involving decision- making, research and stakeholder communities more actively in discussions of climate change impacts and response

3-15SAP 4.6 Chapter 3: Human Settlements

issues. Focus attention on the costs, bene fits, and possible limits and potentials of adaptation to climate change vulnerabilities in U.S. cities and smaller settlements.

 Improve tools and approaches for infras tructure planning a nd design to reduce exposure and sensitivity to clim ate cha nge effects while increasing adaptive capacity.

 Enhance coordination within federa l governm ent agencies to improve understanding about impacts, vulnerabilities and responses to climate change for
the nation’s cities and smaller settlement s. Connections with U.S. urban decisionmakers can enable integration of climate change considerations into what they do with building codes, zoni ng, lending practices, etc. as mainstreamed urban decision processes.

3-16SAP 4.6 Chapter 3: Human Settlements



### 3.6 References

Amato

, A., M. Ruth, P. Kirshen, and J. Horwitz, 2005: Regional energy demand responses to climate change: methodology and application to the Commonwealth
of Massachusetts. Climatic Change, 71(1) , 175-201.

ACIA , 2004: Impacts of a Warming Arctic: Ar ctic Climate Impact Assessment . Arctic
Climate Im pact Assessment, Cambridge University Press, Cambridge.

AIACC

, As sessments of Impacts and Adaptations to Climate Change in Multiple Regions
and Sectors . Retrieved January 25, 2007, from http://www.aiaccproject.org

Association of American Geographers (AAG) , 2003: Global Change In Local Places: Estimating, Understanding, And Reducing Greenhouse Gases [GCLP Research Team: Kates, R., T. W ilbanks, and R. Ab ler (eds.)]. Association of American Geographers, Cambridge University Press, Cambridge, Massachusetts.

Betsill , M.M., 2001: Mitigating climate change in US cities : Opportunities and obstacles. Local Environment, 4

, 393-406.

Bloomfield , J., M. Smit h, and N. Thompson, 1999: Hot Nights in the City: Global Warming, Sea-Level Rise and the New York Metropolitan Region. Environmental Defense Fund, Washington, DC.

Bonsignure , R., 2003: Urban Green Space: Effects on Water and Climate

, Center for Am erican Urban Landscape, Design Brief Number 3, University of
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Brazel , A.J. and D.A. Quattrochi, 2005: Urban climates. In: En cyclopedia of World Climatology. [J.E. Oliver, (ed.)]. Springer, Dordrecht, The Netherlands, pp. 766-
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Bulkeley

, H. and M. Betsill, 2003 : Cities and Climate Change; Urban Sustainability and
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City of New York , 2005: New York City's Water Supply System. The City of New York Departme nt of Environmental Protection, New York.

Clark , W.C., et al. , 2000: Assessing Vulnerability to Global Environmental Risks

. Discussion Paper 200-12, Environment a nd Natural Resources Program, Kennedy School of Government, Harvard University, Cambridge, Massachusetts.

Colten , C.E., 2005. An Unnatural Metropolis: Wrestling New Orleans from Nature.
Louisiana St ate University, Baton Rouge, Louisiana.

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Congressional Black Caucus Foundation , 2004: African Americans and Climate Change: An Unequal Burden . Redefining Progress, Wa shington, DC.

Crossett , K. M., T. J. Culliton, P.C. Wiley, and T.R. Goodspeed, 2004: Population trends along the coastal United States: 1980- 2008. NOAA National Ocean Service, Management and Budget Office, 54 pp.

Decker , E., S. Elliot, F. Smith, D. Blake, and F. Rowland, 2000: Energy and m aterial flow through the urban ecosystem. Annual Review of Energy and the Environment, 25 , 685-740.

Easterling , W.E., B.H. Hurd, and J.B. Smith, 2004: Coping with Global Climate Change: The Role of Adaptation in the United States , prep ared for the Pew Center on Global Climate Change

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Emanuel , K.A., 2005: Increasing destructiveness of tropical cyclones over the past 30

years . Nature, 436 , 686-688.

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, Jr., M.D., D. Quattrochi, and E. Stasiak, 2003: The urban heat island phenomena:
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Haites , E., K. Caldeira, P. Rome ro Lankao, A. Rose, and T. Wilbanks, 2007: What are the options that could significan tly affect the carbon cycle? In: State of the Carbon Cycle Report (SOCCR) . A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research [Karl, T.R., S. Hassol, C.D. Miller, and W.L. Murray (e ds.)]. National Oceanic and Atmospheric
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Hartwig , R., 2006: Hurricane Season Of 2005, Impacts On U.S. P/C Markets, 2006 And Beyond. Presentation to the Insurance Info rmation Institute, March 2006, New
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Hoo

, W. and M. Sumitani, 2005: Climate Change Will Impact th e Seattle Department of Transportation. Office of the City Auditor, Seattle, Washington, USA

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Hunter , J.R., 2006: Testimony before the Committee on Banking, Housing and Urban
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ICLEI , 2006: ICLEI Local Governments for Sustainability . Retrieved May 28, 2008,
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IPCC

, 2001c: Insurance and other fina ncial services. In: IPCC, 2001b.

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Kirshen , P., 2002: Potential impacts of globa l warm ing in eastern Massachusetts. Journal of Water Resources Planning and Management

, 128(3) , 216-226.

Kirshen , P., M. Ruth, W. Anderson, T. R. Lakshm anan, S. Chapra, W. Chudyk, L. Edgers, D. Gute, M. Sanayei, and R. Vogel, 2004: Climate's Long-term Impacts

on Metro Boston . Final Report to the U.S. E nvironmental Protection Agency,
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Kirshen , P., M. Ruth and W. Anderson. 2005: Clim ate change in metropolitan Boston, New England Journal of Public Policy

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Kirshen , P., M. Ruth, and W. Anderson, 2006: Clim ate’s long-term impacts on urban
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Kirshen , P., M. Ruth, and W. Anderson, 2007: Interdependencies of urban clim ate change impacts and adaptation strategi es: a case study of metropolitan Boston. Climatic Change

, 66 , 105-122.

Klinenberg , E., 2003: Heat Wave: A Social Autopsy of Disaster in Chicago . University of Chicago, Chicago, Illinois.

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Koteen , L., J. Bloomfield, T. Eichler, C. Tonne , R. Young, H. Poulshock, and A. Sosler,
2001: Hot Prospects: The Potential Impacts of Global Warming on Los Angeles
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Molina

, M., et al. , 2005: Air Quality in the Mexico Megacit y: An Integrated Assessment. Kluwer, Dordrecht, Netherlands.

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NACC

, 1998: Climate Change and a Global City: An Assessment of the Metropolitan East Coast Region. Columbia Earth Institute/NASA Goddard Institute for Space
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Neumann , J.E., G. Yohe, R. Nichols, and M. Manion, 2000: Sea Level Rise and Global Climate Change: A Review of Impacts to U.S. Coasts . Pew Center on Global Climate Change, Washington, DC.

NRC , 2007: Evaluating Progress of the U.S. Clim ate Change Science Program: Methods and Preliminary Results . Comm ittee on Strategic Advice on the U.S. Climate Change Science Program, National Academies Press, Washington, DC.

Parris

, T., 2007: Green buildings. Environment

, 49(1) , 3.

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, 2003: Understanding climatic impacts, vulnerabi lities, and adaptation in the United States: building a capac ity for assessment, Climatic Change, 57(1-2) , 9–42.

Patz , J.A. and J.M. Balbus, 2001: Global climate change and air pollution. In: Ecosystem Change and Public Health. A Global Perspective [Aron J.L. and J.A. Patz (eds.)]. The Johns Hopkins Univ ersity Press, Baltimore, pp. 379–408.

Quattrochi , D.A., J.C. Luvall, D.L. Rickma n, M.G. Estes, Jr., C.A. Laymon, and B.F. Howell, 2000: A decision support system for urban landscape management using
thermal infrared data. Photogrammetric Engineering and Remote Sensing, 66

, 1195-1207.

Rabe , B., 2006: Second Generation Climate Policies in the States . Paper presented at the Conference Climate Change Politics in North America, Washington, DC, 18-19.

Ridd

, M.K., 2006: 10.3 Environmental dynamics of human settlements. In: Remote Sensing of Human Settlements, Man ual of Remote Sensing, Third Edition, Volume
5 [Ridd, M.K. and J.D. Ripple, (eds.)]. American Society for Photogrammetry and Remote Sensing, Bethesda, Maryland, pp. 564-642.

Riebsame , W., 1997: Atlas of the New West: Portrait of a Changing Region. W. W. Morton, New York.

Romero Lankao , P., 2007: Are we mi ssing the point? Particularities of urbanization, sustainability and carbon emissions in Latin American cities. Urbanization and Environment, 19(1)

.

Rosenzweig , C., W. Sol ecki, C. Paine, V. Gornitz, E. Hartig, K. Jacob, D. Major, P. Kinney, D. Hill, and R. Zimmerman, 2000: Climate Change and a Global City: An Assessment of the Metropolitan East Coast Region . U.S. Global Change Research Program.

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Rosenzweig , C., and W. Solecki (eds.), 2001a: Climate Change and a Global City: The Potential Consequences of Climate Vari ability and Change – Metro East Coast

. Columbia Earth Institute, New York.

Rosenzweig

, C. and W.D. Solecki, 2001b: Global environmental change and a global city: lessons for New York. Environment, 43(3) , 8-18.

Rosenzweig

, C., S. Gaffin, and I. Parshall (eds.), 2006a: Green Roofs In The New York Metropolitan Region . Research Report, Columbia University Center for Climate Systems Research and NASA Goddard Institute for Space Studies, New York.

Rosenzweig , C., W. Sol ecki, and R. Slosberg, 2006b: Mitigating New York City’s Heat Island with Urban Forestry, Living Roofs, and Light Surfaces . Final Report, New York City Regional Heat Island Initiative, Prepared for the New York State Energy Research and Development Au thority, NYSERDA Contract #6681, New
York.

Rosenzweig , C., W. Sol ecki, L. Parshall, M. Chopping, G. Pope, and R. Goldberg, 2005: Characterizing the urba n heat island in current and future climates in New Jersey, Global Environmental Change Part B: Environmental Hazards

, (6) , 51-62.

Ruth

, M. (ed.), 2006: Smart Growth and Climate Change . Edward Elgar Publishers, Cheltenham, England, 403 pp.

Ruth , M., A. Amato, and P. Kirshen, 2006a: Im pacts of changing temperatures on heatrelated mortality in urban areas: the issues and a case study from metropolitan

Boston. In: Smart Growth and Climate Change [Ruth, M. (ed.)]. Edward Elgar Publishers, Cheltenham, England, pp. 364 – 392.

Ruth

, M., K. Donaghy, and P.H. Kirshen (eds.), 2006b: Regional Climate Change and Variability: Impacts and Responses . Edward Elgar Publishers, Cheltenham, England, 260 pp.

Ruth , M. and A-C Lin, 2006c: Regional energy and adaptations to climate change:

m ethodology and application to the state of Maryland, Energy Policy

, 34 , 2820-
2833.

Ruth

, M., C. Bernier, N. Jollands, and N. Gol ubiewski, 2007: Adaptation to urban water supply infrastructure to impacts from c limate and socioeconomic changes: the case of Hamilton, New Zealand. Water Resources Management

, 21 , 1031-1045.

Ruth , M. and D. Coelho. In press: Ma naging the interrela tions among urban infrastructure, population, and institutions. Global Environm ental Change.

3-22SAP 4.6 Chapter 3: Human Settlements

Selin , H. and S.D. VanDeveer, 2006: Political science and prediction: What’s next for U.S. climate change policy? Review of Policy Research (forthcoming).

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climate hazards. Environment and Urbanization, 12(2)

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, W.D. and C. Rosenzweig, 2006: Climate ch ange and the city: observations from metropolitan New York. In: Cities and Environmental Change , [Bai, X. (ed.)]. Yale University Press, New York.

Solecki , W. and R. Leichenko, 2006: Urbanizati on and the m etropolitan environment. Environment, 48(4) , 8-23.

Steinberg , T., 2006. Acts of God: The Unnatural Histor y of Natural Disaster in America. Oxford, Ne w York.

Stone , B., 2006: Physical planning and ur ban heat island formation, 2006. In: Smart Growth and Climate Change [Ruth, M. (ed.)]. Edward Elgar Publishers,
Cheltenham , England, pp. 318-341.

Vale , L.J., and T J. Campanella, 2005. The Resilient City: How Modern Cities Recover from Disaster, Oxford, New York.

Wilbanks , T.J., 2003: Integrating climate change and sustainable developm ent in a place-based context. Climate Policy . Supplement on Climate Change and Sustainable Development, 3(1) , 147-154.

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Young , B., 2002: Thinking clean and green. Georgia Trend, 18 , 93-100.

3-23SAP 4.6 Chapter 3: Human Settlements



### 3.7 Boxes

Box 3.1: U.S. Urban Responses to Environmental Change: A Historial Perspective

Over time, American cities have been affected by en vironmental change. City founders often showed an important disregard with respect to siting of settle ments, focusing on aspects of location such as commercial or recreational opportunities rather than on ri sks such as flood potential, limited water, food or fuel supplies, or the presence of health threats. Ofte ntimes settlers severely exploited their environments, polluting ground water and adjacent water bodies, bu ilding in unsafe and fragile locations, changing landforms, and filling in wetlands. Construction of the urban built environment involved vast alterations in the landscape, as forests and vegetation and wildlife species were eliminated and replaced by highways, suburbs, and commercial buildings. The building of wastew ater and water supply sy stems had the effect of altering regional hydrology and creating large vulnerab ilities. In other cases settlers concluded that the weather was changing for the good, that technology would solve problems or that new resources could be
discovered.

Technological fixes were pursued to seek ways to modify or control environmental change. Cities exposed to flooding built levees and seawalls and channelized rivers. When urbanites depleted and polluted local water supplies cities went outside their boundaries to seek new supplies: building reservoirs, aqueducts, and creating protected watersheds. When urban consumption exhausted local fuel sources, cities adapted to new fuels, embraced new technologies, or searched far beyond c ity boundaries for new supplies. Many of these actions resulted in the extension of the urban ecological footprint, so that urban growth and development affected not only the urban site but also increasingly the urban hinterland and beyond.

There are few examples of environmental disasters or climate change actually resulting in the abandonment of an urban site. One case appears to be that of th e Hohokam Indians of the Southwest, who built extensive irrigation systems, farmed land, and built large and dense settlements over a period of approximately 1,500 years (Krech, 1999: 45-72). Yet, they abandoned thei r settlements and disappeared into history. The most prominent explanation for their disa ppearance is an ecological one -- that the Hohokam irrigation systems suffered from salinization and water logging, eventually making them unusable. Other factors besides ecological ones may have also entered into the demise of their civilization and abandonment of their cities, but the ecological explanation appear s to have the most supporters.

In the case of America in the 19th and 20th centuries, however, no city has been abandoned because of environmental or climatic factors. Galveston, Texas su ffered from a catastrophic tidal wave but still exists as a human settlement, now protected by an extensive sea wall. Johnstown, Pennsylvania has undergone major and destructive flooding since the late 19th century, but continues to survive as a small city. Los Angeles and San Francisco are extremely vulnerable to earthquakes, but still continue to increase in population. And, in coming years New Orleans almost certainly will experience a hurricane as or more severe than Katrina, and yet rebuilding goes on, enc ouraged by the belief that technology will protect it in the future. Whether or not ecologi cal disaster or extreme risk will eventually convince Americans to abandon some of their settlements, as the Hohokam did, has yet to be determined (Colten, 2005; Steinberg, 2006; Vale and Campanella, 2005).

3-24SAP 4.6 Chapter 3: Human Settlements

Box 3.2: Vignettes of Vulnerability - I

Alaskan Settlements No other region in the United States is likely to be as profoundly changed by climate change as Alaska, our nation’s part of the polar region of Earth (ACIA, 2004). Because warming is more pronounced closer to the poles, and because settlement and econom ic activities in Alaska have been shaped and often constrained by Arctic conditions, in this region warming is especially likely to reshape patterns of human
settlement. Human settlements in Alaska are already being exposed to impacts from global warming (ACIA, 2004), and these impacts are expect ed to increase. Many coastal communities see increasing exposure to storms, with significant coastal erosion, and in some cas es facilities are being forced either to relocate or to face increasing risks and co sts. Thawing ground is beginning to de stabilize transportatio n, buildings, and other facilities, posing needs for rebuilding, with ongo ing warming adding to construction and maintenance costs. And indigenous communities are facing major ec onomic and cultural impacts. One recent estimate of the value of Alaska’s public infrastructure at risk from climate change set the value at tens of billions of today’s dollars by 2080, with the re placement of buildings, bridges, and ot her structures with long lifetimes having the largest public costs (Larsen et al. , 2007). Besides impacts on built infrastructures designed for permafrost foundations and effects on indigenous societies, many observers expect warming in Alaska to stimulate more active oil and gas development (and perhaps other natural resource exploitation), and if thawing of Arctic ice permits the opening of a year-round Northwest sea passage it is virt ually certain that Alaska’s coast will see a boom in settlements and port facilities (ACIA, 2004).

Coastal Southeast Settlements While there is currently no evidence for a long-t erm increase in North Am erican mainland landfalling hurricanes, concerns remain th at certain aspects of hurricanes, su ch as wind speed and rainfall rates may increase (CCSP, 2008). In addition, sea level rise is expected to increase storm surge levels (CCSP, 2008). Recent hurricanes striking the coast of the U.S. Southeast cannot be attributed clearly to climate change, but they suggest a range of possible impacts. As an extreme case, consider the example of Hurricane Katrina. In 2005, the city of New Orleans had a population of about half a million, located on the delta of the Mississippi River along the U.S. Gulf Coast. Urban development throughout the 20 th Century has significantly increased land use and settlement in ar eas vulnerable to flooding, and a number of studies had indicated growing vulnerabilities to storms and fl ooding. In late August 2005, Hurricane Katrina moved onto the Louisiana and Mississipp i coast with a storm surge, suppleme nted by waves, reaching up to 8.5 m above sea level. In New Orleans, the surge reached around 5m, overtopp ing and breaching sections of the city’s 4.5m defenses, flooding 70 to 80 % of New Orleans, with 55 % of the city’s properties inundated by more than 1.2 m and maximum flood depths up to 6 m. 1101 people died in Louisiana, nearly all related to flooding, concentrated among the poor an d elderly. Across the whole region, there were 1.75 million private insurance claims, costing in excess of $40 billion (Hartwig, 2006), while total economic costs are projected to be significantly in excess of $ 100 billion. Katrina also exhausted the federally backed National Flood Insurance Program (Hunter, 2006), whic h had to borrow $20.8 billion from the Government to fund the Katrina residential flood claims. In New Orleans alone, while flooding of residential structures caused $8-$10 billion in losses, $3-6 billion was uninsur ed. 34,000-35,000 of the flooded homes carried no flood insurance, including many that were not in a designated flood risk zone (Hartwig, 2006). Six months after Katrina, it was estimated that the population of New Orleans was 155,000, w ith the number projected to rise to 272,000 by September 2008 – 56% of its pre-Katrina level (McCarthy et al ., 2006).

3-25SAP 4.6 Chapter 3: Human Settlements

Box 3.3: Vignettes of Vulnerability – II

Arid Western Settlements

Human settlements in the arid West are affected by climate in a variety of ways, but perhaps most of all by water scarcity and risks of fire. Clearly, access to water for urban populations is sensitive to climate, although the region has developed a vast system of engineered water storag e and transpor t facilities, associated with a very complex set of water rights laws (NACC, 2001). It is very likely that climate change will reduce winter snowfall in the West, reducing tota l runoff – increasing spring runoff while decreasing summer water flows. Meanwhile, water demands for urban populations, agriculture, and power supply are expected to increase, and conflicts over water rights are likely to increase. If total precipitation decreases or becomes more variable, extending the kinds of drought that have affected much of the interior West in recent years, water scarcity will be exacerbated, and increased water withdrawals from wells could affect aquifer levels and pumping costs. Moreover, drying increases risks of fire, which have threatened urban
areas in California and other Western areas in recent years. The five-year averag e of acres burned in the West is more than 5 million, and urban expansion is increasing the length of th e urban-wild lands interface (Morehouse et al. , 2006). Drying would lengthen the fire season, and pest outbreaks such as the pine beetle
could affect the scale of fires.

Summer 2006 Heat Wave

In July and August 2006, a severe heat wave spread acr oss the United States, with most parts of the country recording temperatures well above th e average for that time of the year . For example, temperatures in California were extraordinarily high, setting records as high as 130°. As many as 225 deaths were reported by press sources, many of them in major cities such as New York and Chicago. Electric power transformers failed in several areas, such as St. Louis and Queens , New York, causing interruptions of electric power supply, and some cities reported heat-related damages to water lines and roads. In many cities, citizens without home air-conditioning sought shelter in public and office buildings, and city/county health departments expressed particular concern for the elderly, the young, pregnant women, and individuals in poor health. Although this heat wave cannot be attributed directly to climate change, it suggests a number
of issues for human settlements in the United States as they contemplate a prospect of temperature
extremes in the future that are higher and/or longer-lastin g than historical experience.

3-26SAP 4.6 Chapter 3: Human Settlements

3-27 Box 3.4: Climate Change Impacts on The Urban Heat Island Effect (UHI)
(Lo and Quattrochi, 2003; Brazel and Qua ttrochi, 2006; Ridd, 2006; Stone, 2006)

Climate change impacts on the Urban Heat Island (UHI ) effect will primarily depend upon the geographic location of a specific city, its urban morphology ( i.e., landscape and built-up characteristics), and areal extent ( i.e., overall spatial “footprint”). These factors will mi tigate or exacerbate how the UHI phenomenon (Figure 3.1) is affected by climate change, but overall, climate change is likely to impact the UHI effect in the following ways:

• Exacerbation of the intensity and areal extent of the UHI as a result of warmer surface and air temperatures along with the overall growth of ur ban areas around the world. Additionally, as urban areas grow and expand, there is a propensity for lower albedos which forces a more intense UHI effect. (There is also some indication that sustained or prolonged higher nighttime air temperatures over cities that may result from warmer global temperatures will have a more significant impact on humans than higher daytime temperatures.)

• As the UHI intensifies and increases , there could be a subsequent impact on deterioration of air quality, particularly on ground level ozone caused by higher overall air temperatures and an increased background effect produced by the UHI as an additive air temperature factor that helps to elevate ground level ozone production. Additionally, particulate matter (PM 2.5 ) could increase due to a number of human induced and natural factors ( e.g., more energy production to support higher usage of air conditioning).

• The UHI has an impact on local meteorological conditions by forcing rainfall production either over,

o r downwind, of cities. As the UHI effect intens ifies, there will be a higher probability for urbaninduced rainfall production (dependent upon geographic location) with a subsequent increase in urban runoff and flash flooding.

• Exacerbation a n d intensification of the UH I would have impacts on human health:

- increase d incidence of heat stress

- i mpact on respiratory illnesses such as asthma due to increases in particulate matter

cau sed by deterioration in air quality as we ll as increased pollination production because of earlier pollen production from vegetation in response to warmer overall temperatures

Figure 3.1. Example of urban surface temperatures and albedo for the Atlanta, Georgia Central Business District (CBD) area derived from high spatial reso lution (10m) aircraft thermal remote sensing data.

The image on the left illustrates da ytim e surface heating for urban surf aces across the CBD. White and red colors indicate very warm surfaces (~ 40-50°C). Green relates to surfaces of moderately warm temperatures (~25-30°C). Blue indicates cool su rfaces (e.g., vegetation, shadows) (~ 15-20°C). Surface temperatures are reflected in the albedo image on the right where warm surfaces are dark (i.e., low reflectivity) and cooler surfaces are in red and green (i.e., higher refl ectivity). The images ex emplify how urban surface characteristics influence temperature and albedo as drivers of the urban heat island effect (Quattrochi et al., 2000).SAP 4.6 Chapter 3: Human Settlements

Box 3.5: Roles of Settlements in Climate Change Mitigation

Although U.S. government commitments to climate change mitigation policies at the
national level have emer ged only recently, an increasing number of state and local authorities are involved in strategies to mitigate greenhouse gas emissions (Selin and Vandeveer, 2005; Rabe, 2006; Selin, 2006). U.S. states and cities are join ing such initiatives as ICLEI (ICLEI, 2006), the U.S. Mayor Climate Protection Agreement, the Climate Change Action Plan, the Regional Greenhouse Gas Initiative (RGGI) (Selin, 2006), and the Large Cities Climate Leadership Group. 1 These initiatives focus on emissions inventories; on such actions aimed at reducing GHG emissions as switching to more energy efficient vehicles, using more efficient furnaces and conditioning systems, and introduc ing renewable portfolio standards (RPS). These strategies,
which mandate an increase in the amount of elect ricity generated from renewable resources also adapt to negative social, economic and environmen tal impacts; and on actions to promote public awareness (see references in footnote 1).

Different drivers lie behind these mitigation efforts. Public and private entities have begun to “perceive” such possible impacts of climat e change as rising sea level, extreme shifts in weather, and losses of key resources. They have realized that a reduction of GHG emissions opens opportunities for longer economic development ( e.g., investment in renewable energy: Rabe, 2006). In addition, climate change can become a political priority if it is reframed in terms of local issues ( i.e., air quality, energy conservation) already on the policy agenda (Betsill, 2001; Bulkeley and Betsill, 2003; Romero Lankao, 2007)

The promoters of these initiatives face ch allenges related partly to inertia ( e.g., the time it takes to replace energy facilities and equipment with a relatively long life of 5 to 50 years: Haites
et al.

, 2007). They can also face opposition from organi zations who do not favor actions to reduce GHG emissions, some of whom are prepared to bring legal challenges against state and local initiatives (Rabe, 2006:17). But the number of bottom-up grassroots activities currently under way in the United States is considerable, a nd that number appears to be growing.

1 ICLEI is the International Council for Local Environmental Initiatives. Local governments participating inICLEI’s Cities for Climate Protection (CCP) Campaign commit to a) conduct an energy- and emissionsinventory and forecast, b) establish an emissions ta rget, c) develop and obtain approval for the Local Action Plan, d) Implement policies and measures, and e) monitor and verify results (ICLEI, 2006: April 20
2006 www.iclei.org ). The Large Cities Climate Leadership Group is a group of cities committed to the
reduction of urban carbon emissions and adapting to climate change . It was founded following the World Cities Leadership Climate Change Summit organized by the Mayor of London in October 2005 . For more information on the US Mayor Climate Protection Agreement see http://www.seattle.gov/mayor/climate/

3-28SAP 4.6 Chapter 3: Human Settlements



### 3.8 Tables

Table 3.1. Overview of Integrated Assessments of Climate Impacts and Adaptation in U.S.
Cities. “x” indicates that the referenc e addresses a category of interest.

Bloomfield et al. , 19 99 Koote n et al. , 2001 Rose nzweig et al. , 2000 Kirshen et al. , 2004 Ho o and Sumita n i, 2005

Location: Greater Los
An geles N ew York Metropolitan
New York Metropolitan

Boston Metro politan
Seattle Coverage: Water supply 9 9 9 9 Water Quality 9
Water Demand 9
Sea-level Rise 9 9 9 9 Transportation 9 9
Communication Energy 9 9
Public Health
Vector-borne Diseases
Food-borne Diseases 9 Temperature-related Mortality 9

Temperature-related Morbidity 9 9

Air-quality Related Mortality Air-quality Related Morbidity 9

Other Health Issues 9 9 9 Ecosystems
Wetlands Other Ecol.(Wildfires) 9 9 Urban Forests (Trees and Vegetation) 9

Air Quality 9 9

Extent of: Quantitative Analysis Low Medium Medium High Low Computer-based Modeling None Low Low High None

Scenario Analysis None None Medium High Medium Explicit Risk Analysis None None None Medium None
Involvement of: Local Planning Agencies None None High High High
Local Government Agencies None None High High High

Private Industry None None None Low None Non-profits None None Low High None Citizens None None None Medium None
Identification of: Adaptation Options X X X X X Adaptation Cost X X Extent of Integration Across Systems None None Low Medium Low

Attention to Differential Impacts ( e.g., on individual types of businesses, populations) None None Low Low Low

3-29SAP 4.6 Chapter 3: Human Settlements

Table 3.2. Regional vulnerabilitie s of settlements to impacts of c limate change in the United
States

REGIONAL VULNERABILITIES OF SETTLEMENTS TO
IMPACTS OF CLIMATE CHANGE

Region Vulnerabilities Major Uncertainties

Metro NE Flooding, infrastructures, health, water supply

, sea-level rise Storm behavior, precipitation

Larger NE Changes in local landscapes,
tourism

, water, energy needs Ecosystem impacts

Mid-Atlantic Multiple stresses; e.g., interactions between cli mate change and aging infrastructures Ecosystem impacts

Coastal SE More intense storms, sea-level rise, flooding, heat

stress Storm behavior, coastal land use, sea-level rise

Inland SE Water shortages, heat stress, UH1, economic impacts Precipitation change, development paths

Upper Midwest Lake and river levels, extreme
weather event s , health Precipitation change, storm
behavior

Inner Midwest Extreme weather events, health Storm behavior

Appalachians Ecological change, reduced
dem a nd for coal Ecosystem impacts, energy polic y impacts

Great Plains Water supply, extreme events,
stresses on communities Precipitation changes, weather

e xtrem es

Mountain West Reduced snow, water shortages, fire, tourism Precipitation changes, effects on winter snowpack

Arid Southwest Water shortages, fire Development paths, precipitation changes

California Water shortages, heat stress; sea
level rise Temperature and precipitation changes, infrastructure i m pacts

Northwest Water shortages, ecosystem

stress es, coa stal effects Precipitation changes, sea-level
rise

Alaska Effects of warming, vulnerable populati ons War ming, sea-level rise

Hawaii Storms and other weather

extre m es, freshwater supplies, health, sea-level rise Storm behavior, precipitation change

3-30SAP 4.6 Chapter 3: Human Settlements



### 3.9 Figures

Figure 3.1. Example of urban surface temperatures and albedo for the Atlant a, Georgia Central Business District (CBD) area derived from high spatial resolution (10m) aircraft thermal remote sensing data.

(Quattrochi et al., 2000)

3-31

## Synthesis and Assessment Product 4.6

Chapter 4: Effects of Global Change on Human Welfare

Lead Author : Frances G. Sussman, Environmental Economics Consulting

Contributing Authors: Maureen L

. Cropper, University of Maryland at College Park; Hector Galbraith, Galbraith Environmental Sciences LLC; Da vid Godschalk, University of North Carolina at Chapel Hill; John Loomis, Colorado State University; George Luber, Centers for Disease Control and Prevention; Michael McGeehin, Centers for Disease Control and Prevention; James E. Neumann, Industrial Economics, Incorporated; W. Douglass Sh aw, Texas A&M University; Arnold Vedlitz, Texas A&M University; Sammy Zahran, Colorado State UniversitySAP 4.6 Chapter 4: Human Welfare



### TABLE OF CONTENTS

4.1 Introduction ............................................................................................................... ..............................3

4.2 Human Welfare, Well-being, and Quality of Life............................................................................. ....4

4.2.1 Individual Me asures of Well-being...................................................................................... .............5

4.2.2 The Social Indicators Approach ......................................................................................... ..............6

4.2.3 A Closer Lo ok at Co mmunities........................................................................................... ............10

4.2.4 Vulnerable Populations , Communities, and Adaptation.................................................................12

4.3 An Economic Approa ch to Human Welfare ...................................................................................... .13

4.3.1 Econom ic Valu ation ..................................................................................................... ..................15

4.3.2 Impacts Assessment and Monetary Valuation .............................................................................. ..16

4.3.3 Human Health ................................................................................................................................17

4.3.4 Ecosystems......................................................................................................................................22

4.3.5 Recreational Ac tivities and Op portunities.............................................................................. ........28

4.3.6 Amenity Value of Climate ............................................................................................... ................35

4.4 Conclusions ................................................................................................................ ............................38

4.5 Expanding the Knowledge Base ............................................................................................... ............39

4.6 References ................................................................................................................. .............................41

4.7 Appendix 1 ................................................................................................................. ............................57

4.8 Boxes...................................................................................................................... .................................64

4.9 Tables......................................................................................................................................................66

4.10 Figures ................................................................................................................... ...............................72

4 -2SAP 4.6 Chapter 4: Human Welfare



### 4.1 Introduction

Human welfare is an elusive concept, and th ere is no single, commonly accepted definition or approach to thinking about welfare. Yet there is a shared understanding that human welfare, well-being, and quality of life (terms that are often used in terchangeably) refer to aspects of individual and group life that improve living conditions and reduce chances of injury, stress, and loss. The physical environment is one factor , among many, that may improve or reduce human well-being. Climate is one aspect of the physical environment, and can affect human well-being via economic, physical, psychological, and social pathways that in fluence individual perceptions of quality of life.

Climate change may result in lifestyle change s and adaptive behavior with both positive and negative implications for well-be ing. For example, warm er temperatures may change the amount of time that individuals are comfortable sp ending outdoors in wor k, recreation, or other activities, and temperature combin ed with other climatic change s may alter (or induce) changes in intra- and inter-country human migration patterns. More genera lly, studies of climate change and the United States identify an assortment of impacts on human health, the productivity of human and natural systems, and human settleme nts. Many of these impacts—ranging from changes in livelihoods to changes in water qua lity and supply—are linked to some aspect of human well-being.

Communities are an integral determinant of hum an well-bein g. Climate change that affects public goods—such as damaged infrastructure or interruptions in public services—or disrupts the production of goods and services, will affect economic performance including overall health, poverty, employment, and other measures. These changes may have consequences, such as a lost job or a more difficult commute, that affect individual well-being dire ctly. In other cases, individual well-being may be indirectly affect ed due to concern for the well-being of other individuals, or for a lack of c ohesion within the community. The su stainability or resilience of a community ( i.e., its ability to cope with climate change and other stressors over the long term) may be reduced by climate change weakening the physical and social environment. In the extreme, such changes may undermine the individual ’s sense of security or faith in government’s capacity to accommodate change.

Completely cataloging the effects of global change on huma n well-be ing or welfare would be an immense undertaking. Despite its importance, no well-accepted structure for doing so has been developed and applied. Moreover, little (if any) research focuse s explicitly on the impact of global change on human well-being, per se . The chapter seeks to make a review of this topic manageable by focusing on several discrete issues:

 Alternative approaches to defi ning and studying huma n well-being

 Identifying huma n well-being and quality of lif e measures and indica tors (qualitative and quantitative)

 Describing economic we lfare and monetary methods of assigning value to climate change’s potential impacts

 Providing examples of c limate change impact s on selected categories of well-being and reporting indicators of economic welfare for these categories

4 -3SAP 4.6 Chapter 4: Human Welfare

Section 4.2, focuses on valuation and non-monetary me trics and draws on the literature to provide insights into a possible f oundation for future research into the effects of climate change on human well-being. This section first discusses the literature defining human well-being. Next, it presents an illustrative place-based-indicators approach (the typical approach of planners and policy makers to evaluating quality of life in communities, cities, and countries). Approaches of this type represent a commonly accepted way of th inking about well-being that is linked to objective (and sometimes subjective) measures. Wh ile a place-based indicators approach has not been applied to climate change, it has the pot ential to provide a framework for identifying categories of human well-being th at might be affected by clim ate change, and for making the
identification of measures or metr ics of well-being a more concrete enterprise in the future. To illustrate that potential, the section draws links between community welfare and some of the negative impacts of climate change.

Economics has been at the forefront of efforts to quantify the welfare imp acts of clim ate change. Economists employ, however, a very specific definition of well-being— economic welfare—for valuing goods and services or, in this case, climate impacts. This approach is commonly used to support environmental policy decision making in many areas. Section 4.3 ve ry briefly describes the basis of this approach, and the techniques th at economists use (focusing on those that have been applied to estimate impacts of climate change). This section next summarizes the existing
economic estimates of the non-market impacts of climate change. 1 An accompanying appendix provides more information on the economic appr oach to valuing cha nges in welfare, and highlights some of the challenges in applyi ng valuation techniques to climate impacts.

The fourth section of the chapter summarizes some of the key points of the chapter and the chapter concludes with a brief discussion of research gaps.



### 4.2 Human Welfare, Well-being, and Quality of Life

No single, widely accepted definition exists for th e term human welfare, or for related terms such as well-being and quality of life, and they ar e all often used interchangeably (Veenhoven, 1988, 1996, 2000; Ng, 2003; Rahman, 2007). Academic economists, epidemiologists, health scientists, psychologists, sociologists, geograp hers, political scien tists, and urban planne rs have all rendered
their own definitions and statistical indicators of life quality at both individual and community
levels. 2 For purposes of clarity in this chapter, from this point forward we adopt the convention of the Millenium Assessment (MA, 2005) and th e Intergovernmental Panel on Climate Change (IPCC, 2007b), which use “well-being” as an umbrel la term—referring broadl y to the extent to which human conditions satisfy the range of cons tituents of well-being, in cluding health, social relations, material needs, security, and freedom of choice. “Quality of life” is here used

1 Because more concrete aspects of welfare, such as imp acts on prices or income, may be covered by other synthesis and assessment products (see, for example, di scussions of dollar values in SAP 4.3, The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity, which is in draft form at the time this is being written), this report focuses exclusively on the types of in tangible amenities that directly impact quality of life, but are not traded in markets, including health, recreation, ecosystems, and climate amenities.

2 For example, In sociological literature, the terms well- being and welfare are used interchangeably to refer to objectively measurable life chances and experiences, and the term quality of life is used to describe subjective assessments and experi ences of individuals

.

4 -4SAP 4.6 Chapter 4: Human Welfare

synonymously with well-being, to reflect usage in a wide range of disciplines, including medical, sociological, psychological, and ur ban planning literatures. The term “welfare” is generally used herein to refer narrowly to economic measures of individual well-being, although it is also used
in the context of communities in a broader sense.

Despite differences in definitions, human well-be ing—in its broadest sense—is typ ically a multidimensional concept, addressing the availabilit y, distribution, and possess ion of economic assets, and non-economic goods such as life expectan cy, morbidity and mo rtality, literacy and educational attainment, natural resources and ecosystem services , and participatory democracy. These conceptualizations often also include soci al and community resources (sometimes referred to as social capital in social sc ientific literature), such as the presence of voluntary associations, arts, entertainment, and shared recreational amenities (see Putnam, 1993, 2000). The quantity of community resources shared by a populat ion is often called social capital. 3 These components of life quality are interrelated and correlate with subjectiv e valuations of life satisfaction, happiness, pleasure, and the operation of successful demo cratic political systems (Putnam, 2000).

The concepts of well-being, economic welfare, a nd quality of life play important roles not only in academic research, but also in p ractical anal ysis and policy making. Qu ality of life measures may be used, for example, to gauge progress in meeting policy or normative goals in particular cities by planners; municipaliti es in New Zealand, England, Ca nada, and United States have constructed their own metrics of quality of life to estimate the overall well-being and life chances available to citizens. Similarly, health-related quality of life measures can indicate progress in meeting goals. For example, the U.S. Medicare pr ogram uses metrics to track quality of life for beneficiaries and to monitor and improve h ealth care quality (HCFR, 2004). Moreover, international agencies from the United Nations Human Development Programme (UNDP) to the Milllenium Ecosystem Assessment on Ecosystems and Human Well-Being and highly regarded periodicals like The Economist , have built composite measures of human and societal well-being to compare and rank nations of the world. 4

Life quality and human well-being are increasingly important objec ts of theoretical and empirical research in diverse disciplines. Two analytic a pproaches characterize th e research literature: (1) studies that emphasize well-being as an indivi dual attribute or possessi on; and (2) studies that treat well-being as a social or economic phe nomenon associated with a geographic place.

4.2.1 Individual Measures of Well-being
Approaches focusing on individuals are genera lly found in me dical, health, cognitive, and economic sciences, and it is to these we turn firs t, and then next to place-focused indicators.

3 The concept of social capital has been defined, in different ways, by Putnam (1993, 1995, 2000) and by Coleman (1988, 1990, 1993). For Coleman, social capital is a store of community value that is embodied in social structures and the relations between social actors, from which individuals can draw in the pursuit of private interest. Putnam’s definition is similar, but places a stronger emphasis on altruism and community resources.

4 See, for example, the discussion of the sources of Table 1 subsequently in this chapter, which include a number of country-level quality of life assessmen ts. The UNDP Human Development Index, a country by country ranking of quality of life indicators, can be accesse d at http://hdr.undp. org/en/statistics/.

4 -5SAP 4.6 Chapter 4: Human Welfare

4.2.1.1 Health Focused Approaches
In medical science, quality of life is used as an outcom e variable to evaluate the effectiveness of medical, therapeutic, and/or policy interventions to promote population hea lth. Quality of life is an individual’s physiological state constituted by body structure, function, and capability that enable pursuit of stated and reve aled preferences. In medical scie nce, the concept of life quality is synonymous with good health – a life free of disease, illnes s, physical, and/or cognitive impairment (Raphael et al. , 1996, 1999, 2001).

In addition to objective measures of physical and occupational function, disease absence, or

soma tic sensation, life quality scie ntists measure an individual’s perception of life satisfaction.
The scientific basis of such research is that pain and/or discomfort associated with a physiological impairment are registered and expe rienced variably. Based on patient reports or subjective valuations, psychologists and occupa tional therapists have developed valid and
reliable instruments to assess how mental, developmental, and physic al disabilities interfere with the performance and enjoyment of life activities (Bowling, 1997; Guyatt et al. , 1993).

4.2.1.2 Economic and Psychological Approaches
Individual valuations of life quality also anc hor economic and psychologi cal investigations of happiness and utility. In the new science of happiness, scholars use the tools of neuroscience, experim ental research, and modern statisti cs to discover and quantify the underlying psychological and physiological sources of happiness (for reviews see Kahneman et al. , 1999; Frey and Stutzer, 2002; Kahneman and Krueger, 2006). Empirical studies show, for example, that life satisfaction and happiness correlate predictably with marital status (married persons are generally happier than single pe ople), religiosity (persons that practice religion report lower levels of stress and higher levels of life satisfaction), and individual willingness to donate time, money and effort to charitable causes. Simila rly, the scholarly literature notes interesting
statistical associations between f eatures of climate (such as varia tions in sunlight, temperature, and extreme weather events) and self-reported levels of happiness, utility, or lif e satisfaction.

Individual valuations of hea lth, psychological, and emotional well-being are som etimes summed across representative samples of a population or country to estimate correspondences between life satisfaction and “hard” indicators of living standards such as income, life expectancy, educational attainment, and environmental qualit y. Cross-national analyses generally find that population happiness or life satisfaction increases with income leve ls and material standards of living (Ng, 2003) and greater personal autonomy (Diener et al. , 1995; Diener and Diener, 1995). 5 In such studies, subjective valuations of life satisfact ion are embedded in broader conceptions of quality of life a ssociated with the conditions of a geographic place, community, region or country—the soci al indicators approach.

4.2.2 The Social Indicators Approach

In this second strand of research, what some refe r to as the social indi cators approach, scholars

assem ble location-specific measures of social, economic, and environmental conditions, such as

5 Some studies suggest that individual utility or happiness is not positively determined by some absolute quantity of income, wealth, or items consumed, but rather how an individual perceives his or her lot in relation to others or to conditions in their past. See, for example, Frank 1985.

4 -6SAP 4.6 Chapter 4: Human Welfare

employment rates, consumption flows, the ava ilability of affordable housing, rates of crime victimization and public safety, public monies invested in educa tion and transportation infrastructure, and local access to environmenta l, cultural, and recreational amenities. These place-specific variables are seen as exogenous sources of indivi dual life quality. Scholars reason that life quality is a bundle of conditions, amenities, and lifestyle options that shape stated and revealed preferences. In technical terms, the soci al indicators approach tr eats quality of life as a latent variable, jointly determined by several causal variables that can be measured with reasonable accuracy.

The indicators approach has seve ral advantages in the context of understanding the impacts of
clim ate change on human well-being. First, social indicators have consider able intuitive appeal, and their widespread use has not only made it familiar to both researchers and the general public, but has subjected them to consid erable debate and di scussion. Second, they offer considerable breadth and flexibility in terms of categories of human well-being that can be included. Third, for many of the indicators or dimensions of well- being, objective metrics exist for measurement.

In addition, while its strength is in providing indicators of prog ress on individual dime nsions of quality of life, the indicators approach has al so been used to support aggregate or composite measures, at least for purposes of ranking or m easuring progress. Various techniques are also available, or being developed, that aggregate or combine meas ures of well-being. These range from pure data reduction procedures to stakehol der input models where variables are evaluated
on their level of social and economic importance

. For example, Richard Florida (2002a) has
constructed a statistical index of technology, talent, and social tole rance variables to estimate the human capital of cities in the United States. Given the analytical strengths of the social indicators approach, it may be a good starting point for understanding the relationships between human well-being and climate change.

4.2.2.1 A Taxonomy of Categories of Wellbeing
Taxonomies of place-specific well-being or quality of life typically converge on six categories or dimensions: (1) economic conditions; (2) natural resources, environment, and amenities; (3) human health; (4) public and private infrastruc ture; (5) government and public safety; and (6) social and cultural resources. These categories re present broad aspects of personal and family circumstances, social structures, government, e nvironment, and the economy that influence wellbeing

. Table 4.1 illustrates these categories, which are listed in Column 1

. The third column, “components/indicators of welfare” provides examples of the way in which these categories are often interpreted. These components represent what, in an ideal world, res earchers would wish to measure in order to determine how a specific so ciety fares from the perspective of well-being. The fourth column provides illustrative metrics, i.e., objective or quantifiable measures that are often used by researchers as indicat ors of well-being for each category. 6 Finally, the last column provides some examples of climate impacts that may be linked to that category. This column should not be viewed as an attempt to create a comprehensive list of impacts, or even to list

6 Sources that contributed to the development of Table 1 include: MA (2005); Sufian, 1993; Rahman, 2007, and Lambiri, et al. , 2007. Insights were also derived from quality of life studies of individual cities and countries, including: http://www.bigcities.govt.nz/indicators.htm Quality of Life in New Zealand’s Large Urban Areas ; http://www.asu.edu/copp/morrison/public/qofl99.htm What Matters in Greater Phoenix 1999 Edition: Indicators of Our Quality of Life ; and http://www.jcci.org/sta tistics/qualityoflife.aspx Tracking the Quality of Life in
Jacksonville.

4 -7SAP 4.6 Chapter 4: Human Welfare

impacts with equal weights, in terms of importa nce or likelihood of occurrence. Further, while Table 4.1 focuses on negative impacts (as potentially more troubling for quality of life), there are also opportunities or potentia l positive impacts that will result in some categories.

These categories of well-being or life quality ar e interrelated. For example, as economic or social conditions in a society improve ( e.g., as measured by GDP per capita and rates of adult literacy), improvements occur in human health outcomes such as infant mortality, rates of morbidity, and female life expectancy at birth. Thus, while the categories and corres ponding metrics of wellbeing presented in Table 4.1 are an alytically separable, in reality they ar e highly interconnected. 7

Economics as a source of quality of life refers to a mi x of production, consumption, and exchange activities that consti tute the material well-being of a geographic place, community, region or country. Standard co mponents of economic well-being include income, wealth, poverty, employment opportunities, and costs of livi ng. Localities characterized by efficient and equitable allocation of economic rewards and opportunities enable ma terial security and subjective happiness of residents (Florida, 2002a).

Natural resources, environment, and amenities as a source of well-being refers to natural features, su ch as ecosystem services, species diversity, air and water qua lity, natural hazards and risks, parks and recreational amenities, and reso urce supplies and reserves . Natural resources and amenities directly and indirectly affect economic productivity, aesthetic a nd spiritual values, and human health (Blomquist et al. , 1988; Glaeser et al. , 2001; Cheshire and Magrini, 2006).

Human health as a source of well-being includes feat ures of a community, locality, region or country that influence risks of mo rtality, morbidity, and the availa bility of health care services.
Good health is desirable in itself as a driver of life expectancy (and the quality of life during those years), and is also cri tical to economic well-being by en abling labor force participation (Raphael et al. , 1996, 1999, 2001).

Public and private infrastructure sources of well-being incl ude transportation, energy and
communication technolo gies that enable comm erce, mobility, and social connectivity. These technologies provide basic conditions fo r individual pursuits of well-being ( Lambiri et al. , 2007).

Government and public safety as a source of well-being are ac tivities by e lected representatives
and bureaucratic officials that secure and maxi mize the public services, rights, liberties, and safety of citizens. Individuals derive happiness and utility from the employment, educational, civil rights, public service, and security efforts of th eir governments (Suffian, 1993).

Finally, social and cultural resources as a source of well-being are conditions of life that promote social harm ony, family and friendship, and the availability of arts, entertainment, and leisure activities that facilitate human happine ss. The terms social and creative capital have

7 More recently, scholars (Costanza et al. 2007) and government agencies ( like NOAA’s Coastal Service Center) have moved toward the global concept of capital to integrate indicators and asse ss community quality of life

. The term capital is divided into four types: economic; physical; ecological or natural; and socio-cultural. Various metrics constitute these types of capital, and are understood to fo ster community resilience and human needs of subsistence, reproduction, security, affection, unde rstanding, participation, leisure, sp irituality, creativity, identity, and freedom

. See also Rothman, Amelung, and Poleme (2003).

4 -8SAP 4.6 Chapter 4: Human Welfare

become associated with these factors. Communiti es with greater levels of social and creative capital are expected to have greater individual and community quality of life (Putnam, 2000; Florida, 2002b).

In thinking about these indicators, it is important to keep two important co ntextual realities about
climate chan ge and well-being at the forefront

. First, while discussions of climate change usually have a global resonance to them, the fact is that the effects of any specific changes in temperature, rainfall, storm fre quency/intensity and sea level rise will be felt at the local and regional level by citizens and co mmunities living and worki ng in those vulnerable areas

. Therefore, not all populations will be placed unde r equal amounts of climate change-generated

stress

. Some will experience greater impacts, will suffer greater damage, and will need more remediation and better plans a nd resource allocations for adapta tion and recovery efforts to protect and restore quality of life (see, for example, Zahran et al. , 2008; Liu, Vedlitz and Alston, 2008; Vedlitz et al. , 2007).

Second, not all citizens in areas mo re vulnerable to climate cha nge effects are equally at risk

. Some population groupings, within the same comm unity, will be more vulnerable and at risk
than others

. Those who are poorer, minorities, aged or in firmed, and children are at greater risk
than others to the stresses of climate cha nge events (Lindell and Perry, 2004; Peacock, 2003)

. Recognizing that not all citizens of a particular vulnerable area share the same level of risk is something that planners and decision makers mu st take into account in projecting the likely impacts of climate change events on their populations, and in dealing with recovery of those populations (Murphy and Gardoni, 2008).

Finally, the situation is further complicated as climate stresso rs nega tively affect disease conditions in other nations with partic ularly vulnerable and mobile populations

. Increased communicable disease incidence in developing nations have the poten tial, through legal and illegal tourism and immigration, to affect community welfare and individual well-being in the
United States.

4.2.2.2 Climate Change and Quality of Life Indicators
Social indicators are generally used to evaluate progress toward s a goal: How is society doing? Who is being affected? Tracking performance for these indicator s——using the types of metrics
or measures indicated in Table 4.1—could provide information to the public on how communities and other entities are reacting to, and successfully adapting to (or failing to adapt to), climate change. The indicators and metr ics included in Table 4.1 are intended to be illustrative of the types of indicators that might be used, rather than a comprehensive or recommended set. In any category, multiple indicators could be used; and any one of the
indicators could have several measures

. For example, exposure to natu ral hazards and risks could be measured by the percentage of a locality’s ta x base located in a high hazard zone, the number of people exposed to a natural h azard, the funding devoted to ha zard mitigation, or the costs of hazard insurance, among others

. Similarly, some indicators are more amenable to objective measurement; others are more difficult to measur e, such as measures of social cohesion. The point to be taken from Table 4.1 is that social indicators provide a divers e and potentially rich perspective on human well-being.

4 -9SAP 4.6 Chapter 4: Human Welfare

The taxonomy presented in Table 4.1—or a sim ilar taxonomy—might also provide a basis for analyses of the impacts of climate change on human well-being, providi ng a list of important categories for research (the com ponents or indicators of life quality), as well as appropriate metrics ( e.g., employment, mortality or morbidity, etc.). The social indicators approach, and the specific taxonomy presented here, are onl y one of many that could be developed. 8 At the least,
different conditions and stakeholder mixes may demand different emphases

. All taxonomies, however, face a common problem: how to interpret and use the diverse indicators, in order to compare and contrast alternative adaptive or mitigating responses to climate change

. For some purposes, metrics have been developed that th at aggregate across indi viduals or individual categories of well-being and present a compos ite measure of well-being; or otherwise operationalize related concepts, such as vulnerabi lity (see, for example the discussion of Figure 4.1).

Figure 4.1 Geography of Climate Change Vulnerability at the County Scale

4.2.3 A Closer Look at Communities
Looking beyond well-being of individuals to the welfare (broad ly speaking) of communities

— networks of households, businesses, physical stru ctures, and institutions—provides a broader perspective on the impacts of climate change. The categories and metrics in Table 4.1 are appealing from an analytical perspective in part because they represent dimensions of well-being that are clearly important to in dividuals, but that al so have counterparts and can generally be measured objectively at the community level. Th us, for example, the c ounterparts of individual income or health status are, at the social leve l, per capita income or mortality/illness rates. The concept of community welfare is linked to human communities, but is not confined to communities in urban areas, or ev en in industrialized cultures

. Human communities in remote areas, or subsistence economies, face the same ra nge of quality of life i ssues—from health to spiritual values—although they may place different weights on different values; thus, the weights placed on different components of welfare are not determined a priori , but depend on community values and decision making.

Viewing social indicators and me trics through the lens of the co mmunity can be instructive in several ways. First, communities are dynam ic entitie s, with multiple pathways of interactions among people, places, institutions, policies, struct ures, and enterprises. Thus, while the social
indicators described in Table 4.1 have metrics that can be measured independently of each other, they are not determined independently within the complex reality of interdependent human systems. Second, in part because of this interd ependence, the aggregate welfare of a community is more than a composite of its quality of life metrics; sustainability provides one means of approaching a concept of aggregate welfare. Third, vulnerability and adaptation are typically analyzed at the sectoral level: “what should agriculture, or the pub lic health system, do to plan for or adapt to climate change.” The issue can also, however, be addresse d at the level of the community. Each of these issu es is touched on below.

8 In addition to variants on the social indicators approach, other types of taxonomies are possible—for example a taxonomy based on broad systems (atmospheric, aquatic, ge ologic, biological, and built environment), or on forms of capital that make up the productive base of society (n atural, manufactured, human, and social). Well-being can also be viewed in terms of its endpoints: necessary materi al for a good life, health and bodily well-being, good social relations, security, freedom and choice, and peace of mind and spiritual existence (Rothman, Amelung, and Poleme

. , 2003).

4 -10SAP 4.6 Chapter 4: Human Welfare

4.2.3.1 Community Welfare and Individual Well-being
Rapid onset extreme weather events, such as hurri canes or tornadoes, can do serious dama ge to community infrastructure, public facilities and services, tax base, and overall community reputation and quality of life, fr om which recovery may take year s and never be complete (see additional discussion in Chapter 3). More gradual changes in te mperature and precipitation will have both negative and positive effects. For exampl e, as discussed elsewhere in this chapter, warmer average temperatures increase risks from heat-related mortality in the summer, but decrease risks from cold-related mortality in the winter, for susceptible p opulations. Effects such as these will not, however, be confined to a few individual sectors, nor ar e the effects across all sectors independent.

To illustrate the interdependence of impacts and, by extension , the analogous social indicators and metrics, consider a natural resource that faces additional stresses from climate change: fish populations in estuaries, such as the Chesapeak e Bay, that are already stressed by air and water pollution from industry, agriculture, and cities. In this case, while the direct effects of climate will occur to the resource itself, indirect effects can alter welfare as measured by economic, social, and human health indica tors. Table 4.2 presents some of the possible pathways by which resource changes could affect diverse categories of quality of life; the purpose of Table 4.2 is not
to assert that all these effects will occur or that they will be significant if they do occur as a result of climate change, but rather to illustrate th e linkages. These linkages underscore the importance of understanding interdependencies within the co mmunity or, from another perspective, across
welfare indicators

. Table 4.2 illustrates the ge neral principle of complex linkages in which a general equilibrium approach can be us ed to model climate change impacts.

4.2.3.2 Sustainability of Communities
Understanding how climate change and extreme events affect community welfare requires a different conceptual frame work than that for un derstanding individual le vel impacts, such as quality of life. 9 Communities are more than the sum of th eir parts; they have unique aggregate identities shaped by dynamic social, economic, a nd environmental components. They also have life cycles, waxing and waning in response to societal and environm ental changes (Diamond, 2005; Fagan, 2001; Ponting, 1991; Tainter, 1988). Sustainability is a paramount community goal, typically expressed in terms of sustaina ble development in order to express the ongoing process of adaptation into the long-term future . “Climate change involves complex interactions between climatic, environment, economic, politi cal, institutional, soci al, and technological processes. It cannot be addressed or comprehended in isolation from broader societal goals (such as sustainable development)...” (Banuri and Weya nt, 2001). Even for a country as developed as the US, continuing growth and development creates both pressures on the natural and built environments and opportunities for moving in sustainable directions

.

While the term sustainability does not have a si ngle, widely-accepted definition, a central guideline is to balance economic, environmental, and social needs and values (Campbell, 1996;

9 Measures of quality of life provide a database of rele vant individual characteristics at various points in time, including economic conditions, natural resources and amen ities, human health, public and private infrastructure, government and public safety, and social and cultural resources. Sustainable development measures are similar, but reflect more emphasis on long-term and reciprocal effects, as well as a co ncern for community-wide and equitable

outcomes.

4 -11SAP 4.6 Chapter 4: Human Welfare

Berke et al. , 2006), sometimes portrayed as a three-legge d stool. It is distinguished from quality of life by its dynamic linking of economic, environmental, and social components, and by its future orientation (Campbell, 1996; Porter, 2000). Sustaina bility is seen as living on nature’s “interest,” while protecting natural capital. Sust ainability is a comprehensive social goal that
transcends individual sector or impact measurements, a lthough it can include narrower community welfare concepts such as the healthy city . Thinking about the impacts of climate change on communities through the lens of sustaina ble development allows us to envision crosssector economic, environmental, and social dynamics.

4.2.4 Vulnerable Population s, Communities, and Adaptation
Responding to climate change at the community level requires understanding both vulnerability and adaptive responses that the community can take

. Vulnera bility of a community depends on its exposure to climate risk, how sensitive syst ems within that comm unity are to climate variability and change, and the adap tive capacity of the community ( i.e., how it is able to respond and protect its citizens from climate change). Different groups within the community will be differentially vulnerable to climate changes, su ch as extreme events, and infrastructure and community coping capacity will be more or less effective in invoking a resilient response to climate change.

4.2.4.1 Vulnerable Populations
Categories of persons susceptible to environmen tal risks and hazards include racial and ethnic groups (Bolin, 1986; Fothergill et al., 1999; Lindell and Perry, 2004; Cutter, 2006), and groups defined by econom ic variables of wealt h, income, and poverty (Peacock, 2003; Dash et al., 1997; Fothergill and Peek, 2004). Overall, research indicates that minorities and the poor are differentially harmed by disaster events. Ec onomic disadvantage, lower human capital, limited access to social and political res ources, and residential choices are social and economic reasons
that contribute to observed differences in disa ster vulnerability by race /ethnicity and economic
status. While the lite rature on climate change and vulne rable populations is relatively underdeveloped, Chapter 2 on Human Health and Ch apter 3 on Human Settlements each address population vulnerabilities.

Economic, social and health effects are not neatly bounded by geographic or political regions,
and so the dama ge and stresses that occur in a specific locality are not lim ited in their effects to only that community. As Hurricane Katrina made cl ear, impacts felt in one community ripple throughout the region and nation

. Persons made homeless in New Orleans resettled in Baton Rouge, Lafayette and Houston, creating stresses on those communities

. Vulnerable groups migrate from stricken areas to more hospitable ones, taking their health, economic and educational needs and problems with them across both national and state lines

4.2.4.2 Vulnerable Communities
While most analyses of vulnerability tend to be conducted at the re gional scale, Zahran et al. (2008) have brought the analysis closer to the community le vel by ma pping the geography of climate change vulnerability at the county scale. The study uses measures of both physical vulnerability (expected temperature change, extreme w eather events, and coastal proximity) and adaptive capacity (as represented by economic, demographi c, and civic participation variables that constitute a locality’s socioeconomic capac ity to commit to costly climate change policy

4 -12SAP 4.6 Chapter 4: Human Welfare

initiatives). Their map identifies the concentra tions of highly vulnerabl e counties as lying along the east and west coasts and Great Lakes, with medium vulnerability counties mostly inland in the southeast, southwest, and northeast. (See Fi gure 4.1, in which darker areas represent higher vulnerability).

Many possible dimensions can be used to identify and measure vulnerabili ties to clim ate change impacts and stressors

. The one presented in Figure 4.1 illustrates that the concept of vulnerability
is a viable one and can be measured and applied to communities in a GIS context

. It is not the purpose of this chapter to focus in great detail on vulnerability measurement issues (for those
interested in other formulations of the vulnerability concept, see Dietz et al. , In Press).

4.2.4.3 Adaptation
From the perspective of the community, the goa l of successful adaptati on to climate impacts— particularly potentially adverse im pacts—is to ma intain the long-term sust ainability and survival of the community. Thus, a resili ent community is capable of absorbing climate changes and the
shocks of extreme events without breakdowns in its economy, natural resource base, or social systems (Godschalk, 2003). Given their control over shared resources, communities have the capacity to adapt to climate change in larger and more coordinated ways than individuals, by creating plans and strategies to in crease resilience in the face of future shocks, while at the same time ensuring that the negative impacts of clim ate change do not fall disproportionately on their most vulnerable populations and demogra phic groups (Smit and Pilifosova, 2001).

Public policies and programs are in place in th e Un ited States to enha nce the capacity of communities to mitigate 10 damage and loss from natural hazards and extreme events (Burby, 1998; Mileti, 1999; Godschalk, 2007). A considerab le body of research looks at responses to natural hazards, and recent research has shown th at the benefits of natural hazard mitigation at the national level outweigh its costs by a factor of four to one on average (Multihazard Mitigation Council, 2005; Rose et al. , 2007). Research also has been done on the social vulnerability of communities to natural hazards (Cutter et al. , 2003) and the economic resilience
of businesses to natural hazards (Tierney, 1997; Rose, 2004). Howeve r, there is scant research on U.S. policies dealing with community adaptation to the broader impacts of climate change.



### 4.3 An Economic Approach to Human Welfare

Welfare, well-being, and quality of life are ofte n viewed as multi-faceted concepts. In subjective assessments of happiness or quality of life (s ee the discussion in Sect ion 4.2), the individual
makes a net evaluation of his or her current stat e, taking into account (at least implicitly) and balancing all the relevant facets or dimensions of that state of being. Constructing an overall statement regarding welfare from a set of obj ective measures, however, requires a means of weighting or ranking, or otherwis e aggregating, these measures. The economic approach supplies one—although not the only possibl e—approach to aggregation. 11

10 In the natural hazards and disasters field, a single term—mitig ation—refers both to adaptation to hazards and mitigation of their stresses. (See the Disaster Mitigation Act of 2000, Public Law 106-390.)

11 In part because of the difficulty in compiling the information needed for aggregation of economic measures, Jacoby (2004) proposes a portfolio approach to benefits estimation, focusing on a limited set of indicators of global climate change, of regional impact, and one global moneta ry measure. The set of measures would not be the only

4 -13SAP 4.6 Chapter 4: Human Welfare

Quantitative measures of welfare that use a comm on metric ha ve two potential advantages. First, the ability to compare welfare impacts across di fferent welfare categorie s makes it possible to identify and rank categories with regard to the magnitude or importance of effects. Welfare impacts can then provide a signal about the relativ e importance of different impacts, and so help to set priorities with regard to adaptation or research. Second, if the concept of welfare is (ideally) a net measure, then it should be possi ble to aggregate the e ffects of climate across disparate indicators. Quantitative measures that use the same metric can, potentially, be summed to generate net measures of welfare, and gauge progress over time, or under different policy or adaptation scenarios.

Given the value of welfare both as a multi-dimens ional concep t, and as one that facilitates comparisons, the economic approach to welfare an alysis—which monetizes or puts dollar values on impacts—is one means of comparing disparat e impacts. Further—and this is the second advantage of the economic approach—dollar valu es of impacts can be aggregated, and so provide net measures of changes in impacts that can be useful to policy makers. This section of the chapter discusses th e foundation of economic valuation, th e distinction between market and non-market effects (only the latter are covered in this paper), and describes some of the valuation
tools that economists use for non-ma rket effects. An appendix cove rs these issues in additional detail, and also describes the challenges that eco nomic valuation faces when used as a tool for policy analysis in the long term context of climate change.

Fundamental to the economic approach is a no tion that a key element of support for decisionm aking is an understanding of the magnitude of co sts and benefits, so that the tradeoffs implicit in any decision can be balanced and compar ed. However, the economic approach, when interpreted as requiring a strict cost-benefit test, is not appropriate in all circumstances, and is viewed by some as controversial in the context of climate change. 12 Benefit cost analysis is one
tool available to decision makers ; in the context of climate change; other decision rules and tools, or other definitions of welfare, may be equally, or more relevant

. For example, the recent Synthesis Report of the IPCC Fourth Assessment (IPCC, 2007a) presents an average social cost ( i.e., damages) of carbon in 2005 of $12 per ton of CO 2 , but also notes that the range of the roughly 100 peer-reviewed estimates of this value is -$3 to $95/tCO 2

. 13 IPCC attributes this very broad range to differences in assumptions on clim ate sensitivity, response lags, the treatment of risk and equity, economic and non-economic impact s, the inclusion of potentially catastrophic losses, and discount rates

. IPCC therefore suggests consideration of an "iterative risk management process" to support decision-making. 14 Estimated benefits and costs therefore can provide information relevant to decision make rs, but some of the methodologies and data

information generated and made available, but it would re presen t a set of variables continuously maintained and used to describe policy choices.

12 See Arrow et al. , 1996 - at page 7, "There may be factors other th an economic benefits and costs that agencies will want to weigh in decisions, such as equity within and across generations

. In addition, a decision maker may want to place greater weight on particular charac teristics of a decision, such as pote ntial irreversible consequences."

13 See IPCC 2007a, page 23.

14 IPCC further notes that existing analyses suggest costs and benefits of mitigation are roughly comparable in magnitude, "but do not as yet permit an unambiguous determ ination of an emissions pa thway or stabilization level where benefits exceed costs." (IPCC 2007a page 23).

4 -14SAP 4.6 Chapter 4: Human Welfare

necessary to provide a relatively complete assessment may be unavailable, as discussed subsequently in this section. 15

4.3.1 Economic Valuation
The framework that economists employ reflects a specific view of huma n welfare and how to
measure it. Economists define the value of so mething—be it a good, service, or state of the world—by focusing on the well-being, utility, or level of satisfaction that the individual derives. The basic economic paradigm assu mes that individuals allocate their available income and time to achieve the greatest level of satisfaction. The value of a good—in terms of the utility or satisfaction it provides—is reve aled by the tradeoffs that individuals make between that good and other goods, or between that good and income. 16 The term “willingness to pay” (WTP) is used by economists to repres ent the value of something, i.e., the individual’s willingness to trade money for that particular good, se rvice, or state of the world.

Economists distinguish between market and non-m arket goods. Market goods are those that can be bought and sold in the ma rket, and for which a price generally exists. Market behavior and, in particular, the prices that ar e paid for these goods, is a sour ce of information on the economic value or benefit of these goods. The economic benefit—the amount that members of society would in aggregate be willing to pay for these goods—is related t o, but frequently greater than, market prices.

Non-market goods are those that are not bought a nd sold in ma rkets. Consequently, climate change impacts that involve non-market effects— such as health effects, loss of endangered species, and other effects—are difficult to value in monetary terms. Economists have developed techniques for measuring non-market values, by inferring economic value from behavior (including other market behavior), or by asking individuals directly.

A number of studies have attemp ted to value the range of effect s of climate change. For the US,

som e of the most comprehensive studies are th e Report to Congress completed by U.S. EPA in 1989 (U.S. EPA, 1989), Cline (1992), Nordhaus (1994), Fankhauser (1995), Mendelsohn and Neumann (1999), Nordhaus and Boyer (2000) , and a body of work by Richard Tol ( e.g., Tol, 2002 and Tol, 2005). In all of these studies, the focu s is largely on market impacts, particularly the effects of climate change on agriculture, fo restry, water resource av ailability, energy demand (mostly for air conditioning), coastal property, and in some cases, health.

Non-market effects, however, are less we ll char acterized in these studies (Smith et al. , 2003); where comprehensive attempts are made, they us ually involve either expert judgment or very rudimentary calculations, such as multiplying the numbers of coastal wetland acres at risk of inundation from sea-level rise by an estimate of the average non-market value of a wetland. One such comprehensive attempt generated a value for 17 ecosystem services from 16 ecosystem types (Costanza et al. , 1997), but also generated contr oversy and critic ism from many

15 Other factors that might be considered, in addition to economic estimates, include emotions, perceptions, cultural values, and other subjective factors, all of which can pl ay a role in creating prefer ences and reaching decisions

. Those factors are beyond what we can evaluate in this chapter

. 16 Although economists are careful to distinguish between the metrics of utility and money as distinct, valuation metric in dollar units (rather than units of utility) may be generally viewed as the outc omes of individual preference expressions among goods, income, and time.

4 -15SAP 4.6 Chapter 4: Human Welfare

economists (Bockstael et al. , 2000; Toman, 1998; see National Research Council 2004 for a summary). Other analysts have attempted to defi ne measures to reflect non-market ecosystem
services in terms similar to those used for Gr oss Domestic Product (Boyd, 2006), or indicators of ecosystem health that reflect ecological cont ributions to human welfare (Boyd and Banzhaf, 2006). 17 While there are several well-done valuati on analyses for non-market effects of climate change (as described later in this chapter), it is fair to characterize this l iterature as opportunistic in its focus; where data and met hods exist, there are high quality studies, but the overall coverage of non-market effects remains inadequate.

4.3.2 Impacts Assessment and Monetary Valuation
The process of estimating the welf are effects of climate change i nvolves four steps: (1) estim ate climate changes; (2) estimate physical effects of climate change, (3) estimate the impacts on human and natural systems that are amenable to valuation and (4) value or monetize effects. The first step requires estimating the change in rele vant measures of climate, including temperature, precipitation, sea-level rise, and the frequency an d severity of extreme events. The second step involves estimating the physical eff ects of those changes in climat e. Such effects might include changes in ecosystem structure and function, human exposures to heat stress, changes in the geographic range of disease vector s, or flooding of coastal areas. In the third step, the physical effects of climate change are translated into measures that economists can value, for example the number and location of propertie s that are vulnerable to floods , or the number of individuals exposed to and sensitive to heat stress. Many analys es that reach this step in the process, but not all, also proceed on to the fourth ste p, valuing the changes in dollar terms. .

The simplest approach to valuation would be to apply a unit valuation ap proach - for example,
the cos t of treating a nonfatal case of heat stress or malaria attributable to climate change is a first approximation of the value of avoiding that case altogether. In many contexts, however, unit values can misrepresent the true marginal econo mic impact of these changes. For example, if climate change reduces the length of the ski season, individuals coul d engage in another recreational activity, such as golf. Whether they might prefer skiing to golf at that time and location is something economi sts might try to measure.

This step-by-step linear approach to effect s estimation is sometim es called the "damage function" approach. A damage function approach mi ght imply that we look at effects of climate on human health as separate and independent from effects on ecology and recreation, an assumption that ignores the complex economic in terrelationships among goods and services and individual decisions regarding these. Recent research suggests that the damage function approach, under some conditions, may be both ov erly simplistic (Freeman, 2003) and sometimes subject to serious errors (Str zepek and Smith, 1995; Strezpek et al. , 1999).

Economists have a number of techniques availabl e for moving from quantified effects to dollar values. In some cases, the values estimated in one situation— e.g., one ecosystem or species—
can be transferred and used to value another

. For example, value or benefits transfer is commonly used by federal agencies such as the US EPA and US Forest Service to value
recreation when there is insufficient time or budget to conduct original valuation studies

17 Some political economists also emphasize the role of exp licit recognition of non-market environmental values as an important step in improving the well-being of poor populations (Boyce and Shelley, 2003).

4 -16SAP 4.6 Chapter 4: Human Welfare

(Rosenberger and Loomis, 2003)

. Techniques commonly used by economists to value nonmarket goods and services include:

 Revealed preferen ce

. Revealed preference, sometimes referred to as the indirect valuation approach, involves inferring th e value of a non-market good using data from market transactions (U.S. EPA, 2000; Freeman, 2003)

. For example, the value of a lake for its ability to provide a good fishing experien ce can be estimated by the time and money expended by the angler to fish at that particul ar site, relative to a ll other possible fishing
sites

. Or, the amenity value of a coastal property that is protected from storm damage (by a dune, perhaps) can be estimated by compar ing the price of that property to other properties similar in every way but the enhanced storm protection

.

 Stated preference . Stated preference m ethods, some times referred to as the direct valuation, are survey methods that estimate the value individuals place on particular nonmarket goods based on choices they make in hypothetical markets

. The earliest stated preference studies involved simp ly asking individuals what th ey would be willing to pay for a particular non-market good

. The best studies involve gr eat care in constructing a credible, though still hypothe tical, trade-off between mone y and the non-market good of interest (or bundle of goods) to discern individual preferen ces for that good and hence,

WTP

.

 Replacement or avoided costs

. R eplacement cost studies appr oach non-market values by estimating the cost to replace the services provided to individuals by the non-market good

. For example, healthy coastal wetlands may provide a wide range of services to individuals who live near them (such as filtering pollutants present in water). A replacement cost approach would estimate the value of these services by estimating market costs for replacing the se rvices provided by the wetlands

. Analogously, the cost of health effects can be estimated using the cost of treating illness and of the lost workdays,
etc. associated with illness

.

 Value of inpu ts . This approach calculated value base d on the contribution of an input into some productive process. This approach can be used to determine the value of both market and non-market inputs, for example, fe rtilizer, water, or soil, in farm output and profits

In the remainder of this section, we briefly di scuss the relationship between climate change and
four non-ma rket effects (human health, ecosystem s, recreation and tourism, and amenities), and
discuss economic estimates of thes e effects using these techniques.

4.3.3 Human Health
In the US, climate change is likely to measurab ly affect health outcome s known to be associated with weather and climate, including heat-related illnesses and deaths , health effects due to storms, floods, and other extreme weather events, h ealth effects related to poor air quality, waterand food-borne diseases, and insect-,tick-,and rode nt-borne diseases. In addition to changes in mortality and morbidity, climate change may affecthealth in more subtle ways. Good health is more than the absence of illness; it includes ment al health, the ability to function physically (to climb stairs or walk a mile), socially (to move freely in the world), and in a work environment. Please see Chapter 2 of this report, which provides an overview of health effects that have been associated with climate change.

4 -17SAP 4.6 Chapter 4: Human Welfare

Despite our understanding of the pathways linking c limate and health effects, there is uncertainty
as to the m agnitude and geographic and temporal variation of possible impacts on morbidity and mortality in the US, primarily due to a poor understanding of many key risk factors and confounding issues, such as behavi oral adaptation and variabili ty in population vulnerability (Patz et al. , 2001). Even where our unders tanding of underlying climate and health relationships is better, few studies have attempted to explicit ly link these findings to climate change scenarios to quantitatively estimat e health impacts. Economists have relatively well established (although sometimes controversial) techniques for valui ng mortality and some forms of morbidity, which could, in theory be applied to quantified impacts assessments.

4.3.3.1 Overview of Health Effects of Climate Change
The US is a developed country with a temper ate climate. It has a well-developed health infrastructure and governm ent a nd non-governmental agencies invol ved in disaster planning and response, both of which can help to mitigate potential health effects from climate change. Nevertheless, certain regions of the US will f ace difficult challenges arising from some of the following health effects.

 Illnesses and deaths due to heatwaves . A likely impact in the US is an inc rease in the severity, duration, and frequency of heatwa ves (Kalkstein and Greene, 1997; IPCC, 2007c). This, coupled with an aging (and therefore more vulnerable) population, will increase the likelihood of higher mortality fr om exposure to excessive heat (see, for example, Semenza et al. , 1996, and Knowlton et al., 2007).

 Injuries and death from extreme weather events . Clim ate change is pr ojected to alter the frequency, timing, intensity, and duration of extreme weather events, such as hurricanes and floods (Fowler and Hennessey, 1995). The he alth effects of th ese extreme weather events range from the direct effects, such as loss of life and acute trauma, to indirect effects, such as loss of she lter, large-scale population displacement, damage to sanitation infrastructure (drinking water and sewage systems), interruption of food production, damage to the health care infrastructure, and psychological problems such as post traumatic stress disorder (Curriero et al. , 2001).

 Illnesses and deaths due to poor air quality . Clim ate change can affect air quality by modifying local weather patterns and polluta nt concentrations (such as ground level ozone), by affecting natural sources of air pollution, and by changing the distribution of airborne allergens (Morris et al. , 1989; Sillman and Samson, 1995). Many of these effects are localized and, for ozone, compounded by assumptions of trends in precursor
emissions

. Despite these uncertainties, all else being equal, climate change is projected to
contribute to or exacerbate ozone-related illnesses.

 Water- and Foodborne Diseases

. Altered weather patterns , including changes in precipitation, temperature, humidity, and water salinity, are likely to affect the distribution and prevalence of food- and waterborne diseas es resulting from bacteria, overloaded drinking water systems, and increas es in the frequency and range of harmful algal blooms (Weniger et al. , 1983; MacKenzie et al. , 1994; Lipp and Rose, 1997;
Curriero et al. , 2001).

 Insect-, Tick-, and Rodent-borne Diseases . Vector-borne diseases, such as plague, Lyme’s disease, malaria, hanta virus, and dengue fever have distin ct seasonal pattern,

4 -18SAP 4.6 Chapter 4: Human Welfare

suggesting that they may be sensitive to climate-driven changes in rainfall and temperature (Githeko and Woodward, 2003). Moderating factors, such as housing quality, land-use patterns, vector contro l programs, and a robust public health infrastructure, are likely to prevent the large-sc ale spread of these diseases in the United
States.

4.3.3.2 Quantifying the Hea lth Impacts of Climate Change
A large epidemiological literature exists on the he alth effects associated with climate change, particularly the m ortality effects associated with increases in aver age monthly or seasonal temperature, and with changes in the intens ity, frequency, and durati on of heatwaves. As described in Chapter 2, there is considerable speculation concerning the balance of climate change-related decreases in winter mortality compared with increases in summer mortality, although researchers suspect that declines in winter mortality associated with climate change are unlikely to outweigh increases in summer mortality (McMichael et al. , 2001; Kalkstein and Greene, 1997; Davis, 2004).

Net changes in mortality are difficult to estimate because, in part, mu ch depends on complexities in the relationship between mortality and th e changes associated with global change

. Using average temperatures to estimate cold-related mort ality, for example, is complicated by the fact that many factors contribute to wi nter mortality (such as spread of the influenza virus). Similarly, increased summer mortality may be affected not only by average temperature, but also by other temperature factors, such as vari ability in temperature, or the du ration of heat waves. Moreover, quantifying projected temperatur e-related mortality requires goi ng beyond epidemiology and (for example) projecting adaptive behaviors, such as the use of air c onditioning, expanded public programs (such as heat warning sy stems), or migratory patterns.

Few studies have attempted to link the epidemio logical findin gs to climate scenarios for the United States, and studies that have done so ha ve focused on the effects of changes in average temperature, with results dependent on c limate scenarios and assumptions of future adaptation. 18 Moreover, many factors contribute to winter mortality, making highly uncertain how climate change could affect mortality. No pr ojections have been published for the U.S. that incorporate critical factors, such as the influe nce of influenza outbreaks. Below, we report the results of these studies in order to give a sense of the magnitude of mortality that might be associated with temperature changes associated with climate change and, by intimation, the magnitude of potential changes in economic welf are. The conclusions should be considered preliminary, however, in part because of the co mplexities in estimating mortality under future climate scenarios. Moreover, none of the studies reported below traces through the quantitative implications of various climate scenarios for mort ality in all regions of the United States using region-specific data, suggesting a clear need for future research.

18 McMichael et al. (2004) estimate the impact of climate change on DALYs (Disab ility-Adjusted Life Years)
associated with waterborne and vector-borne illness for WHO regions. (DALYs represent the sum of life-years lost due to premature death and productive life years lost due to chronic illness or injury.) For the US, it is not anticipated that climate change will lead to loss of life or years of life due to chronic illness or injury from
waterborne or foodborne illnesses. Howe ver, there will likely be an increase in the spread of several food- and water-borne pathogens among susceptible populations depending on the pathogens' survival, persistence, habitat range and transmission under changing climate and environmental conditions.

4 -19SAP 4.6 Chapter 4: Human Welfare

Quantifying the relationship between climate change and cases of injury, illness, or death requires an exposure-response func tion that quantifies th e relationship between a health endpoint ( e.g., premature mortality due to cardiovascular di sease (CVD), cases of diarrheal disease) and climate variables ( e.g., temperature and humidity). The expo sure-response function can be used to compute the relative risk of illness or d eath due to a specified change in climate, e.g., a temperature increase of 2.5°C. Applying this relative risk to the baseline incidence of the illness or death in a population yields an estimated number of cases associated with the climate
scenario.

Two studies have attempted to link exposure-response functions to future climate scenarios and thereby d evelop temperature-related mortality estimates. 19 McMichael et al. (2004) estimate the effects of average temperature changes associ ated with projected climates resulting from alternative emissions scenarios, by WHO region

. For the AMR-A region, which includes the United States, Canada, and Cuba, they estimate th e impact on cardio-vascular mortality relative
to baseline conditions in 1990

. Effects are estimated for average temperature projections
associated with three altern ative emissions scenarios: (1 ) no control of GHG emissions, 20 (2) stabilization at 750 parts-per-million (ppm) of CO 2 equivalent by 2210, and (3) stabilization at 550 ppm CO 2 equivalent by 2170. 21

McMichael et al. (2004) bases the estimates of the eff ects of average temperature changes on mortality from cardio-vascular disease (CVD) for AMR-A on Kunst et al. (1993)

. Kunst et al. (1993) find CVD mortality rates to be lowest at 16°C, and to increase by 0.5% for every degree C below 16°C and increase by 1.1% for each degree above 16°C

. In applying these results to future climate scenarios, McMichael et al. (2004) assume that people will adjust to higher average temperatures; thus, the temperature at wh ich mortality rates reach a minimum is adjusted by scenario

. No adjustment is made for attempts to mitigate the effects of higher temperatures through (for example) increas ed use of air-conditioning

. The effect of the climate scenarios for the North American region (AMR-A), reporte d for 2020 and 2030, is, on net, zero—reductions in CVD mortality due to warmer winter temperat ures cancel out increases in CVD mortality due
to warmer summer temperatures

.

Hayhoe et al. (2004) examine the impacts on clim ate a nd health in California of projected climate change associated with two emissions s cenarios. The emissions scenarios are similar to
those used in McMichael et al. (2004): (1) stabiliza tion at 970 ppm of CO 2 and (2) stabilization at 550 ppm of CO 2

. 22 In Los Angeles, by the end of th e century, the number of heatwave days (3 or more days with temperatures above 32 °C) increases fourfold under scenario B1 and six to eight times under scenario A1fi

. From a baseline of 165 excess deat hs in the 1990s, heat-related deaths in Los Angeles are projecte d to increase two to three time s under scenario B1 and five to seven times under scenario A1fi by 2090.

19 These studies use climate scenarios th at are associated with different emis sions scenarios from IPCC (2000), the
so-called SRES scenarios.

20 McMichael et al. (2004) represent unmitigated emissions using th e IS92a emissions scenario presented in IPCC (2000).

21 Climate scenarios are projected for 2025 and 2050 using the HadCM2 model at a resolution of 3.75 ◦ longitude by
2.5 ◦ latitude and interpolated to other years

. 22 Hayhoe uses two SRES (IPCC 2000) emissions scenarios: A1fi (corresponding to 970 ppm of CO 2 ) and B1 (corresponding to 550 ppm of CO 2 ).

4 -20SAP 4.6 Chapter 4: Human Welfare

These results can be compared with those of an earlier study that employed a com posite climate variable to examine the impact of extreme temp eratures on daily mortality under future climate scenarios. Kalkstein and Greene (1997) analyzed the effect of temperature extremes (both hot and cold) on mortality for 44 US cities in the su mmer and winter. They then applied these results to climate projections from two GCMs fo r 2020 and 2050. In 2020, under a no-control scenario, excess summer deaths in the 44 cities were estimated to increase from 1,840 to 1,981-4,100, depending on the GCM used. The corres ponding figures for 2050 were 3,190-4,748 excess
deaths.

4.3.3.3 Valuation of Health Effects
In benefit-cost analyses of health and safety programs, mortality risks are commonly valued using the “value of a statisti cal life” (VSL)—the sum of what people would pay to reduce their risk of dying by small amounts that, together, add up to one statistical life. This approach allows valuation economists to focus on how people res pond to and implicitly value mortality risk in their daily decisions, rather than attempting to value the lives lost, per se (U.S. EPA, 2000)

. This approach also responds to the type of data that is typically available; the excess deaths associated with a particular climat e scenario are indeed the number of statistical lives that would be lost

.

Willingness to pay for a current re duction in risk of death ( e.g ., over the coming year) is usually estimated from compensating wage differentials in the labor market (a revealed preference method), or from contingent valuation surveys (a stated preference method) in which people are asked directly what they would pay for a reduc tion in their risk of dying. The basic idea behind compensating wage differentials is that jobs can be characterize d by various attributes, including
risk of accidental death. If workers are well-informed about ri sks of fatal and non-fatal injuries, and if labor markets are competitive, riskier jobs should pay more, holding worker and other job attributes constant (Viscusi, 1993). In theory, the impact of a small change in risk of death on the wage should equal the amount a worker would have to be compensated to accept this risk. For small risk changes, this is also what the worker should pay for a risk reduction.

For the compensating wage approach to yield reliab le estima tes of the VSL, it is necessary that workers be informed about fatal job risks and that there be sufficient competition in labor markets for compensating wage differentials to emerge. 23

. To measure these differentials empirically requires accurate estimates of the risk of death on the job—ideally, broken down by industry and occupation. The resear cher must also be able to in clude enough other determinants of wages that fatal job risk does not pick up the effects of other worker or job characteristics. Empirical estimates of the valu e of a statistical life base d on compensating wage studies conducted in the U. S. lie in the range of $0.6 million to $13.5 million (1990 dollars) (Viscusi, 1993; U.S. EPA, 1997), which is the rough equiva lent of $0.7 million to $16.5 million in year
2000 dollars. 24

23 Estimates of compensating wage differentials are often quite sensitive to the exact specification of the wage equation

. Black et al. (2003), in a reanalysis of data from U.S. compensating wage studies requested by the USEPA, conclude that the results are too unstable to be used for policy.

24 Adjusted using the GDP implicit price deflator produced by the Bureau of Economic Analysis US Department of Commerce, available at http://www.bea.go v/national/nipaweb/TableView.asp#Mid

4 -21SAP 4.6 Chapter 4: Human Welfare

This challenge is compounded by the long-term na ture of climate risks, which suggests that
much of the premature mortality associated with higher temperatures wi ll occur in the future

. Indeed, McMichael et al. (2004) and Kalkstein and Greene (1997) estimate mortality based on
climate effects around the years 2020 and 2050; Hayhoe et al. (2004) analyze impacts in 2070-
2099.

It is also the case that the major ity of the hea lth effects of climate change will be felt by persons 65 and over. Recent attempts to examine how th e VSL varies with worker age (Viscusi and Aldy, 2007) suggest that the VSL ranges from $9.0 million (2000 dollars) for workers aged 35- 44 to $3.7 million for workers aged 55-62. Contingent valuati on studies (Alberini et al. , 2004) also suggest that the VSL may decline with ag e. Further, economic theory suggests that, under some assumptions, persons are willin g to pay less to reduce a risk they will face in the future (say, at age 65) than they are willing to pa y to reduce a risk they face today (Cropper and Sussman, 1990). Both these factor s may affect the economic value that would be attached to excess mortality estimates, such as thos e derived by Kalkstein and Greene (1997).

The potential health effects associated with clim ate change are mu ch broader than the changes in excess mortality discussed above. The effects of climate on illness have been examined in the literature, as indicated in the pr evious section; however, there have been few attempts to examine the implications of these studies for future clim ate scenarios. In addition to quantified estimates of mortality and morbidity, themselves indicat ions of well-being and welfare, a range of economic techniques that have been developed for use in cost-benefit analyses of health and safety regulations could be a pplied to many of the endpoints that may be affected by climate change, as suggested by Table 4.3. Before these methods could be applied, however, the impacts of climate change must be translated into physical damages.

It is also the case that good health is more than the absence of illness. All of the dimensions of functioning measured in standard questionnaires (including various health outcomes surveys (HCFR, 2004) may be affected by changes in clim ate. From a valuation perspective, we would expect changes in functional lim itations (stiffness of joints, diffi culty walking) not to be linked directly to climate or to weathe r, but rather to be instrumental in people’s location decisions and, thus, reflected in wa ges and property values

. The relationship between climate and wages and property values are discussed in the subsequent section on Amenity values.

4.3.4 Ecosystems
Human welfare depends on the Ea rth’s ecosystems and the services that they provide, where
ecosystem services may be defined as “the c onditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life” (Daily, 1997).
These services contribute to hum an well-being and welfare by c ontributing to basic material needs, physical and psychological health, securit y, and economic activity, and in other ways (see Table 4.4). For example, a variety of ecosystem changes may be linked to changes in human health, from changes that encourage the expans ion of the range of v ector-borne diseases (discussed in Chapter 2) to the frequency and impact of floods and fires on human populations, due to changes in protection afforded by ecosystems.

4 -22SAP 4.6 Chapter 4: Human Welfare

The ability of the biosphere to c ontinue providing these vital goods and services is being strained by human activities, such as habita t destruction, releases of polluta nts, over-harvesting of plants, fish and wildlife, and the introduction of invasi ve species into fragile systems. The recent Millennium Ecosystem Assessment reported that of 24 vital ecosystem services, 15 were being degraded by human activity (MA, 2005). Climate change is an additional human stressor that threatens to intensify and extend these advers e impacts to biodiversity, ecosystems, and the services they provide.

Changes in temperature, precipitation, and other effects of climate change will have di rect effects on ecosystems. Climate change will also indirectly affect ecosystems, via, for example,
effects of sea level rise on coas tal ecosystems, decision-makers’ responses to climate change (in terms of coastline protection or land use), or increased demands on water supplies in some locations for drinking water, electricity generation, and agricultural use. Understanding how these changes alter economic welfare requires identifying and potentially valuing changes in ecosystems resulting from climate change. Getti ng to the point of valuation, however, requires establishing a number of linkages—from projected changes in climate to ecosystem change, to changes in services, to changes in the value of those services—as illust rated in Figure 4.2. The scientific community has not, thus far, focuse d explicitly on establishing these linkages in the context of climate change. Consequently, the published literature is somewhat fragmented, consisting of discussions of climate effects on ec osystems and of valuation of ecosystems and their services (in only a few cases do the latter focus on climate change).

Figure 4.2 Steps from Climate Change to Economic Valuation of Ecosystem Services

Already observed effects (see reviews in Parmesan and Yohe, 2003; Root et al.

, 2003; Parmesan and Galbraith, 2004) and modeling results indicate th at climate change is very likely to have major adverse impacts on ecosystems (Peters and Lovejoy, 1992; Bachelet et al. , 2001; Lenihan
et al. , 2006; Galbraith et al., 2006). It is also likely that thes e changes will adversely affect the services that humans and human systems derive from ecosystems (MA, 2005). Climate change may affect ecosystems in the US within this century in the following ways.

Shifting, breakup and loss of ecological communities. As climate changes, species that are components of communities will be forced to shif t their ranges to follow cooler temperatures either poleward or upward in elev ation. In at least some cases, this is likely to result in the breakup of communities as organisms respond to te mperature change and migrate at different rates. In general, study projecti ons include: northern extensions of the ranges of southern broadleaf forest types, with nor thward contractions of the rang es of northern and boreal conifer forests; elimination of alpine tundra from much of its current ra nge in the United States; and the replacement of forests by grasslands, shrub-domin ated communities, and savannas, particularly in the south ( e.g., VEMAP, 1995; Melillo et al. , 2001; Lenihan et al. , 2006). Because of different
intrinsic rates of migration, communities may not move intact into new areas (Box 4.1).

Another potential community eff ect of climate change is th e facilitation of comm unity penetration and degradation by invasive weeds th at will replace more sensitive native species (Malcolm and Pitelka, 2000)

4 -23SAP 4.6 Chapter 4: Human Welfare

Extinctions of plants and anim als and reduced biodiversity. While s ome species may be able to adapt to changing climate conditions, others will be adversely affected. It is very likely that
one result of this will be to accelerate current extinction rates, resulting in loss in biodiversity. The most vulnerable species within the United Stat es may be those that ar e currently confined to small, fragmented habitats that may be sensitive to climate change. This is the case with Edith’s checkerspot, a western butterfly species that is already undergoing local subpopulation extinctions due to climate change (Parmesan, 1996). Other potentially vulnerable organisms
include those that are restricted to alpine tundra habitats (Wang et al. , 2002), or to coastal habitats which may be inundated by sea level rise (Galbraith et al. , 2002).

Range shifts. Faced with increasing temperatures, populatio ns of plants and animals will attempt to track their preferred climatic conditions by sh ifting their ranges. Range shifts will be limited by factors such as geology (in the case of plants that are confined to certain soil types), or the presence of cities, agricultural land, or other human activities that block northward migration. Some individual species in Nort h America and the US are alrea dy undergoing range shifts (Root
et al.

, 2003; Parmesan and Galbraith, 2004). The red fox in the Canadian arctic shifted its range northward by up to 600 miles during the 20th cen tury, with the greate st expansion occurring where temperature increases have been the la rgest (Hersteinsson and Macdonald, 1992). More generally, a number of bird spec ies have shifted their ranges north ward in the United States over the past few decades. While some of these changes may be attributable to non-climatic factors, it is very likely that some are due to climate change (Root et al.

, 2003; Parmesan and Galbraith, 2004).

Timing changes. The timing of major ecological events is often triggered or modulated by seasonal temperature change. Changes in timi ng may already be occurring in the breeding seasons of birds, hibernation seasons of amphi bians, and emergences of butterflies in North America and Europe (Bebee, 1995; Crick et al. , 1997; Brown et al. , 1999; Dunn and Winkler, 1999; Root et al.

, 2003; Roy and Sparks, 2000). Disconnect s in timing of interdependent ecological events may be accompanied by adverse effects on sensitive organisms in the United States. Such effects have already been observed in Europe where forest-breeding birds have been unable to advance their breeding seasons sufficiently to keep up with the earlier emergence of the arboreal caterpillars with which they feed their young. This has resulted in declining productivity and population reductions in at least one species (Both et al. , 2006).

Changes in ecosystem processes. Ecosystem processes, such as nutrient cycling, decomposition, carbon flow, etc., are fundamentally influenced by climate. Climate change is likely to disrupt at least some of these proce sses. While these effects are difficult to quantify, some types of changes can—and have been obser ved. Increasing temperatures over the past few decades on the North Slope of Alaska have re sulted in a summer breakdown of the permanently
frozen soil of the Alaskan Tundra and increased activity by soil bacteria that decompose plant
material. This has accelerated the rate at which CO 2 (a breakdown product of the decomposition of the vegetation and also a gree nhouse gas) is released to th e atmosphere—changing the Tundra from a net sink (absorber) to a net emitter of CO 2 (Oechel et al. , 1993; Oechel et al. , 2000).

Indirect effects of climate change. Climate change may also result in “indirect” ecological effects as it triggers events (the frequency and intensity of fire s, for example) that, in turn,

4 -24SAP 4.6 Chapter 4: Human Welfare

adversely affect ecosystems. In U.S. forest hab itats, increased temperatures are very likely to result in increased frequency and in tensity of wildfires, especially in the arid west, leading to the breakup of contiguous forests into smaller patches, separated by shrub and grass dominated
communities that are more resistant to the effects of fire (Lenihan et al. , 2006). Other major indirect effects are likely to include the loss of coastal habitat through s ea level rise (Warren and Niering, 1993; Ross et al. , 1994; Galbraith et al. , 2002), and the loss of coldwater fish communities (and the recrea tional fishing that they support) as water temperatures increase (Meyer et al. , 1999).

The linkages between these type s of changes and the provisio n of ecosystem services are
difficult to define. W hile ecologists have develo ped a number of metrics of ecosystem condition and functioning ( e.g., species diversity, presence/absen ce of indicator species, primary productivity, nutrient cycli ng rates), these do not ge nerally bear an obvious relation to metrics of
services

. In some cases, such as species diversity and bird population sizes, direct links might be drawn to services (in this case, opportunities for bird watching). However, in many, if not most cases, the linkages between stressor effects, change in ecosystem metrics, and service flows, are more obscure. For example, it is known that fr eshwater wetlands can remove contaminants from surface water (Daily, 1997) and this is an important service. However, the specific ways in which
wetlands do this—in terms of the ecological processes and linkage s within the system—are not well understood, probably vary between different types of wetland ( e.g., beaver swamps vs. cattail stands), and may vary spatially and temporally.

4.3.4.1 Economic Valuation of Effects on Ecosystems
Ecosystems are generally considered non-market goods: although land itself can be bought and sold, there is no m arket for ecosystem services pe r se, and so land value is only a partial measure of the value of the full range of ecosystem services provided. From the perspective of human welfare and climate change, however, we are con cerned less with the ecosystems or the land on which they are located, than with the diverse serv ices they provide, as illustrated in Table 4.4.

Economic valuation of changes in ecosystem serv ices will be easier in cases where there are relationships between ma rket goods and the ecosy stem services being valued. For example, ecosystem changes may result in changes in the av ailability of goods and services that are traded on markets, as in the case of provisioning servic es, such as food, fisheries, pharmaceuticals etc. In other cases, market counterparts to the services may exist, as in the case of regul ating services; for example, insights into the va lue of water purification services can come from looking at the (avoided) cost of a water purification plant to substitute for the ecosystem service. Services, such as water purification, may also have relationships with market goods and services ( e.g., as an input into the production process) that make it po ssible to estimate economic values at least in part or approximately.

Many ecosystem services are, however, truly non-market, in that there are no m arket counterparts by which to estimate their value. Re creational uses of ecosystems fall into this category, and so economists have developed means of inferring values from behavior ( e.g., travel cost), as discussed in the next section), and in other ways. Most of the support services and cultural values of ecosyst ems are also in the “true” non-market category. Value can arise even if

4 -25SAP 4.6 Chapter 4: Human Welfare

a good or service is not exp licitly consumed, or an eco system even experienced. 25 Thus, it can be difficult to define, much less to measure the va lue of changes in these non-market services. To value these services, economists typically use st ated preference (direct valuation) methods, a method that can be used not only for non-market se rvices, but also to va lue services in other categories, such as the value that individua ls place on clean drinking water or swimming
facilities.

Below we report on the relevant literature in two cat egor ies. First, we repo rt on studies that have
looked at the non-market value of specific ecosystems or species . Since only a few of these studies attempt to value the impacts of climate change on ecosystems, we also highlight some non-market studies from the more general litera ture on ecosystem valuation, which can provide insights into the magnitude of potential values of servic es that might be vu lnerable to climate change. Next we look at a diffe rent approach to valuation of ecosystems—a more “top-down” approach—which has been adopted both to look at the effects of climate change and more broadly at the total value of ecosystems

. As the discussions indicate, the treatment of climate change, per se has been very sparse. Moreover, the lack of studies reflects, in part, a need to develop analytical linkages betw een the physical effects of clim ate on ecosystems, the services valued by humans, and appropriate techniques to value changes of the types, and with the breadth, indicated by studies of the eff ects of global change on ecosystems.

4.3.5.2 Valuation of the Effects of Climat e Change on Selected Ecosystem and Species
Although climate change appears in a number of st udies, it is often as a co ntext for the scenario presented in the study for valuation, and so the study cannot be interpre ted as valuation of
climate chan ge or climate effects per se. Only a few studies can be said to value the economic impacts of climate change on a particular ecosystem.

Two studies, Layton and Brown (2000) and Layton and Levine (2003) estima te total values for preventing Colorado (Rocky Mountain) forest loss due to climate change, based on data from the same stated choice or preference survey. The su rvey was conducted with Denver-area residents, who were expected to be familiar with forest ed regions in their nearby mountains. Respondents were given detailed information about climat e change impacts on these forests, including changes in tree line elev ation over both 60-year and 150- year time horizons, and asked to make choices between alternatives, a llowing recovery of implied w illingness to pay (WTP). Layton and Brown (2000) found WTP in the range of $10 to $100 per month, per respondent, to prevent forest loss, with the range depending, in part, on the amount of forest lost. Layton and Levine (2003) reanalyzed the same data set, using a different approach that focuses on understanding respondents’ least preferred, as well as most pr eferred, choices. They f ound that respondents’ value of forest protection depends also on the ti me horizon—preventing eff ects that occur further
into the future are valued less than nearer term effects.

Kinnell et al. (2002) designed and implemented several vers ions of stated pref erence studies that explored the im pacts of wild bird (duck) loss due to ei ther adverse agricultu ral practices, climate

25 Economists have devoted much effort to defining the source of non-market values of ecosystems, coining such terms as “use” and “non-use” value, co nsumption value, existence value, and invoking, as reasons why people care about ecosystesm, the moral philosophies inherent in term s such as stewardship, spir itual values, etc. (see for example, Freeman (2003).

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change, or both. The respondents consisted of Pennsylvania duck hunters, although the hypothetical ecosystem impacts occurred in the Pr airie Pothole region, which is in the northern Midwestern states and parts of Canada. The authors consider ed a hypothetical loss in duck populations, with a scenario that presented some respondents with a 30% loss, and other with a 74% loss, some with a 40 year time horizon, an d others with a 100 year time horizon. The study cannot be viewed as an estimate of willingness to pay to avoid climate change; however, it is interesting because it suggests that recreational enthusiasts ar e willing to pay for ecosystem impacts that they do not necessarily expect to use. In addition, the study provides evidence that the context of climate change or other cause of ecosystem harm (in this case agricultural practices)—irresp ective of the level of harm —may affect respondents’ valuation of the harm.

Although very few studies have valued climate change impacts on ecosystem s, economists have conducted numerous studies (prima rily using direct va luation methods) of eco system values in particular geographic locations , often focusing on charismatic species, or specific types of ecosystems, such as wetlands, in a particular location. In some cases, the estimated values are linked to specific services that the species or ecosystem provide, but in many the services provided are somewhat ambiguous, and it is not always clear what aspect of the species, habitat, or ecosystem is driving the individu al respondent’s economic valuation.

A number of studies indicate that people value the protection of species or ecosystems. Som e of these studies find potentially significant specie s values, ranging from a few dollars to hundreds of dollars per year, per person. For example, MacMillan et al. (2001) estimate the value of restoring woodlands habitat, a nd separately evaluate the reintroduction of the wolf and the beaver to Scottish highlands. In the United States, species such as salmon and spotted owls, as well as their habitat, have been examined in connection to their re spective controversies.

Studies have also looked at th e value of ecosystem s or changes in ecosystems. In the former case, economists use either the value of productive output (harvest) as an i ndicator of value, or respondents value protecting the ecosystem. For ex ample, numerous coastal wetland and beach protection studies have used a variety of non-mark et valuation approaches. A survey of a number of these studies reports values ranging from $198 to approximatel y $1500 per acre (Woodward and Wui, 2001).

Some studies have looked explicitly at the services provided by ecosystems. For example,

Loo mis et al. (2000) consider restoration of several eco system services (dilu tion of wastewater, purification, erosion control, as fish and wildlife habitat, and r ecreation) for a 45-mile section of the Platte River, which runs east from the St ate of Colorado into western Nebraska. Average values are about $21 per month for these addi tional ecosystem services for the in-person
interviewees. While these studies and their values are generally informative, transferring values from studies like the ones above to other ecosystem s, and using the results to estimate values associated with climate change impacts, can be problematic.

4.3.4.3 Top-down Approaches to Valuing the Effects of Climate Change and Ecosystem
Services
From the perspective of deriving values for ecosystem changes (or changes in ecosystem services) associated with climatic changes, one difficulty with the above studies is that the focus

4 -27SAP 4.6 Chapter 4: Human Welfare

is on discrete changes to particul ar species or geographic areas. It is therefore difficult to know how these studies relate to, or shed light on, th e types of widespread and far-reaching changes to ecosystems (and the services they provide) that will result from climate change. Consequently, some studies have attempted to value ecosystems in a more aggr egate or holistic manner. While these studies do not focus specifically on the US, th ey are indicative of an alternative approach that recognizes the interdependence of ecosystem s and their components, and therefore deserve
some discussion.

Several models include values for non-market damages, worldwide, resulting from projected climate change. These impact studies have been conducted at a highly aggregated level; m ost of the models are calibrated using studies of the Unit ed States which are then scaled for application to other regions (Warren et al.

, 2006).

A study of total ecosystem values, but not undertak en in the context of climate change, is the highly publicized study by Costanza et al. (1997), which offers a cont roversial look at valuing
the “en tire biosphere.” Because their reported es timated average value of $33 trillion per year exceeds the global gross national product, economi sts have a difficult time reconciling this estimate with the concept of economic value (WTP); since WTP cannot equal twice income. Ehrlich and Ehrlich (1996) and Pimental et al. (1997) are studies by natura l scientists that have attempted to value ecosystems or in the case of the latter, biodiversity. These are important attempts to indicate the value of ecosystems, but the accuracy and reliability of the values are questionable. To paraphrase a study by several prominent environmental economists that is slightly critical of all of th ese studies, economists do not have any fundamental difference of opinion with these natural scientis ts about the importance of eco systems and biodiversity, rather
it is with the correct use of economic value concepts in these applications (see Bockstael et al.

, 2000).

4.3.5 Recreational Activities and Opportunities
Ecosystems provide humans with a range of services, including outdoor recreational opportunities. In turn, outdoor recreation c ontributes to individua l wellbeing by providing physical and psychological health benefits. In ad dition, tourism is one of the largest econom ic sectors in the world, and it is al so one of the fastest growing (Hamilton and Tol, 2004); the jobs created by recreational tourism provide economic be nefits not only to indi viduals but also to
communities. 26 A number of studies have looked at the qualitative effects of climate change on recreational opportunities ( i.e., resources available) and activitie s in the US, but only a few have taken this literature the additional step of estimating the implications of climate change for visitation days or economic welfare. This section describes the results of this research into the impacts on several forms of recr eation and reports the economic be nefits and losses associated with these changes at the national level.

Slightly more than 90% of the U.S. population participates in some fo rm of outdoor recreation, representing nearly 270 million participants (Cordell et al. , 1999), and several billion days spent each year in a wide variety of outdoor re creation activities. According to Cordell et al. (1999),
the number of people participating in outdoor recreation is highest for walking (67%), visiting a beach or lakeshore or river (62%), sightseeing (56%), swimming (54%) and picnicking (49%).

26 Effects on jobs, income, and similar metrics are cons idered market impacts, an d are not discussed here.

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Most days are spent in activities such as walking, biking, sightseeing, bird-w atching, and wildlife viewing (Cordell et al. , 1999), because of the high number of days per bicycle rider and bird watcher, but the range of outdoor recreation activities in the United States is as diverse as its people and environment. While camping, hunting, backpacking and horseback riding attract a fraction of the people who go biking or bird-watch ing, these other speciali zed activities provide a very high value to their devotees. Many of th ese devotees of specia lized outdoor recreation activities are people who “work to live,” i.e., specialized weekend recreation is one of their
rewards for the 40+ hour workweek.

Climate change resulting from increasing average temperatures as well as changes in precipita tion, weather variability (including more extreme weather ev ents), and sea level rise, has the potential to affect recreation and touris m along two pathways. Figure 4.3 illustrates these direct and indirect effects of climate change on recreation. Since much recreation and tourism occurs out of doors, increased temperature a nd precipitation have a direct effect on the enjoyment of these activities, and on the desired nu mber of visitor days and associated level of visitor spending (as well as tourism employment). Weather conditions are considered one of the four greatest factors influenci ng tourism visitation (Pileus Pr oject, 2007). In addition, much outdoor recreation and tourism depends on the availabi lity and quality of na tural resources (Wall, 1998), Consequently, climate change can also indirectly affect th e outdoor recreational experience by affecting the quality and avai lability of natural resources (and, thus, the availability and quality of recr eational experience) used for recreation such as beaches, forests, wetlands, snow, and wildlife.

Figure 4.3. Direct and Indirect Effects of Climate Change on Recreation

Effects of climate change can be both positive and negative. The length of season for and desirability of several of the m ost popular activ ities—walking, visiting a beach, lakeshore, or river, sightseeing, swimming, and picnicking (Cordell et al. , 1999)—will likely be enhanced by small near- term increases in temperature. Howe ver, long-term higher increases in temperature may eventually have adverse effects on activities like walking, and result in sufficient sea level rise to reduce publicly accessibl e beach areas, just at the time when demand for beach recreation to escape the heat is increasi ng. In contrast, some activities are likely to be unambiguously harmed by even small increase in global warmi ng, such as snow and ice-dependent activities.

In some ways, one can interpret the direct eff ects of climate change as influencing the dem and
for recreation and the indirect effects as influe ncing the supply of r ecreation opportunities. For example, warmer temperatures make whitewater boating more desirable. However, the warmer temperatures may reduce river flows since there is less snowpack, higher evapotranspiration, and greater water diversions for irri gated agriculture. Some studies ci ted below look only at the direct effects, while others represent the combined e ffect of the direct and indirect pathways.

Direct effects. To date, most studies of the direct e ffects of climate change on recreation and
tourism have been qualitative, although a few ha ve been quantitative. Qualitatively, we would expect both positive and negative effects of climat e change on different recreational activities. Many of the qualitative studies rely simply on intu ition to suggest that increases in air and water temperatures will have a positive effect on outdoor recreation visitation in two ways: (a) more enjoyment from the activity; (b) a longer season in which to enj oy the activity (D eFreitas, 2005;

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Scott and Jones, 2005; Scott, Jones and Konopek (2007). Hall and Highman (2005) note that climate change may provide more days of “i deal” temperatures for water- based recreation
activities and some land based recreation activit ies such as camping, picnicking and golf.

The recreational activities most obviously harmed by warmer climate are sports that require snow or cold temperatures, such as downhill and cross country skiing, snowmobiling, ice fishing, and snowshoeing. Reductions in vi sitor use (see, for example, the studies reported in Table 4.5) occur primarily from shorter season, particularly early in the year at such traditional times as Thanksgiving and Spring break. But with warmer temperatures, there is also less precipitation as snow and more as rain on snow, which contribut es to a much shallower snowpack and harder snow. Further, recreating in freezing rain or sl ushy temperatures is not a pleasant experience, reducing benefits from skiing, snowshoei ng, and snowmobiling, further reducing use.

Some recreation areas that are already hot during the summ er recreation season will see decreases in use. For example, the Death Vall ey National Park, Joshua Tree National Park, and
Mesa Verde National Park are all projected to be “intolerably ho t” reducing visitation (Saunders and Easley, 2006).

Most quantitative studies of the effects of climate cha nge on recreation evaluate specific projected changes in temperatur e and/or precipitation, such as a 2.5°C increase in tem perature over the next fifty years. Two quantitative studi es look at effects of temperature change in
Canadian recreation. 27 Scott and Jones (2005) pr oject that the golf season in Banff, Canada could be extended by at least one week and up to ei ght weeks. The combined effect of warmer temperatures lengthening the golfing season, and the increasing the desira bility of golfing during the existing season, together result in an incr ease in the rounds of gol f played by between 50% and 86%. (Similar increases might be expected for golf in northern states of the U.S. such as Minnesota, Wisconsin, New York, etc. with longer golf seasons.) Scott et al. (2006) and Scott and Jones (2005) suggest that some of the previo usly projected large (30% to 50%) reductions in length of ski seasons at northern ski areas ( e.g., in Canada, Michigan, and Vermont) can be reduced (to 5% to 25%) through the use of advanced snowmaking. While use of advanced snowmaking to minimize reductions in ski season seems plausible for the studied northern ski areas, it is doubtful that snowma king would benefit ski areas in California, New Mexico, Oregon and West Virginia where the Thanksgiving and “S pring Break” periods ar e already too warm for successful snowmaking or retention of snow made in some years.

Some studies have used natural vari ations in temperature to ev aluate the effects of climate on recreation (including measures on monthl y, seasonal and inte r-annual variation)

. Two of these
have found that while visitation incr eases with initial increases in temperature, visitation actually decreases as temperature increases even further (Hamilton and Tol, 2004; Loomis and Richardson, 2006). Two of the quantit ative studies, which look not only at visitor days but also at monetary measures of economic welfare, ar e discussed in more detail below, following the
discussion of indirect effects.

27 Scott and Jones (2005) used +1C to +5C in their scenarios and Scott et al. (2006) used +1.5C to +3C in their low impact scenario and +2C to +8C in their high impact scenario.

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Indirect effects. While increased temperature may in crease the demand for some outdoor recreation activities, in some cases climate change may reduce the supply of natural resources on
which those recreational activit ies depend. As noted above, reduced snowpack for winter activities has been projecte d in the Great Lakes (Scott et al. , 2005), in northern Arizona (BarkHodgins and Colby, 2006) and at a representative set of ski areas in the United States (Loomis and Crespi, 1999). 28

For example, lower in-stream flows and lower rese rvoir levels have consistently been shown to
reduce recreation use and benef its (Shaw, 2005). Thus, changes associated with clim ate can reduce opportunities for summer boating and other water sports. When less precipitation falls as snow in the winter, and more falls as rain in the spring, early spring season run-off will increase. Summer river flows will be correspondingly lower, at times when demand for whitewater boating is higher. Human responses to the physical changes associ ated with climate change may
exacerbate natural effects re ducing recreational opportunities. For example, many current reservoirs are not designed to ha ndle huge spring inflows, and thus this water may be “spilled,” which lowers reservoir levels during the summer season. These lower reservoir levels are then drawn down more rapidly as higher temperatur es increase evapotranspiration and increase irrigation releases. In turn, the resulting lower reservoir may leave boat docks, marinas, and boat ramps inaccessible.

Ecosystems that provide recreati onal benefits ma y also be at risk from climate change. Wetlands
are another recreational environment that is at risk fr om climate change. Wetland based
recreation include wild life viewing and waterfowl hunting. With sea level rise, many existing coastal wetlands will be lost, and given existing development inland, these lost wetlands may not be naturally replaced (Wall, 1998 ). The higher temperatures and reduced water availability is also expected to adversely affect freshwater wetlands in the interior of the country. As such waterfowl hunting and w ildlife viewing may be adversely affected.

Higher water temperatures and lower stream fl ows are projected to re duce coldwater trout fisheries (U.S. EPA, 1995; Ahn et al., 2000) as well as native and hatchery stocks of Chinook salmon in the Pacific Northwest (Anderson e t al., 1993). Given trout and Chinook salmon sensitivity to warm water temperatures, thes e affects are not surprising. However, Anderson et al. ’s estimated magnitude of 50% to 100% reduction in Chinook spawning returns is quite large. Reductions of such magnitude will have a substa ntial adverse effect on recreational salmon catch rates, and possibly whether recrea tional fishing would even be allo wed to continue in some areas of the Pacific Northwest. However, from a na tional viewpoint, fishing participation for trout, cool water species and warm water species dom inates geographically sp ecialized fishing like Chinook salmon. Warmer water temperatures are proj ected to eliminate str eam trout fishing in 8-
10 states and result in a 50% reduction in coldwater stream ha bitat in another 11-16 states depending on the GCM model used (U.S. EPA, 1995). This could adversely a ffect up to 25% of U.S. fishing days (Vaughan and Russell, 1982). This 25% loss may be an upper limit as some

28 Higher temperatures (while they increase snowmelt reducin g the snow skiing season) may have two subtle effects: (a) stimulating demand for snow skiing due to warmer temperatures, for those skiers who prefer “spring skiing” due to the warmer temperatures even if the snow conditions are less than ideal; and (b) reduced snowmelt opens up the high mountains for hiking, backpacking and mountain biking activities somewhat earlier than is the case now, which may lead to increases in those visitor use days.

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coldwater stream anglers may substitute to less a ffected coldwater lakes/reservoirs or switch to cool/warm-water species such as bass (U.S. EPA, 1995)

. Studies that be tter account for substitution effects, such as Ahn et al. (2000), indicate a 2-20% drop in benefits of trout fishing depending on the projected degrees of temperatur e increase which ranged from 1°C to 5°C.

Sea level rise reducing beach area and beach erosi on are concerns with climate change that m ay make it difficult to accommodate the incr eased demand for beach recreation (Yohe et al. , 1999). In the near term, recreational forests may also be adversely affected by climate change. Although forests may slowly migrate northward and into hi gher elevations, in the short run there may be dieback of forests at the current forest edges (a s these areas become too hot), resulting in a loss of forests for recreation. In the long term, howev er, several analyses s uggest forest species composition and migration due as well as net in creases in forest ar ea due to carbon dioxide fertilization (Joyce et al., 2001; Iverson and Matthews, 2007). Thus, eventually there may be resurgence in forest recreation.

Saunders and Easley (2006) find that natural re sources of ma ny western National Parks, National Recreation Areas, and National Mo numents resources will be a dversely affected by climate change. The most common adverse effects are re ductions in some wildlife species, loss of coldwater fishing opportunities and increasing park closures due to wildfire associated with stressed and dying forest stands. The text box discusses in more de tail potential eff ects of climate change on one park: Rocky Mountain National Park, which has been the subject of both ecological and economic analysis.

4.3.5.1 Economic Studies of Effects of Climat e on Recreation
Changes in economic welfare due to the effects of climate change on non-market resources, such as recreation, can be evaluated in several ways . F irst, since decisions regarding recreational activities depend on both direct and indirect effects of climate, changes in human well-being (as a result of these changes) will be reflected in changes in visitor use. Social scientists believe changes in visitor use are motivated by people “v oting with their feet” to maintain or improve their well-being. In the face of higher temperatures, people may seek relief, for example, by visiting the beach or water skiing at reservoirs more frequently to cool down. Similarly, reduced opportunities for recreation due to indirect effects of climate change will also be reflected in reduced visitation days. Thus, one metric of effects on human well-being is the change in visitation days.

Second, recreational trips—for example, to rese rvoirs and beaches—have economic implications
to the visitor and the econom y. Visitors allocate more of their scarce time and household budgets
to the recreational activities that are now more preferred in a warmer climate. This reflects their “willingness to pay” for these recr eational activities, which is a m onetary measure of the benefits they receive from the activity. Numerous economic studies provide estimates of the value of changes in diverse recreational activities, usi ng various economic techni ques (such as travel

cost 29 analysis and stated preference methods) (see Section 3 of this chapter and the chapter Appendix for more information). While these studies typically do not focus directly on climate

29 The travel cost method traces out a demand curve for recr eation using travel cost as proxies for the price of recreation, along with the corresponding number of trips indi vidual visitors take at th ese travel costs. From the demand curve, the net willingness to pay or consumer surplus is calculated

.

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change, they can be used to extract values for the types of changes that are projected to be associated with climate change.

Third, some people who do not currently visit un ique natural environments m ay value climate stabilization policies that preserve these natura l environments for future visitation. These people have what economists call a value for preservi ng their option—their ability— to visit the environments in the future (Bishop, 1982). This option value is much like purchasing trip insurance to guarantee that if one wanted to go in the future, that conditions would be as they are today

.

As discussed below, economists have available a numb er of well-studied and techniques to evaluate the impacts of climate change on at l east some of the recreat ional service provided by
ecosystems

. However, only a few studies have looked expl icitly at the effects of climate change
on recreation in the US

. More research is needed to unders tand the linkages between weather and recreation, and to extrap olate results to the range of recr eational activities throughout the US.

Change in visitation days. Two studies (Loomis and Crespi, 1999; Mendelsohn and Markowski, 1999) have examined the eff ects of clim ate on r ecreational opportunities comprehensively for the entire US. These stud ies both examined the effects of 2.5°C and 5°C increases in temperature, along with a 7% increase in precipitation. The studies used similar methodologies to estimate visitor days for a range of recreational opportunities. Each study looked at slightly different effects, but between them examined a mix of direct and indirect climate effects, including direct effects of higher temperatures on golf and beach recreation visitor days, and indirect effects of snow c over on skiing. Both studies estimate changes in visitation days due to climate change, and then us e the results of a number of economic valuation studies to place monetary values on the visitation days. The studies find that, as expected, nearterm climate change will increase participation in activities such as wa ter-based recreation, and reduce participation in snow sports.

Table 4.5 presents the results of the two studies. The results s uggest that relatively high participation recreation activ ities such as beach and stream recreation gai n, and low participation activities like snow skiing lose. Although the percentage drop in vi sitor days of snow sports is much larger than the percentage increase in vi sitor days in water-base d recreation, the larger number of water-based sports pa rticipants more than offsets the loss in the low participation snow sports. Thus, on net, there is an overall ne t gain in visitation associated with the assumed increases of 2.5°C in temperat ure and 7% in precipitation. 30

The methods used to forecast visitation were s lightly differen t between the two studies. To estimate visitor days for all recreation activit ies, Mendelsohn and Markowski regressed state level data on visitation by recr eation activity as a f unction of land area, water area, population, monthly temperature and monthl y precipitation. The Loomis and Crespi study used a similar

30 Geographic regions within the U.S. will experience different gains and losse s. Currently hot areas with less access to water resources ( e.g., New Mexico) may suffer net overall reductions in recreation use to due higher heat that makes walking, sightseeing, and picnicking less desirable. St ates with substantial water resources (lakes, seashores) may gain visitor days and tourism. Currently cold areas such as the Dakotas and New York may see increases in some recreation due to longer summer seasons.

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approach to Mendelsohhn and Markowski for some activities, such as golf. Other forecasting techniques were used for other activities; for ex ample, for beach recreation, they used detailed
data on to individual beaches in the Northeas tern, Southern and West ern United States to estimate three regional regression equations to pr oject beach use, and the response of reservoir recreation to climate change was analyzed usi ng visitation at U.S. Ar my Corps of Engineers
reservoirs.

For some of the recreatio nal activities, the Loomis and Crespi study included indirect, as well as direct, effects. For example, th e reservoir m odels incorporated climate-induced reductions in reservoir surface area besides temperature and pr ecipitation. Similarly, the estimate of visitor days for snow skiing used projected changes in the number of days of minimum snow cover to adjust skier days proportionally. In some cases, only indirect (s upply) effects were included, as in the case of stream recreation, water fowl hunting, bird viewing and forest recreation. Since these estimates do not include changes in visitation associated with direct effects of climate we
have less confidence in the accur acy of these results, than we do for reservoir recreation which
takes into account both demand and supply effects on recreation use.

Valuation of gains and losses in visitor days . Since different activities may have different levels of enjoyment provided to the visitor (a nd, therefore, dif ferent economic values), adding up changes in visitation days to produce a “net ch ange” is not an accurate representation of the overall change in well-being. The two studies di scussed above used net willingness to pay as a measure of value of each day of recreation (Section 3 of this chap ter provides a discussion of the concept of willingness to pay as a common eco nomic measure of changes in welfare).

To date there have been few original or primar y valuation studies of climate change per se on recreation; the case study on Rocky Mountain N ati onal Park presented below provides one of the few examples. Other studies include Scott a nd Jones (2005), which focused on Banff National Park, Scott et al. (2006), which looked at snow skiing, Scott et al. (2007), which focused on Waterton National Parks, and Pendleton and Me ndelsohn (1998), which estimated values for fishing in the northeastern US. 31 There have, however, been hundreds of recreation valuation studies; the values from these studies (generally tr avel cost or stated preference) can be applied to other applications using a “benefit transfer” approach, a nd applying average values of recreation from previous studies to value their respective visitor days.

Loomis and Crespi (1999) and Mendelsohn and Markowski (1999) estimat e the overall net gain in visitor benefits, using the change in visitor days reported in Table 4.5 and estim ated values of a visitation day reported in the literature. L oomis and Crespi (1999) adopt a disaggregated activity approach, and Mendelsohn and Markow ski (1999) apply a state level approach. 32 Both

31 The three papers by Scott are discussed elsewhere in th is paper. Pendleton and Mendelsohn use a random utility model of recreational fishing in the northeastern U.S. They find that, while catch rates of rainbow trout would decrease, catch rates of other trout and pan fish would increase. On net, recreational fishing benefits (under a climate
scenario associated with a doubling of atmospheric CO 2 concentrations) are reduced in the state of New York, but there are offsetting gains in more northern states like Maine.

32 As noted above, Mendelsohn and Markowski (1999) used state level regression modeling to estimate effects on all activities. In contrast, Loomis and Crespi (1999), used diff erent regression models and different geographic scales for different recreation activities to take advantage of the more micro-level datasets available for beach and reservoir
recreation.

4 -34SAP 4.6 Chapter 4: Human Welfare

of these studies find that temperature increase s of 5°C and up result in increased benefits. However, as noted below, the case study of Roc ky Mountain National Park suggests that extreme heat is likely (based on the model results) to cause these visitor benefits to decrease at some point.

Visitors are somewhat adaptable to climate chan ge in the recreation ac tivities they ch oose and when they choose them. Thus, recreation represen ts one situation with opportunities to reduce the adverse impacts of climate change, or incr ease its benefits, via adaptation. As noted by Hamilton and Tol (2004), warmer temperatures ma y shift visitors northward, and up into the mountains. Thus currently cool areas ( e.g., Maine, Minnesota, Washingt on) may gain, and warm areas ( e.g., Florida, Arizona) may lose, tourism.

Some adaptive responses can be expensive, a nd ma y be of limited effectiveness; such as snowmaking at night, which is often mentione d as an adaptation for downhill skiing (Irland et al. , 2001). Other adaptive behavior may include moving some outdoor recreation activities indoors. For example, bouldering is now taking place in climbing gyms on artificial climbing walls. Running on a treadmill in an air conditioned gym may be a substitute for running out of doors for some people, but casual observation s uggests that many people pr efer to run out doors when weather permits. Unless preferences adjust to increased temperatures, there may be a loss in human well-being from substituting the treadm ill in the air conditioned gym for the out of
doors

. Box 4.2 summarizes a case study of the impacts of climate change on Rocky Mountain
National Park

.
4.3.6 Amenity Value of Climate
It is well established that preferences for climat e affect where people choose to live and work. The desire to live in a mild, sunny climate m ay reflect health considerations. For example, people with chronic obstructive l ung disease or angina may wish to avoid cold winters. Warmer climates may be more pleasant for persons with arthritis. Climate preferences may also reflect the desire to reduce heating and/ or cooling costs. Certain climates may be complementary to leisure activities. For example, sk iers may wish to live in colder climates, sunbathers in warmer ones. Or a particular climate may simply make life more enjoyable in the course of everyday life. We would also expect based on the evidence that, in addition to preferri ng certain temperatures and more sunshine, people would prefer to reduce the risk of e xperiencing abrupt climate events
such as hurricanes and floods.

While climate itself is not bought and sold in ma rkets, the goods that ar e integral to location decisions—such as housing and jobs— are ma rket goods. Consequently, economists look at behavior with regard to location choice (the prices that are paid for houses and the wages that are accepted for jobs) in order to determine how larg e a role climate plays in these decisions and, therefore, how valuable different climates are to the general public. The re mainder of this section
discusses methods that have been used to estima te the amenity values people attach to various climate attributes, as well as the value they attach to a voiding extreme weather events. Unfortunately, few studies have rigorous ly estimated climate amenity values ( e.g., the value of a 2°C change in mean January temperature) for th e United States and then used these values to
estimate the dollar value of va rious climate scenarios.

4 -35SAP 4.6 Chapter 4: Human Welfare

4.3.6.1 Valuing Climate Amenities
People’s preferences for climate at tributes should be reflected in their location decisions. Other things equal, homeowners should be willing to pay more for housing (and so bid up housing prices) in more desirable climates, and so prope rty values should be higher in those climates. Similarly, workers should be willing to accept lowe r wages to live in more pleasant climates; if climate also affects firms’ costs, however, actual wages may rise or fall due to the interaction between firms and workers (Roback, 1982).

Early attempts to estimate how much consumers will pay for more desirable climates start from the view that a good—such as housing or a job—is a bundle of attributes that are valued by the
homeowner or worker. T he price the consumer pays for the good (such as a house) is actually a composite of the prices that are implicitly paid for all the attributes of the good. Using a statistical technique (known as a hedonic value function), economists can estimate the price of a particular attribute, such as climate. The hedonic property value func tion, thus, describes how housing prices vary across cities as a function of housing characteristics and locational amenities, such as climate, crime, air quality, or proxi mity to the ocean. Similarly, the hedonic wage function relates the observed wage s to job characteristics (such as occupation and industry), worker characteristics (such as education and years of experien ce), and locational amenities.

The value of locational amenities— i.e., how m uch individuals are willing to pay for amenities— can be inferred from these estimated hedonic wage and property value functions. Extracting this value, however, assumes that workers and homeowners are mobile, i.e., that they can choose where to live fairly freely within the United States. Similarly, it assumes that, in general,
individuals have moved to where they would like to liv e (at the moment), so that housing and job markets are in what is said to be “equilibrium .” It also assumes that workers and homeowners have good information about the location to whic h they are moving, and that sufficient options (in terms of jobs and houses and amenities) are ava ilable to them. The estimates of the value of a particular amenity—such as climate—will be more accurate the more nearly these assumptions

are met.

A number of hedonic wage and property value studies have included climate, a mong other variables, in their an alyses: by Hoch and Drake (1974); Cr opper and Arriaga-Salinas (1980); Cropper (1981); Roback (1982); Smith (1983); Blomquist et al. (1988); Gyourko and Tracy (1991). The first four studies estimate only hedoni c wage functions, while the last three estimate both wage and property value equations. As M oore (1998) and Gyourko and Tracy (1991) note, this literature suggests that climate amenities are reflected to a greater extent in wages than in property values. 33 Roback (1982), Smith (1983), and Blomquist et al. (1988) all find sunshine to be capitalized in wages as an amenity, while heat ing degree days are capitalized as a disamenity (Roback, 1982, 1988; Gyourko and Tracy, 1991).

33 The effect of weather variables on property values is mixed, with Blomquist et al. (1988) finding property values to be negatively correlated with precipitation, humidity and heating and cooling degree days, but Roback (1982) finding property values positively correlated with heating degree days. Gyourko and Tracy (1991) find heating and cooling degree days negatively correlated with hou sing expenditures, but humidity positively correlated.

4 -36SAP 4.6 Chapter 4: Human Welfare

More recent studies using the hedonic approach include Moore (1998) and Mendelsohn (2001),
who use their results to estimate the value of mean temperature changes in the United States
associated with future climate scenarios. M oore uses aggregate wage data for Metropolitan Statistical Areas (MSAs) to estimate the res ponsiveness of wages with respect to climate variables for various occupations. Climate is cap tured by annual temperature, precipitation and by the difference between average July and averag e January temperature. Moore estimates that a
4.5 ◦ C increase in mean annual temperature would be worth between $30 and $100 billion (1987$) assuming that precipitati on and seasonal variation in te mperature remain unchanged.

Mendelsohn (2001) uses county-level data on wages and rents to estimate hedonic wage and property value models. Separate equations are estim ated for wages in retail, wholesale, service
and m anufacturing jobs. Climate variables, wh ich include average January, April, June and October temperature and precipitation, enter each equation in quadratic form. Warmer temperatures are generally associated with lo wer wages and lower rent s, although the former effect is larger in magnitude. Me ndelsohn uses the results of these models to estimate the impact of a uniform increase in temperat ure of 1°C, 2°C and 3.5°C, paire d, alternately with an 8% and a 15% increase in precipitation. The results sugges t that warming produces positive benefits in every scenario except the 3.5°C temperature chan ge. Averaging across estimates produced by the 3 models for each of the 6 scenarios suggests annual net benefits (in 1987$) of $25 billion.

Unfortunately, hedonic wage and pr operty value studies have limitations that have caused them to be replaced by alternate approaches to analyz ing data on location choi ces. One drawback of the hedonic approach is that, as mentioned a bove, it assumes that national labor and housing markets exist and are in equilibrium. As Graves and Mueser (1993) and Greenwood et al. (1991) point out, if national markets are not in equilibrium, inferring the va lue of climate amenities from hedonic wage and property value st udies can lead to badly biased results. A second problem is that variables that are correlated with climate ( e.g., the availability of recreational facilities) may be difficult to measure; hence, climate variable s may pick up their eff ects. In hedonic property value studies, for example, the use of heati ng and cooling degree days to measure climate amenities is problematic because their coefficien ts may capture differences in construction and energy costs as well as climate amenities per se. A related problem in hedonic wage equations is that more able workers may locate in areas with more desirable climat es. If ability is not adequately captured in the hedonic wage equati on, the coefficients of climate amenities will reflect worker ability as well as the value of climate.

Cragg and Kahn (1997) were the fi rst to relax the national land and labor ma rket equilibrium assumption by estimating a discrete location choi ce model. Using Census data, they model the location decisions of people in the United States who moved betw een 1975 and 1980. Movers compare the utility they would receive from living in different states—which depends on the wage they would earn and on the cost of housing, as well as on climate amenities—and are assumed to choose the state that yields the hi ghest utility. This allows Cragg and Kahn to estimate the parameters of individua ls’ utility functions and thus infe r the rate at which they will
trade income for climate amenities.

The drawback of this study is that it estimates the preferences of move rs, who m ay differ from the general population. An a lternate approach (Bayer et al. , 2006; Bayer and Timmins, 2005) is

4 -37SAP 4.6 Chapter 4: Human Welfare

to acknowledge that moving is costly and to ex plain the location decisions of all households, assuming that all households are in equilibrium, given moving costs. Unfortunately, the discrete choice literature has yet to provide reliable estimates of the value of climate amenities in the
United States.

4.3.6.2 Valuing Hurricanes, Fl oods, and Extreme Weather Events
It is sometimes suggested that the value people place on avoi ding extreme weather events can be measured by the damages that such events cause, or by the premiums that people pay for flood or
disaster insurance. Ex post losses associated with extreme weather events represent a lower bound to the value people place on avoiding these even ts, as long as people are risk averse. It is also the case that people can purchase insurance only against the monetary losses associated with floods and hurricanes; hence, insurance premiu ms will not capture the entire value placed on avoiding these events.

The value of avoiding extreme weather events sh ould be reflected in property values, assumi ng that people are informed about risks: houses in an area with high probability of hurricane damage should sell for less than comparable houses in an area with a lower chance of hurricane damage, holding other amenities constant. To estimate the value of avoiding these events correctly is, however, tricky; it can be difficult, for example, to disentangle hurricane ri sk (a negative effect) from proximity to the coast (an amenity).

Recent studies use natural experiments to determ ine the value of avoiding hurricanes and floods.
Hallstrom a nd Smith (2005) use property value da ta before and after hur ricane Andrew in Lee County, Florida, a county that did not suffer dama ge from the hurricane, to determine the impact of people’s perceptions of hurricane risk on prop erty values. They find that property values in special flood hazard areas of Lee County d eclined by 19% after hurricane Andrew. The magnitude of this decline is significant, and agrees with Bin and Polasky (2004). Bin and Polasky find that housing values in a flood plain in North Carolina declined significantly after hurricane Floyd, compared to houses not at ris k. For the average house, the decline in price exceeded the present value of premiums for flood insurance, suggesting that the latter are, indeed, a lower bound to the value of avoiding floods.



### 4.4 Conclusions

The study of the impacts of climate change on human welfare, well-being, a nd quality of life, is still developing. Many studies of impacts on partic ular sectors—such as health or agriculture— discuss, and in some cases quantify, effects that ha ve clear implications for welfare. Studies also hint at changes that are perhap s less obvious, but also have welfar e implications (such as changes in outdoor activity levels and how much time is spent indoors) and point also to effects with far more dramatic consequences (such as breakdown in public services and infr astructure associated with possible extreme events of the magnitude of Katrina) . Adaptation, too, has welfare implications that studies do not al ways point out, such as the co sts (financial and psychological) to the individual of changing behavior.

To our knowledge, no study has made a systematic su rvey of the my riad welfare implications of climate change, much less attempted to quan tify—nor yet to aggreg ate—them. An almost

4 -38SAP 4.6 Chapter 4: Human Welfare

bewildering choice of typologies is available for categorizing effects on quality of life, wellbeing, or human welfare

. The social science and planning liter atures provide not only a range of typologies, but also an array of metrics that could be used to measure life quality.

This chapter explores one commonly used method: the social indicators a pproach. This approach generally divides lif e quality effects into broad categories, such as economic conditions or human health, and then identifies sub categories of important effects.

Most of the measures of we ll-being —including the social indicators approach—focus on
individual measures of well-b eing, although measured at the soci ety level. There is, however, another dimension to well-being—community we lfare. Communities represent networks of households, businesses, physical structures, and in stitutions and so reflect the interdependencies and complex reality of human systems. Unde rstanding how climate impacts communities, and
how communities are vulnerable—or can be made more resilient—in the face of climate change, is an important component of unders tanding well-being and quality of life

.

Economics offers one alternative to address the diversity of impacts: valuing welfare impacts in monetary terms, which can then be summ ed. Estimating value, however, requires completing a series of links—from projected climate change to quantitative measures of effects on commodities, services, or conditions that are link ed to well-being, and then valuing those effects using economic techniques.

Regardless of the framework, estimating impact s on human well-being involves num erous and
diverse effects

. This poses several critical difficulties:

 The large number of effects m akes the task of linking impacts to climate change— whether qualitatively or quantitatively—difficult.

 The interdependence of physical and huma n sy stems further complicat es the process of quantification—both for community effects, and also for ecosystems, raising doubts about a piecemeal approach to estimation.

 The diversity of effects raises questions of how to aggregate effects in order to develop a composite m easure of well-being or other metr ics that can be used for policy purposes.



### 4.5 Expanding the Knowledge Base

Despite the potential for imp acts on human well-being, little research focuses directly on understanding the relationship between well-bei ng and climate change. Completely cataloging the effects of global change on human well-being or welfare would be an immense undertaking, and no well-accepted structure for doing so has been developed and applied. Moreover, identifying the potentially lengthy list of climate-rela ted changes in lifestyle, as well as in other, more tangible, features of well-being (such as income), is itself a daunting task—and may includes changes that are not easily captured by ob jective measures of well-being or quality of
life.

This chapter has looked at the climate impacts a nd economics literature in four areas of welfare
effects—hum an health, ecosystems, recreati on, and climate amenities. For each of the non4 -39SAP 4.6 Chapter 4: Human Welfare

market effects analyzed here, sign ificant data gaps exist at each of the steps necessary to provide monetized values of climate impacts

. Although the economics literature for only a few areas of effects is examined, it is probable that similar in formation gaps exist for the valuation of other impacts of climate change, partic ularly those that involve non-ma rket effects (see Table 4.1). In addition, economic welfare—as with any other aggregative approach—d oes not adequately address the question of how to deal with effects which may not be amenable to valuation or with interdependencies among effects and systems

.

Developing an understanding of the impacts of climate change on hum an welfare may require taking the following steps:

 Develop a frame work for addr essing individual and commun ity welfare and well-being, including defining welfare/we ll-being for climate analysis and systematically categorizing and identifying impacts on welfare/well-being

 Identify priority categories for data collec tion and research, in order to establish and quantify the linkage fro m climate to welfare effects

 Decide which me trics should be used for these categorie s; more generally, which components of welfare/well-being should be m easured in natural or physical units, and
which should be monetized

 Investigate me thods by which diverse metrics ca n be aggregated into a synthetic indicator ( e.g., vulnerability to climate change impacts, in cluding drought, sea level rise, etc.), or at least weighted and compared in policy d ecisions where aggregation is impossible

 Develop an approach for addressing those welfar e effects that are diffi cult to look at in a piecemeal way, such as welfare cha nges on communities or ecosystems.

 Identify appropriate top-down and bottom- up approaches for estim ating impacts and value (whether economic or otherwise) of the most critical welfare categories.

 Identify situations in which evaluation fo llowing the above steps is likely to be prohibitively difficult, and determining altern ative methods for appr oaching the topic of the impact of global change on well-being.

Together, these steps should enable research ers to ma ke progress towards promoting the consistency and coordination in analyses of welf are/well-being that will facilitate developing the body of research necessary to analyze impacts on hu man welfare, well-being, and quality of life.

4 -40SAP 4.6 Chapter 4: Human Welfare



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### 4.7 Appendix 1 

## : Chapter 4 : Human Welfare Economic Valuation: An Introduction to Techniques and Challenges

Assessments of the benefits and costs, whethe r explicit or tacit, underlie all discussion and
debates over alternative actions regarding climat e change. These assessments are frequently used to inform such questions as: What actions are ju stified to ease adaptati on to changing climate? Or how much are we willing to pay to redu ce emissions? (Jacoby, 2004). Ideally, such analyses would be undertaken with complete and reliab le information on benefits, converted into a common unit, commensurable with costs and with each other (Jacoby, 2004)

. In reality, however, while many impacts can be valued, some linkages from climate change to welfare effects are difficult to quantify, much less value. This appendix describes the steps in developing a benefits estimate, and the tools that economists have available for monetizing benefits. It also briefly discusses some of the challenges in monetizing benefits, and weakne sses in the approach.

Estimating the Effects of Climate Change
The process of estimating the effects of climat e change, including effects on huma n welfare, involves up to four steps, illustrated in Figur e 4A.1. Moving down from the top of Figure 4A.1, the gray area occupies a larger portion of each box, indicating (in rough terms) that at each stage
it is more and more difficult to de velop quantified, rather than qualitative, results. The first step is to estimate the change in re levant measures of climate, in cluding temperature, precipitation, sea-level rise, and the frequency and severity of extreme events

. This step is usually accomplished by atmospheric scientists - some form of global circulation model (GCM) is typically deployed

. Some analyses stop after this step.

The second step involves estimating the physical e ffects of those changes in climate in term s of qualitative changes in human and natural systems

. These might include changes in ecosystem structure and function, human expos ures to heat stress, change s in the geographic range of disease vectors, melting of snow on ski slopes, or flooding of coastal areas

. A wide range of disciplines might be involved in carrying out those analyses, depl oying an equally wide range of
tools

. Many analyses are complete once this step is completed - for example, we may be unable to say anything more than that increases in pr ecipitation will change an ecosystem's function.

The third step involves transla ting the physical effects of chan ges in climate into m etrics indicating quantitative impacts

. If the ultimate goal is moneti zation, ideally these measures
should be amenable to valuation

. Examples include quantifying the number and location of properties that are vulnerable to floods, estimating the number of individuals exposed to and sensitive to heat stress, or esti mating the effect of diminished migratory bird populations on birdwatching participation rates

. Many analyses that reach this step in the process, but not all, also proceed on to the fourth step.

The fourth step involves valu ing or monetizing the changes

. T he simplest approach would be to apply a unit valuation approach; for example, the co st of treating a nonfatal case of heat stress or malaria attributable to climate change is a firs t approximation of the value of avoiding that case altogether

. In many contexts, however, uni t values can misrepresent the true marginal economic

4 -57SAP 4.6 Chapter 4: Human Welfare

impact of these changes

. For example, if climate change re duces the length of the ski season, individuals could engage in another recreationa l activity, such as golf

. Whether they might prefer skiing to golf at that time a nd location is something economists might try to measure.

Figure 4A.1 Estimating the Effects of Climate Change

Step 1 : Estimate Climate Change (magnitude & timing)

• Temperature • Precipitation
• Sea-level rise
• Extreme weather events

Non-quantified physical effects

Impacts that can not be quantified

Impacts that can not be monetized Step 2 : Estimate Physical Effects (spatial & temporal distribution)

• Human exposure to heat stress • Change in ecosystem structure and
function • Arial extent of flooding • Timing of snow melt

• Man y more...

Step 3 : Estimate Quantitative Impacts

• Number of sick individuals • Changes in recreationa l participation rates • Property losses • Change in species populations • Many more...

Step 4 : Value or “Monetize” Effects

• Lost property value
• Cost of illness
• Loss in recreational “use value”
• Loss of human welfare for other effects

This step-by-step linear approach to effect s estimation is sometimes called the "damage function" approach

. One practical advantage of the damage function approach is the separation of disciplines—scientists can complete their work in steps 1 and 2, and sometimes in step 3, and then economists do their work in step 4

. The linear process can work well in cases where individuals respond and change th eir behavior in response to ch anges in their environment, without any "feedback" loop

.

The linear approach is not always appropriate, however

. A damage function approach might imply that we look at effects of climate on hum an health as separate and independent from effects on ecology and recreation, but at some leve l they are inter-relate d, as health care and

4 -58SAP 4.6 Chapter 4: Human Welfare

recreation both require resources in the form of income

. In addition, responding to heat stress by installing air conditioning leads to higher energy demand, which in turn may increase greenhouse gas emissions and therefore contribute to further climate change

. Recent research suggests that the damage function approach, under some cond itions, may be both overly simplistic (Freeman, 2003) and subject to serious errors (Strzepek et al. , 1999; Strzepek and Smith, 1995)

.
Monetizing and Valuing Non-Market Goods
Economists have developed a suite of methods to estimate willingness to pay for non-m arket goods (see text for a discussion of th e market vs. non-market distinction)

. These methods can be grouped into two broad categories, based largely on the source of the data: revealed preference and stated preference approaches (Freeman, 2003; U.S. EPA, 2000)

. Revealed preference,
sometimes referred to as the indirect valuation approach, involves infe rring the value of a nonmarket good using data from market transactions

. For example, a lake may be valued for its ability to provide a good fishing experience. This value can be estimated by the time and money expended by the angler to fish at that particular site, relative to all ot her possible fishing sites

. Or, the amenity value of a coastal property that is pr otected from storm damage (by a dune, perhaps) can be estimated by comparing the price of that property to other properties similar in every way but the enhanced storm protection

.
Stated And Revealed Preference Approaches
Accurate measurement of the non-market amenity of interest, in a ma nner that is not inconsistent with the way market participants perceive the amenit y, is critical to a robust estimate of value.

Revealed preference approaches include recreational de m and models, which estimate the value of recreational amenities through time and mone y expenditures to enj oy recreation; hedonic wage and hedonic property value models, which a ttempt to isolate the value of particular amenities of property and jobs not themselves dir ectly traded in the marketplace based on their price or wage outcomes; and averting behavior models, which estimate the value of time or money expended to avert a particular bad outcome as a measure of its negative effect on welfare.

Stated preference approaches, some times referred to as direct valuation approaches, are survey
methods that estimate the value individuals place on particular non-market goods based on choices they make in hypothetical markets. 34 The earliest stated pref erence studies involved simply asking individuals what they would be willing to pay for a particular non-market good

. The best studies involve great care in constr ucting a credible, though still hypothetical, trade-off between money and the non-market good of interest to discern individual preferences for that good and hence, willingness to pay (WTP)

. For example, economists might construct a hypothetical choice between multiple housing lo cations, each of which differs along the dimensions of price and health risk

. Repeated choice experiments of this type ultimately map out
the individual’s tradeoff betw een money and the non-market good

. The major challenges in stated preference methods involve study design, pa rticularly the construc tion of a reasonable and credible market for the good, and estimation of a valuation function fr om the response data

.

34 The contingent valuation method (CVM), or a modern variants, a stated choice model (SCM), are forms of the stated preference methods.

4 -59SAP 4.6 Chapter 4: Human Welfare

In theory, if individuals understa nd the full implications of thei r market choices, in real or constructed markets, then both revealed and st ated preference approaches are capable of providing robust estimates of the total valu e of non-market goods. When considering the complex and multidimensional implications of climat e change in the application of revealed and stated preference approaches, it can be extraordin arily challenging to ensure that individuals are sufficiently informed that their observed or stat ed choices truly reflect their preferences for a particular outcome

. As a result, these methods are most often applied to a narrowly defined nonmarket good, rather than to a complex bundle of non-market goods that might involve multiple tradeoffs and synergistic or antagonistic eff ects that would be difficult to disentangle.

In addition to market or non-mark et goods that reflect some use of the environment, value can arise even if a good or service is not e xplicitly consumed, or even experienced

. For example, very few individuals would value a polar bear for its ability to provide sustenance - those who do might not express that value th rough a direct market for polar bear meat, but by hunting for the
bear

. Whether through a market or in a non-market activity, those individuals have value for a consumptive use—once enjoyed, that good is no longer available to others to enjoy

. In addition to the consumptive users, a small but somewhat la rger number of individuals might travel to the Arctic to see a polar bear in its natural environment

. These individuals might express a value for polar bears, and their "use" of the bear is non-co nsumptive, but in some sense it does nonetheless affect others’ ability to view the bear—if too ma ny individuals attempt to view the bears, the congestion might cause the bears to become frig htened or, worse, domesticated, diminishing the experience of viewing them.

A third, perhaps much larger group of individuals will ne ver travel to see a polar bear in the
flesh

. But many individuals in this group would expe rience some diminishment in their overall quality of life if they knew that polar bears had become extinct

. This concept is called " non-use value "

. Although there are severa l categories of non-use value - so me individuals may wish to preserve the future option to visit the Arctic and see a bear, others to bequeath a world with polar bears to future generations, and others might valu e the mere existence of the bears out of a sense of environmental stewardship

. While not all economists agree that non-use values ought to be relevant to policy decisions (Diamond and Haus man, 1993), there is broad agreement that they are difficult to measure, because the expression of non-use values does not result in measurable economic behavior (that is, there is no "use" expressed)

. Those that recognize non-use values acknowledge that they are likely to be of greatest consequence where a resource has a uniqueness or “specialness” and loss or injury is irreversible, for example in the global or local extinction of a species, or the distribution of a unique ecological resource (Freeman, 2003).

Other Methods of Monetizing
Analysts can employ other non-mark et valuation me thods: avoided co st or replacement cost, and input value estimates. These methods do not measur e willingness to pay as defined in welfare economic terms, but because the methods are relatively straightforward to apply and the results often have a known relationship to willingness to pay, they provide insights into non-market values. This chapter focuses on willingness to pa y measures, but recognizes that alternative methods may provide insights and sometimes be more manageable (or appropriate) to estimate a particular non-market value, given data cons traints and the limitations imposed by available
methods.

4 -60SAP 4.6 Chapter 4: Human Welfare

Cost of illness studies estimate the change in health e xpenditures resulting from the change in incidence of a given illness

. Direct costs of illness include cost s for hospitalization, doctors’ fees, and medicine, among others

. Indirect costs of illness include eff ects such as lost work and leisure
time

. Complete cost of illness estimates re flect both direct and indirect costs

. Even the most complete cost of illness estimates, however, t ypically underestimate willingness to pay to avoid incidence of illness, because they ignore the loss of welfare associated with pain and suffering and may not reflect costs of av erting behaviors the individuals have taken to avoid the illness

. Some studies suggest that the difference between cost of il lness and willingness to pay can be large, but the difference varies greatly across health effects and individuals (U.S. EPA, 2000).

Replacement cost studies approach non-ma rket values by estimating the cost to replace the services provided to individuals by the non-market good

. For example, healthy coastal wetlands may provide a wide range of services to indi viduals who live near them; they may filter pollutants present in water; absorb water in time s of flood; act as a buffer to protect properties from storm surges; provide nursery habitat fo r recreational and commercial fish; and provide amenities in the form of oppor tunities to view wildlife

. A replacement cost approach would estimate the value of these services by estim ating market costs for treating contaminants, containing floods, providing fish fr om hatcheries, or perhaps rest oring an impaired wetland to
health

.

The replacement cost approach is limited in th ree important ways: 1) the cost of replacing a resource does not necessarily bear an y relation to the welfare enhanc ing effect of the resource; 2) as resources grow scarce, we would expect their value would be underestimated by an average replacement cost; 3) Complete replacement of ecological systems and services may be highly problematic

. Replacement cost studies are most informative in those conditions where loss of the resource would certainly and without exception tr igger the incidence of replacement costs - in reality, those conditions are not as common as they might seem, b ecause in most cases there are readily available substitutes for those services, even if accessing them involves incurring some
transition costs.

Finally, value can also be calculated using the co ntribution of the resource as an input into a productive process. This appr oach can be used for both m arket and non-market inputs

. For example, it can be used to estimate the value of fertilizer, as well as water or soil, in farm output and profits. An ecosystem’s service input into a pr oductive process could, in theory, be used in this same way.

Issues in Valuation and Aggregation
The topic of issues in valuation is far larger than can be covered here

. W e focus only on identifying in a superficial way a few of the mo st important issues, in the context of climate change.

By virtue of the simple process of aggregati on, the econom ic approach creates some difficulties. These difficulties are not sp ecific to the economic appr oach, however; any method of aggregation would face the same limitations.

4 -61SAP 4.6 Chapter 4: Human Welfare

 Aggregation, by balancing out effects to pr oduce a “net” effect, masks the positive and negative effects that comprise net effects, hides inequities in the distribution of impacts, or large negative impacts that fall on pa rticular regions or vulnerable populations.

 Any method of aggregation must make an e xplicit assum ption about how to aggregate over time, i.e., whether to weight future benefits the same as current benefits (economic analyses generally discount the future, i.e., weight it less heavily in decision making than the present, for a number of reasons)

 The method of putting diverse impacts on the sa m e yardstick ignores differences in how we may wish to treat these impacts from a policy perspective, and assumes that all impacts are equally certain or uncertain, desp ite differences in estimation and valuation methods. These differences may be particular ly apparent, for example, for non-market and market goods.

Several potential criticisms of the economic appro ach in the context of clim ate change relate more directly to how economists approach the task of valuation

. One issue is the assumption of stability of preferences over time

. Economic studies conducted today, whether revealed or stated preference, reflect the actions and preferences of individuals today, expressed in today’s economic, social, and technological context. For an issue such as climate change, however, impacts may occur decades or centuries hence. The valuation of impacts that occur in the future should depend on preferences in the future. For the most part, however, while there are some rudimentary ways in which economists model changes in technology or income, there is no satisfactory means of modeling ch anges in preferences over time

.

A second issue is the treatment of uncertainty. Econ omic analysis under conditions of imperfect information and uncertainty is possible, but is one of the most difficult undertakings in economics. While some climate change impacts may be relatively straight-forward, valuation of many climate change impacts requires analysis a nd use of welfare measures that incorporate uncertainty. When imperfect information prevails, the valuation measure must factor in errors that arise because of it, and when risk or uncer tainty prevail, the most commonly used valuation measure is the option price. Two related concep ts are option value, and expected consumer’s surplus. All three concepts are more complicated than the discussion here can do justice to, but briefly:

 Expected consumer’s surplus, E[CS] is just consumer’s surplus (CS) , or value in welfare terms, weighted by the probabilities of outcome s that yield CS. For example, if a hiker gets $5 of CS per year in a “dry” forest and $10 in a wet forest (one that is greener) and the probability of the forest being dry is 0.40 and of it being wet is 0.60, then the E[CS] = 0.40 X $5 + 0.60 X $10. Expected consumer’s surplus is really an ex-post concept,
because we must know CS in each state after it occurs.

 Option price (OP) is the WTP that balances expect ed utility (utility weighted by the probabilities of outcomes) with and without some change. It is a measure of WTP the individual must express before out comes can be known with certainty, i.e., a true ex ante welfare measure. For example, the hiker might be willing to pay $8 per year to balance her expected utility with conditions being we t, versus conditions being dry. The $8 might be a payment to support a reduction in dr yness otherwise due to climate change.

4 -62SAP 4.6 Chapter 4: Human Welfare

 Option value (OV) is the difference between OP and E[CS]. A related concept is called quasi-option value and pertains to the va lue of waiting to get more information.

A third issue concerns behavioral paradoxes. Mo st economic analyses, particularly if they involve uncertain or risky outco m es, require rationality in the expression of preferences

. Such basic axioms as treating gains a nd losses equally, reacting to a series of small incremental gains with equal strength to a single large gain of the same aggregate magnitude, and viewing gains
and losses from an absolute rather than relative or positional scale are particularly important to studies that rely on expected utility theory - th at individuals gain and lose welfare in proportion to the product of the likelihood of the gain or loss and its magnitude

. Several social and psychological science studies, however, suggest that under many conditions individuals do not
behave in a manner consistent w ith this definitio n of rationality

. For example, prospect theory, often credited as resulting from the work of Daniel Kahneman and Amos Tversky, suggests that behavior under risk or uncertainty is better explained both by refe rence to a status quo reference point and acknowledgement of unequal treatment of risk aversion when considering losses and gains, even when it can be shown that a differe nt behavior would certain ly make the individual
better off

.

Finally, the issue of perspectiv e—“whose lens are we looking th rough"—is critical to welfare analysis, particularly economi c we lfare. In health policy, for exam ple, thinking about whether it is worthwhile to invest in mosquito netting to control malaria depends on whether you are at CDC, are a provider of health insurance, or are an individual in a place where malaria risk is high. In general, the perspective of valuation focuses on the valuation of individuals who are directly affected, and who are living today. The perspectives of public decision makers may be somewhat different from those of individuals, since they will take into account social and community consequences, as well as individual consequences.

4 -63SAP 4.6 Chapter 4: Human Welfare



### 4.8 Boxes

Box 4.1 Effects of Climate Change on Selected US Ecosystems

At their most extreme, community ch ang e s could result in the loss of entire habitats valued by the general public. For example, sea level rise puts much of the freshwater wetland that comprises Florida Everglades National Park at risk (Glick and Clough, 2006). Even rela tively modest sea level rise projections could result in the conversion of much of this low-lying area to brackish or intertidal marine and mangrove habitats

. Another such extreme example is alpine tundra habitat in mountain ranges in the contiguous states. Since tundra lies at the highest elevations, there is little or no opportunity fo r the plants and animals that comprise this ecosystem to respond to increasing temperatures by moving upward. Thus, one of the probable effects of climate change will be the further fragmentation and loss of this unique habitat (VEMAP, 1995; Root et al.

, 2003; Lenihan et al. , 2006)

.

California already reports an example of how clim ate chan ge might modify major marine ecological
communities. Over the final four decades of the 20 th century the average annual ocean surface temperature off
the California coast warmed by approximately 1.5 o C (Holbrook et al. , 1997). Sagarin et al. (1999) found that the intertidal invertebrate community at Monterey has changed since first it was characterized in the 1930s. Many of the coolwater species have retracted their ranges northward, to be replaced by southern warm water species. The community that exists th ere now is markedly different in its make-up from that which existed prior to warming of the coastal California Current.

4 -64SAP 4.6 Chapter 4: Human Welfare

4 -65 Box 4.2 Case Study of the Effects of Climat e Change on Rocky Mountain National Park

One of the National Parks most closely studied to determine the net effect of direct and indirect effect of climate change on visitation, visitor benefits and tourism employment is Rocky Mountain National Park (RMNP) in Colorado. This al pine national park is located at elevations ranging from 7,000 to 14,000 feet above sea level. It is known for elk viewing, hiking, tundra flowers, snowcapped peaks, and one of Colora do’s most visible and recognizable 14,000 foot peaks, Longs Peak.

Loomis and Richardson (2006) compared two approaches to estimating the effect of climate change on visitation and employment in RMNP. The first approach examined variations in monthly visitation in response to historic variations in temperat ure. The results of this first approach showed a statistically significant posit ive effect of temperature on visitation (see Loomis and Richardson (2006) for more details) . However, increased visitation slowed as temperatures got hotter and hotter, and visitation even declined during one summer of very high temperatures (60 days over 80°F) by 7.5%.

The second approach used a survey th at portrayed the direct effects ( e.g., temperature) and indirect effects ( e.g., changes in elk and ptarmigan (an alpine bird), or percent of the park in tundra). Visitors were then asked to indicate if they would change their visits to RMNP or length of stay in the park. The surveys used three climate change scenarios, one produced by the Canadian Climate Center (CCC) indicating a 4°F increase in temperature by 2020, a Hadley climate scenario that forecasted a 2°F temp erature increase by 2020, and an extreme heat scenario designed to capture very hot future conditions (50 days with temperatures above 80°F, as compared to 3 days currently). All climate chan ge scenarios were used with wildlife models to estimate the increase in elk populations and decr ease in ptarmigan populations. The extreme heat survey found similar results to that of the monthly visitation model.

Table 4.6 shows the results of the CCC, Hadle y, and Extreme Heat temperature scenarios on visitation, visitor benefits and tourism employ ment as compared to current conditions. As indicated in the table, applying visitor survey estimates of vi sitation change yields a 13.6%
increase with CCC and 9.9% increase with Hadl ey. Loomis and Richardson also report that applying the historic visitation pa tterns to the same scenarios yields an 11.6% increase in visitation with CCC and 6.8% with Hadley. Not only is there fairly good agreement between the two methods, but the warmer CCC climate cha nge scenario produces larger increases in visitation. In the extreme heat scenario, however , visitations declines from current conditions.SAP 4.6 Chapter 4: Human Welfare4 -664.9 TablesTable 4.1 Categorizationof Well-BeingCategory of WellbeingDescription and RationaleComponents / Indicators ofWell-beingIllustrative Metrics / Measures of Well-beingExamples of Negative ClimateLinkages*EconomicconditionsThe economy supports a mix of activities:opportunities for employment, a strongconsumer market, funding for neededpublic services, and a high standard ofliving shared by citizens.Income and productionEconomic standardof living,e.g.,wealth andincome, cost of living, povertyEconomic development,e.g.,business andenterprise, employmentAvailability of affordable housingEquity in the distribution of incomeGross Domestic Product(GDP)Wage rates (e.g.,persons at minimum wage)EmploymentratesBusiness startupsand job creationHousing pricesDependence on public assistanceFamilies/children living in povertyUtility costs, gasoline prices, and other pricesReduced job opportunities and wage ratesin areas dependenton natural resources,such as agricultural production in a givenregion that faces increased drought.Higher electricity prices resulting fromincreased demand for Air Conditioning asaverage temperatures and frequency ofheat waves rise.Natural resources,environment, andamenitiesResources enhance the quality of life ofcitizens; pollution and other negativeenvironmental effects are kept belowlevels harmful to ecosystems, humanhealth, and other quality of lifeconsiderations;and natural beauty andaestheticsare enhanced.Air,water, and land pollutionRecreational opportunitiesWater supply and qualityNatural hazards and risksEcosystem condition and servicesBiodiversityDirectclimate amenity effectsAir and water quality indicesWaste recycling ratesAcreage,visitation, funding ofrecreational andprotected/preserved areasWater consumption and levelsDeaths, injuries, and property loss due tonatural hazardsEndangered and threatened speciesSea Level rise could both inundate coastalwetland habitats (with negative effects onmarsh and estuarine environmentsnecessary to purify water cycle systemsand support marine hatcheries) and eroderecreational beaches.Human healthHealth care institutions provide medicaland preventive health-care services withexcellence, citizens have access toservices regardless of financial means,and physical and mental health isgenerally high.Mortality risksMorbidity and risk ofillnessQuality and accessibility of health careHealth status of vulnerable populationsPrenatal and childhood healthPsychological and emotional healthDeaths from various causes (suicide, cancer,accidents, heart disease)Life expectancy at birthHealth insurance coverageHospital services and costsInfant mortality and care of elderlySubjective measure of health statusIncreased frequency of heat waves in alarger geographical area will directly affecthealth, resulting in higher incidence ofheat-related mortality and illness.Climatecan also affect human health indirectly viaeffects on ecosystems and water supplies.Public and privateinfrastructureTransportation and communicationinfrastructure enable citizens to movearound efficiently and communicatereliably.Affordable, and accessible public transitAdequate road, air, and rail infrastructureReliable communication systemsWaste management and sewerageMaintained and available public and privatefacilitiesPower generationMass transit use and commute timesRail lines,and airportuse and capacityTelephones,newspapers, and internetWaste tonnage and sewerage safetyCongestion and commute to workTransportation accident ratesNoise pollutionMelting permafrost due to warming in thearctic damages roadtransport, pipeline,and utility infrastructure,which in turn leadsto disrupted product and personalmovements, increased repair costs, andshorter time periods for capitalreplacement.Government andpublic safetyGovernments are led by competent andresponsive officials, who provide publicservices effectively and equitably, suchas order and public safety; citizens arewell-informed and participate in civicactivities.Electoral participationCivic engagementEquity and opportunityMunicipal budgets and financePublic safetyEmergency servicesVoter registration, turnout, approvalCivic organizations membership ratesAvailability of publicassistance programsDebt, deficits, taxation, and spendingCrime rates and victimizationEmergency first-responders per capitaDislocations and pressures created byclimate change stressors can placesignificant new burdens on police, fire andemergency services.Social and culturalresourcesSocial institutions provide services tothose in need, support philanthropy,volunteerism, patronage of arts andleisure activities, and social interactionscharacterized by equality of opportunityand social harmony.VolunteerismCulture, arts, entertainment, and leisureactivitiesEducation and human capital servicesSocial harmonyFamily and friendship networksDonations of time, money, and effortSports participation, library circulation, andsupport for the artsGraduation rates and school qualityHate, prejudice, and homelessnessDivorce rates, social supportsDisruptions in economic and political lifecaused byclimate change stressors orextreme weather events associated withclimate change could create new conflictsand place greater pressure on socialdifferences within communities.* The focus is on negative impacts as potentially more troublingfor quality of life; there are also positive impacts and opportunities in somecategoriesSAP 4.6 Chapter 4: Human Welfare

Table 4.2 An illustration of Possible Effects of Climate Change on Fishery Resources

Linkages/Pathways Category of Welfare Effect Possible Metrics

Fishery resource declines as climate changes Natural resources, environment, and
amenities F ish populations

Recreational opportunities decline Natural resources, environment, and

amen ities Fish catch, visitation day s
Related species and habitats are affected Natural resources, environment, and
amenities Speci es number and diversity

Employment and wages in resourcebased jobs (including recreation) fall
as resources decline Economic conditions Number of jobs, unemployment rate, w a ges
Incomes fall as jobs are lost Economic conditions Per capita income More children live in poverty as jobs are lost and incomes fall Economic conditions Families, children below poverty
level
Access to health care that is tied to jobs and income falls Human Health Households without health
insurance increase Increased mortality and morbidity as a result of reduced health care Human Health Disease and death rates increase

Working age population
decreases Lack of jobs results in out-migration Economic conditions

Fewer new residents attracted, because of reduced jobs and amenities (recreation) Social and cultural resources Population growth rate slows

Drop in volunteerism civic participation, completion of high
school Less incentive/drive to participate in
communit y activities Social and cultural resources

4 -67SAP 4.6 Chapter 4: Human Welfare

Table 4.3 Techniques to Value Health Effect s Associated with Climate Change

Health Effect Economic Valuation Tools

Premature mortality (associated with temperature changes, extreme weather events and air pollution effects) Use of revealed preference techniques to value changes in risk of death ( e.g., c omp ensating wage studies).
Use of stated preference studies to value changes in risk of death.
Use of foregone earnings as a lower bound estimate to the value of premature mortality.

Exacerbation of cardiovascular and respiratory morbidity; morbidity
associated with water-borne or
vector-borne disease Use of stated preference methods to elicit WTP to avoid illness ( e. g., asthma attacks) or risk of illness (heart attack risk) or injury. Estimation of medical costs and productivity losses (known as the cost-of-illness (COI)) as a lower
bou nd es timate of the value of avoiding illness.

Injuries associated with extreme
weather events Use of stated preference methods to elicit WTP.
Use of compensating wage studies that value risk of injury.

Use of COI as a lower bound estimate.

Impacts of climate change on physical functioning; sub-clinical
effects Use of stated preference methods to estimate WTP to avoid functional limitation.

4 -68SAP 4.6 Chapter 4: Human Welfare

Table 4.4 Examples of Ecosystem Services Important to Human Welfare*
Service Category Compon ents of Service Illustration of Service

Provisioning services Food
Fiber
Fresh water
Genetic Resources
Pharmaceuticals Harvestable fish, wildlife and plants Timber, hemp, cotton Water for drinking, hydroelectricity generation, and irrigation

Regulating services Air quality regulation Erosion regulation Water purification
Pest control Crop pollination Climate and water supply regulation
Protection from natural hazards Local and global amelioration of extremes Removal of contaminants by wetlands Removal of timber pests by birds Pollination of orchards by flying insects

Support services Primary production
Soil formation Photosynthesis Nutrient and water cycling Conversion of solar energy to plant material Conversion of geological materials to soil by
add itio n of organic material and bacterial activity

Cultural services Recreation/tourism
Aesthetic values Spiritual/religious values Cultural heritage Natural sites for “green” tourism/recreation/nature viewing
Ex

istence value of rainforests and charismatic

s

pec ies, “holy” or “spiritual” natural sites *Based on a classification system developed for the Millennium Ecosystem Assessment (MA, 2005)

4 -69SAP 4.6 Chapter 4: Human Welfare

Table 4.5 Comparison of Changes in US Visitor Days

Activity Loomis and Crespi (1999) Mendelsohn and Markowski (1999)
Boating 9.2% 36.1%
Camping -2.0% -12.7%
Fishing 3.5% 39.0%

Golf 13.6% 4.0%
Hunting -1.2% no ch ange Snow Skiing -52.0% -39.0%
Wildlife Viewing -0.1% -38.4%

Beach Recreation 14.1% not estimated

Stream Recreation 3.4% included in boating
Gain in Visitor Benefits (in Billions) $2.74 $2.80

4 -70SAP 4.6 Chapter 4: Human Welfare

Table 4.6 Change in Visits, Jobs and Visitor Benefi ts with Three Climate Change Scenarios

Annual Tourism Visitor
Climate Scenario Visits % change Jobs Benefits (Millions)
Current 3,186,323 6,370 $1,004

CCC 3,618,856 13.6% 7,351 $1,216 Hadley 3,502,426 9.9% 7,095 $1,157

Extreme Heat 2,907,520 -8.7% 5,770 $959

4 -71SAP 4.6 Chapter 4: Human Welfare



### 4.10 Figures

Figure 4.1 Geography of Climate Change Vulnerability at the County Scale

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Figure 4.2 Steps from Climate Change to Economic Valuation of Ecosystem Services

4 -73SAP 4.6 Chapter 4: Human Welfare

Figure 4.3 Direct and Indirect Effects of Climate Change on Recreation

Effects on Outdoor Recreation Climate Change : +Temperature +/- Precipitation +Climate Variability Use & Benefits : Enjoyment & Comfort while in
outdoors Visitor Days of outdoor recreation
demanded Benefits of outdoor recreation Direct

Effects of Climate Change : Changes in

. . .

. . . Vegetation (forests)

. . . Stream flows

. . . Reservoir levels

. . . Recreational Fisheries

. . . Wildlife populations

. . . Miles of Beaches

. . . Snow, Ice

. . . Length of season Indirect

4 -74

## Synthesis and Assessment Product 4.6

Chapter 5: Common Themes and Research
Recommendat i ons

Convening Lead Author: Janet L. Gamble, U.S. Environmental Protection Agency

Lead Authors: Kristi e L. E bi, ESS, LLC; Frances G. Sussman, Environmental Economics Consulting; Thomas J. Wilbanks, Oak Ridge National Laboratory

Contributing Authors : Colleen E. R eid, ASPH Fellow; John V. Thomas, U.S. Environmental Protection Agency; Christopher P. Weaver, U. S. Environmental Protection Agency

5-1SAP 4.6 Chapter 5: Research

Table of Contents

5.1 Synthesis and Assessment Product 4.6: Advances in the Science....................................................... 3

5.1.1 Complex Linkages and a Cascading Ch ain of Im pacts Across Global Changes.............................. 3

5.1.2 Changes in Climate Extrem es and Climate Averages ....................................................................... 4

5.1.3 Vulnerable Populations and Vul n erable Locations .......................................................................... 5

5.1.4. The Cost of and Capacity for Adaptation .................................................................................

....... 6

5. 1.5 An Integrative Framework.................................................................................................

............... 6

5. 2 Expanding the Knowledge Base ...............................................................................................

............. 7

5. 2.1 Human Health Research Gaps...............................................................................................

........... 9

5.2.2 Human Settlement s Res e arch Gaps .......................................................................................... ...... 10

5.2.3 Human Welfare Rese arch Gaps.............................................................................................. ........ 10

5-2SAP 4.6 Chapter 5: Research



### 5.1 Synthesis and Assessment Pr oduct 4.6: Advances in the
Science

The Synthesis and Assessment Product 4.6 assess es the impacts of c limate variability and change on human systems in the United States. Each of the assessment chapters have drawn on different literatures, with genera lly more available scientific knowledge on impacts and adaptations related to human health, somewhat less related to human settlements, and still somewhat less related to human welfare.

Several themes recur across these chapters and point to advances in the science of climate impacts assessm ent and the development and deployment of adaptation responses.

1. Climate change is connected to other environm ental and social changes in a complex and dynamic fashion. In some cases climate change compounds other global changes, while in othe r cases the impacts of climate change are determined or moderated by other socioeconomic factors (5.1.1).
2. Extreme weather events will play a defini ng role, particularly in the near term, shaping climate-related impacts and adaptive capacity. While impacts associated with changes in climate averages may be less important now, these averages are expected to have more pronounced long-r un effects on sea level rise, permafrost melt, glacial retreat, drought patterns and water supplies, etc. (5.1.2).
3. Climate change will have a disproportionate impact on disadvantaged groups in
communitie s across the United States. Some regions and some resources are more vulnerable to climate impacts, such as coastal zones, drought-prone regions, and flood-prone river basins (5.1.3).
4. Adaptation of infrastructure and services to climate change ma y be costly, but many communities will have adequate re sources. However, for places already struggling to provide or maintain ba sic public amenities and services, the additional costs of adaptation will im pose a potentially-insupportable burden (5.1.4.).
5. With such a complex scientific and policy landscape, an integrated multidisciplinary fra mework is needed to en able climate change impacts to be measured in meaningful ways and for op timal mitigation and adaptation strategies to be identified, developed, and deployed (5.1.5).

5.1.1 Complex Linkages and a Cascading Chain of Impacts Across Global Changes
Climate is only one of a number of global changes that impact hum an well-being. The major effects of climate will be shaped by in teractions with non-climate stressors. As such, climate change will seldom be the sole or primary factor determining a population’s or a location’s well-being. The impacts of c limate variability and change interact with impacts tied to population grow th and change and other socioeconomic endpoints (for example, impacts on infrastructure capac ity, water supplies, habitat preservation, community growth and development, and acces s to health care). While this assessment focuses on how climate change could affect th e future health, well-being, and settlements

5-3SAP 4.6 Chapter 5: Research

in the United States, the extent of any im pacts will depend on an array of non-climate factors, including:

 Demographic changes related to the loca tion, size, age and ch aracteristics of populations; population and regi onal vulnerabilities;

 Future social, economic, and cultural contexts;

 Availability of natural re sources;

 Human, cultural and social capital;

 Advances in science and technology;

 Characteristics of the built env ironment;

 Land use change;

 Public health and public utility infrastructures; and,

 The capacity and availability of health and social services.

The effects of climate change very often spr ead from directly impacted areas and sectors to other areas and sectors through extensiv e and complex linkages. The importance of climate change depends on the directness of the climate impact coupled with demographic, social, economic, institutional, and political factors, including, the degree of preparedness. Consider the damage le ft by Hurricanes Katrina and Rita in 2005. Damage was measured not only in terms of liv es lost, but also on the devastating impacts on infrastructure, neighborhoods, businesses, schools, and ho spitals as well as in the personal disruption of family and friends in established communities, with lost lives and lost livelihoods, challenged psychological well-being, and exacerbation of chronic illnesses. While the aftermath of a single hurri cane is not the measure of climate change, such an event demonstrates the disruptiv e capacity of extreme weather events.

5.1.2 Changes in Climate Ex tremes and Climate Averages.
Past and present clim ates have been, and are, variable. This variability in all likelihood
will continu e into the future. Changes in clim ate occur as changes in particular weather conditions, including extremes, in specific places (unfortunately, projections of climate changes at small geographic scales rema in highly uncertain). The meteorological
variables of interest from an impacts perspective include both changes in average conditions and in extreme conditions. More gr adual changes in average temperature and precipitation have the potentia l to strongly affect, both pos itively and negatively, human systems. For example, changes in the averag e length of the growi ng season can affect agricultural practices and changes in the timing and amount of spring runoff can affect water resource management. Effects such as these will not, however, be confined to a few individual sectors, nor are the eff ects across all sectors independent ( e.g., changes in water supplies can impact agricultural practices such as irrigation).

Changes in the climate extremes, both those that accompany changes in mean conditions ( e.g., a shif t in the entire temperature distribut ion) as well as change s in variability are very often of more concern than changes in climate averages. Unfortunately these types of changes ( e.g., heat waves, drought, storms, seasonal high or low levels of temperature or precipitation) have not always been pr ojected by climate change models. Many human systems have evolved to accommodate the “av erage climate” and some variation around

5-4SAP 4.6 Chapter 5: Research

this average. This evolution takes place in a dynamic social, economic, technological, biophysical and political context, which determ ine the ability of human systems to cope. Rapid onset extreme weather events in particul ar can do serious damage to a settlement’s infrastructure, public health, and overall commun ity reputation and qua lity of life, from which recovery may take years.

Finally key vulnerabilities ar e often defined by certain “thr esholds,” below which effects
are inciden tal but beyond where effects quickly become major. The seve rity of impacts is therefore not only related to th e rate and magnitude of clim ate change, but also to the presence or absence of thresholds. In genera l, these climate-relate d thresholds for human systems in the United States are not well- understood. Focused research on thresholds would substantially improve understanding of climate impacts.

5.1.3 Vulnerable Population s and Vuln erable Locations
Impacts of climate variability and cha nge on human syste ms are location- and population-specific. For instance, in dens ely-developed coastlines, populations are especially vulnerable to tropical storms, stor m surge and flooding, just as the very old and the very young residing in urban areas expe rience increases in cardiovascular and pulmonary morbidity and mortality caused by extreme heat coupled with degraded air quality. Native American peoples in Alaska and other low socio-economic communities because of their decreased economic capacity to prepare for and respond to the impacts of climate change. Just as there are differe nces across populations, there are important differences in vulnerability across geographic regions, such as the exposure to extreme events along the Gulf Coast and water supply issues in the southeas t, the southwest and
the Inter-Mountain West.

With respect to health impacts from c limate variability and change, specific subpopulations ma y experience heightened vulnera bility for climate-re lated health effects
associated with:

1. Biological s ensitivity related to age (especially th e very young and the very old), the presence of pre-existing chronic medical conditions (such as the sensitivity of people with chronic heart and pulmonary conditions to heat-related illness), developmental characteristics, acquired f actors (such as immunity), those taking certain medications ( e.g., some antihypertensive and psychotropic medications) and genetic factors (such as metabolic enzyme subtypes that play a role in vulnerability to air pollution effects).
2. Socioeconomic fa ctors also play a critical role in determining vulnerability to environmentally-mediated factors. The distribution of climate-related effects will vary among those who live al one; those with limited right s (for instance, some in the immigrant communities); by economic strata; by housing type and according
to other elements that either accentu ate or limit vulnerability. Socioeconomic factors may increase the lik elihood of exposure to harmfu l agents, interact with biological factors that mediat e risk (such as nutritional status), and/or lead to differences in the ability to adapt or re spond to exposures or to early phases of illness and injury.

5-5SAP 4.6 Chapter 5: Research

3. Given their location , the underlying vulnerability of some communities is inherently high just as thei r adaptive capacity is similarly limited. Populations in gently-sloping coastal areas are particul arly vulnerable to sea level rise and settlements along floodplains of large rivers ar e particularly vulnerable due to projections of increased va riability in preci pitation. Projections of increased frequencies of drought combined put the increasing populations of desert
southwest cities at risk.

It is essential that public h ealth interventions and preventi ons recognize populations that may experience interac tive or synergistic effects of multiple risk factors for health problems, both related to climate change a nd to other global changes. Poor communities and households are already under stress from climate variability and climate-related extreme events such as heat waves, hurrica nes, and tropical and riverine flooding. Since they tend to be concentrated in relatively high-risk areas, have limited access to services and other resources for coping, they can be especially vulnerable to climate change. These differential effects propagate concerns regarding social inequity and environmental justice and increased pressure for adaptive responses from local, state, and federal
governments.

5.1.4. The Cost of and Capacity for Adaptation
U.S. society is capable of considerable adaptation, depending heavily on the competence and capacity of individuals, comm unities, fe deral, state, and lo cal governments, and
available financial and other social resources . While adaptation to climate change will come at a cost that may reduce available reso urces to cope with other societal burdens, potentials for adaptation through technologi cal and institutional development and behavioral changes are consid erable, especially where such developments meet other sustainable development needs.

With scarce resources, communities should also choose adaptation option s with cobenefits that help ameliorate other issues or where they can easily add climate concerns to existing response plans. The focus on all-haza rds response within public health agencies can simply add climate impacts to its list of hazards for which to prepare. This will likely improve their response plans to events in the near term such as storms that happen in a variable climate, whether or not they increase in frequenc y or intensity with a changing climate. Planting trees and green roofs to re duce urban heat islands has the added benefit of creating a more aesthetic ally pleasing location that increasing well-being and by decreasing energy use in these buildings. T hus, some adaptation measures can also considered mitigation measures.

5.1.5 An Integrative Framework
The impacts of climate variability and cha nge on huma n health and human settlements are fairly well characterized in broad terms, although additional research is needed to refine impact assessments and provide better decision support (particularly with respect to deploying adaptation measures). Human we ll-being is an emerging concept, and in theory could encompass human health and se ttlements. As an organizing principle, human well-being could provide a paradigm for identifying and categorizing climate

5-6SAP 4.6 Chapter 5: Research

impacts, and may ultimately provide a framew ork for integrating multiple impacts into an internally-consistent, coherent framework fo r assessing costs, benefits, and tradeoffs. The potential for utilizing concepts of human we ll-being to develop an integrating framework is not yet mature. Additional conceptual work and research will be needed, such as valuation methodologies (in th e case of economic welfare), or developing metrics of well-being or quality of life (i n the case of a place-based indi cators, or similar, approach). As an integrating concept, human well-being can provide insight into the determinants of human happiness. Just as health can be considered a component of well-being ( i.e., physical health is closely tie d to individual measures of happiness, contentment, and quality of life) aspects of human settlemen ts also determine well-being and could be incorporated into a broader fram ework of well-being or welfare.

An alternative integrating framework coul d revolve around settleme nts or the more expansive concept of communities (See Secti on 4.2.3 for a fuller discussion). There is a growing awareness that the built environmen t can have a profound impact on our health and quality of life 1 . A major goal of community design is to create more vibrant and livable communities, making sure that they address the needs of residents and improve their quality of life. More specifically, “Green communities”, “Smart communities”, “Smart growth” and “Sustainable developmen t” are intended to offer alternatives to traditional settlement patterns, aiming to meet the goals of creating livable, desirable communities while minimizing the collective footprint of communities on natural resources, ecosystems and pollution. As an integrating framework, communities could be evaluated based on how well they protect hum an health and welfare. Put slightly differently, adaptation could be realized as increasing resilience within communities. Resilience is measured by a community’s cap acity for absorbing climate changes and the
shocks of extreme events without breakdow ns in its economy, natural resources, and social systems. Resiliency, as a central co ncept in measuring the vulnerability and adaptability of communities a nd individuals, depends not onl y on physical infrastructure,
but also on social infrastructu re and the natural environment. As with welfare, these concepts involving settlements or communitie s as an integrating framework are not yet

mature.



### 5.2 Expanding the Knowledge Base

The present state of the science suggests that opportunities remain fo r addressing critical
research areas. The SAP 4.6 concludes th at climate observations and modeling are becoming increasingly important for a wide segment of public and private sector entities, such as water resource managers, public health officials, agribusinesses, energy providers, forest managers, insurance compan ies, and urban and transportation planners. In order to more accurately portray the c onsequences of climate change and support better-informed adaptation strategies, research efforts should focus on:

 Deriving socioeconomic scenarios that desc ribe how the world m ay evolve in the future, including assumptions about ch anges in societal characteristics,

1 See for example, the CDC web-site on healthy places: www.c dc.gov/healthyplaces/

5-7SAP 4.6 Chapter 5: Research

governments and public policy, as we ll as economic and technological development;

 Connecting those socioeconomic scenario s with downscaled clim ate models to create projections of future changes in climate, including the intensity and severity of extreme weather events, at the regional and local scales;

 Characterizing the cost s of climate change , both those that relate to impacts and those that relate to response strategies (including adaptation and mitigation);

 Estimating the damages avoided by st abilizing or reduc ing emissions;

 Determining the factors that contribute to synerg ies between adaptive capacity and sustainable development as well as synergies between adaptation and mitigation;

 Pursuing cross-disciplinary efforts that focus on the human di mensions of climate change in an integrated fashion;

 Improving capacity to incorporate scientif ic knowledge about clim ate, including uncertainty, in existing adaptation strategies;

 Conducting research at regional and sectoral levels that promote analyses of the response of hum an and natural systems to multiple stresses. Impacts of climate change are most damaging when they occu r in a context of multiple climate and non-climate stressors;

 Evaluating the adaptation strategies that effectively address challenges presented by current non-clim ate stressors ( e.g., land use and population dynamics) as well as anticipated climate change impacts and develop comprehensive estimates of these co-benefits;

 Implementing adaptation measures to addr ess the near- and long-term responses to climate change, using regional and local stakeholders as key stakeholders in the development of effective, responsiv e, and timely adaptation policies;

 Advancing the concept of huma n welfare as an integrating framework by developing methods to achieve comparable and comprehensive valuations across diverse impacts and sectors;

 Determining which climate impacts exhibi t thresholds. Threshold-based dam age functions can be fundamentally different in their nature and extent than continuous damage functions;

 Supporting research on impacts and the development, i mplementation and evaluation of adaptive responses by collecting high quality time-series
measurements and other observations of both climate and human systems; and,

 Identifying early effects of changing weather patterns on climate-sensitive

outcom es.

This report concludes that periodic assessm ents of the impacts of global change on
hum an health, human settlements, and human welfare are necessary to support a rapidly developing knowledge base, especially related to impacts and adaptation. Gaps should be
addressed that characterize e xposure and sensitivity at th e local or regional level.Research should evaluate the adaptive capacity of places and institutions to climateinduced risks. Key research and developm ent areas should address short-term risk
assessment and evaluation of the costs and effe ctiveness of near-term adaptive strategies as well as longer-term impacts and responses.

5-8SAP 4.6 Chapter 5: Research

The following sections provide a more deta iled discussion of research needs and recommendations by topic: hum an health, human settlements, and human welfare. There is significant overlap across t opics with opportunities for investigating cross-disciplinary pursuits of research opportuni ties and adaptation responses.

5.2.1 Human Health Research Gaps
An important shift in perspective has occurred since the Health Sector Ass essment of the
First National Assessment in 2001. There is a greater appreciation of the complex pathways by which weather a nd climate affect individual an d societal health and wellbeing. In the research community, there is a more finely-honed understanding of the interaction of multiple non-climate, social, and behavioral factors and impacts on risks from injury and disease. While significant ga ps remain, several gaps identified in the
First National Assessment have been addressed, including:

 A more finely honed understanding of th e differential effects of tem perature extremes by community, demographic, and biological characteristics;

 Improved characterization of the exposure-response relationships to extrem e heat; and,

 Improved understanding of the public health burden posed by climate-related changes from heat waves and air pollution. Despite these advances, the body of l iterature has only limited quantitative projections of future impacts. Research rela ted to the human health im pacts of climate change will lead to a bett er understanding in this area.

The following specific suggestions for resear ch on climate change and hum an health:

 Increase the skill with which we characterize exposure-response relationships, including identifying thres holds and particularly vul nerable groups, considering relevant factors that affect the geographi c range and incid ence of climate-sensitive health outcomes, and including diseas e ecology and transmission dynamics;

 Develop quantitative mo dels of possible he alth impacts of climate change that can be used to explore a range of so cioeconomic and climate scenarios;

 Evaluate effectiveness o f current adap tation projects, including the costs and benefits of interventions. For example, heat wave and health early warning systems have not been effective; furthe r research is needed to understand how public health messages can be made more helpful;

 Character ize with local stakeholders the local and regional scale vulnerability and adaptive capacity related to the potential risks and the time horizon over which climate risks might arise; and,

 Anticipate requireme nts for infrastructure such as may be needed to provide protection against extreme events, to alte r urban design to decrease heat islands, and to maintain drinking and wastewater treatment standards and source water and watershed protection.

5-9SAP 4.6 Chapter 5: Research

5.2.2 Human Settlements Research Gaps
Chapter 3 examines the vulnerabilities and im pacts of climate change and variability on
hum an settlements. The following list enumerat es topics where a better understanding of the linkages between climate change a nd human settlements is appropriate.

 Advance the understanding of settlem ent vulnerabilities, impacts, and adaptive responses in a variety of different local contexts around the country.

 Develop plans for out-migration from vulnera ble locations vi a realistic, socially acceptable strategies for shifting human popul ations away from vulnerable zones.

 Improve the understanding of vulnerable populations (such as the urban poor and native populations on rural, tribal lands) that have limited capacities for response to climate change in order to provide a ba sis for adaptation research that addresses social justice and environm ental equity concerns.

 Improve the understanding of how urban decision-making is changing as populations becom e more heterogene ous and decisions become more decentralized especially as th is affects adaptive responses.

 Improve abilities to associate projections of climate change in U.S. settlements with changes in other driving forces re lated to impacts, such as changes in metropolitan/urban patterns, changes in transportation infrastructure and technological change. With continued growth in vulnerable regions, research is needed to consider alternative growth fu tures and to minimize the vulnerability of new development, to insure that communities adopt measures to manage significant changes in sea level, temperature, rainfall and extreme weather events.

 Improve the understanding of relationship s betw een settlement patterns (both regional and intra-urban) and resilience/adaptation.

 Improve the understanding of vulnerabil ities of urban population inflows and
outflows to clim ate change impacts.

 Improve the understanding of second and thir d-order im pacts of climate change in urban environments, including interactive effects among different aspects of the urban system.

 Review current policies and pr actices related to climate change responses to help
inform community decision-makers and ot her stakeholders about potentials for relatively small changes to make a large difference.

Meeting these needs is likely to require well-d eveloped partnerships across local, state, and federal governme nts, industry, non-gove rnmental organizations, foundations, stakeholders, resource managers, urban pl anners, public utilit y and public health authorities, and the academ ic research community.

5.2.3 Human Welfare Research Gaps
Despite the potential for imp acts on huma n well-being, little research focuses directly on understanding the relationship between well -being and climate change. Completely cataloging the effects of global change on hum an well-being or welfare would be an immense undertaking, and no well-accepted stru cture for doing so has been developed and applied. Moreover, identifying the potenti ally lengthy list of climate-related changes in lifestyle, as well as in other, more tangible, features of well-being (such as income), is

5-10SAP 4.6 Chapter 5: Research

itself a daunting task—and may include change s that are not easily captured by objective measures of well-being or quality of life.

Developing an understanding of the impacts of climate change on hum an welfare will require steps designed to deve lop a framework for addressi ng individual and community welfare and well-being, as well as to fill the data gaps associ ated with the estimation and quantification of effects.

Regarding climate change and human welfare, th ere is a range of topics associated with
hum an welfare impacts and adaptations wher e improved understanding would be useful.

 Design an appropriate me thod for system atically categorizing and identifying impacts on welfare/well-being.

 Identify priority categories for data colle ction and research in order to establish and quantify the linkage from climat e to effects on welfare/well-being.

 Decide which me trics should be used for these categorie s; more generally, which components of welfare/well-being should be measured in natural or physical units, and which should be monetized.

 Investigate me thods by which diverse metr ics can be aggregated, or at least weighted and compared in policy decisi ons where aggregation is impossible.

 Develop an approach for addressing those human welfare effects th at are difficult to look at in a piecemeal way, such as welfare changes on communities or ecosystem services.

 Identify appropriate top-down and botto m -up approaches for estimating impacts and value (whether economic or otherwise) of the most critical categories of welfare/well-being.

Together, these steps should enable research ers to ma ke progress towards promoting the consistency and coordination in analyses of welfare/well-being that will facilitate developing the body of research necessary to analyze impacts on human welfare, wellbeing, and quality of life.

5-11SAP 4.6 Glossary and Acronyms



## 6 Glossary and Acronyms

6.1 Glossary

Sources: Derived from the Intergov ernmental Panel on Climate Change Third and Fourth Assessment Reports, Working Group II and other sources as
indicated.

Words in italics indicate that the following term is also contained in this glossary.



## A

Acclimatization The physiological adaptation to climatic
variations. Adaptability
See Adaptive capacity

. Adaptation Adjustment in natural or human systems to a new or changing envir onment. Adaptation to climate change refers to adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities. Various types of adaptation can be distinguished, including anticipatory and reactive adaptation, private and public adaptation, and autonomous and planned adaptation. Adaptation assessment The practice of identifying options to adapt

to climate change and eval uating them in terms of criteria such as availability, benefits, costs, effectiveness, efficiency, and feasibility. Adaptation benefits The avoided damage costs or the accrued
benefits follo wing the ado ption and implementation of adaptation measures. Adaptation costs Costs of planning, preparing for, facilitating, and implementing ada ptation measures, including transition costs. Adaptive capacity The ability of a system to adjust to climate change (inclu ding climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with the consequences. Aeroallergens 1 Any of various airborne substances, such as pollen or spores, that can cause an allergic

response. Aggregate impacts Total impacts summed up across sectors and/or region s. The aggregation of impacts requires knowledge of (or assu mptions about) the relative importance of impacts in different sectors and regions. Measures of aggregate impacts include, for example, the total number of people affected, change in net primary productivity, number of systems undergoing change, or total economic costs.
Albedo The fraction of solar radiation reflected by a surface or object, often expressed as a percentage. Snow-covered surfaces have a high albedo; the albedo of soils ranges from high to low; vegetation-covered surfaces and
oceans have a low albedo. The Earth’s albedo varies mainly through varyingcloudiness, snow, ice, leaf area, and landcover changes.

1 The American Heritage® Dictionary of the English Language, Fourth Edition . Retrieved November 21, 2007, from Dictionary.com
website: http://dictionary.reference.com/browse/aeroaller

gen

6-1SAP 4.6 Glossary and Acronyms

Algal bloom A reproductive explosion of algae in a lake,
river or ocean. Ancillary benefits The ancillary, or side effects, of policies
ai m ed exclusively at climate change mitigation . Such policies have an impact not only on greenhouse gas emissions , but also on resource use efficiency, like reduction in emissions of local and regional air pollutants
associated with fossil-fuel use, and on issues such as transportation, agriculture, land-use practices, employment, and fuel security.
Sometimes these benefits are referred to as “ancillary impacts” to reflect that in some cases the benefits may be negative. From the perspective of policies directed at abating local air pollution, greenhouse gas mitigation may also be considered an ancillary benefit, but these relationships are
not considered in this assessment. Anthropogenic Resulting from or produced by human beings. Anthropogenic emissions

Emissions of greenhouse gases , greenhouse

gas precursor s , and aerosols associated with human activities. These include burning of fossil fuels for energy, deforestation , and
land-use changes that result in net increase
in emissions. Aquifer A stratum of permeable rock that bears water. An unconfined aqui fer is recharg ed directly by local rainfall, rivers and lakes, and the rate of recharge will be influenced by the permeability of the overlying rocks
and soils. Arid regions Ecosystems w ith less than 250 mm precipitation per year. Atmosphere The gaseous envelop surrounding the Earth. The dry atm osphere consists almost entirely of nitrogen (78.1% volume mixing ratio ) and oxygen (20.9% volume mixing ratio), together with a number of trace gases, such as argon (0.93% volume mixing ratio), helium, and radiatively active greenhouse

gases such as carbon dioxide (0.035% volume mixing ratio) and ozone . In addition, the atmosphere contains water vapor, whose amount is highly variable but typically 1% volume mixing ratio. The atmosphere also
contains clouds and aerosols

.



## B

Baseline The baseline (or reference) is any datum against which change is measured. It m ight be a “current baseline,” in which case it represents observable, present-day conditions. It might also be a “future baseline,” which is a projected future set of conditions excluding the driving factor of interest. Alternative interpretations of the reference conditions can give rise to multiple baselines.
Biofuel A fuel produced from organic matter or
bom bustible oils prod uced by plants. Examples of biofuel include alcohol, black liquor from the paper-manufacturing process, wood, and soybean oil. Biogenic 2 Produced by living organisms or biological

processes.



## C

Carbon dioxide (CO2)A naturally occurring gas, and also a byproduct of bu rning fossil fuels and biomass

, as well as land-use changes and other industrial processes. It is the principal anthropogenic greenhouse gas that affects
the Earth’s radiative balance . It is the reference gas against which other greenhouse gases are measured and has a Global Warming Potential of 1.
Cholera
An intestinal infection that results in frequent watery st ools, cramping abdominal

2 The American Heritage® Dictionary of the English Language, Fourth Edition . Retrieved November 21, 2007, from Dictionary.com
website: http://dictionary.reference.com/browse/biogenic

6-2SAP 4.6 Glossary and Acronyms

pain, and eventual collapse from dehydration. Chronic obstructed pulmonary disease (COPD) 3 Chronic obstructive pulmonary disease, or COPD, refers to a group of diseases that cause airflow blockage and breathing-related problems. It includes emphysema, chronic bronchitis, and in some cases asthma.
Climate Climate in a narrow sense is usually defined
as the “aver a ge weather” or more rigorously as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These relevant quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system

. Climate change Climate change refers to any change in
climate over time , whether due to natural variability or as a result of human activity. This usage differs from that in the United
Nations Framework Convention on Climate Change (UNFCCC) , which defines ‘climate change’ as: ‘a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’. See also climate variability

. Climate change commitment
Due to the thermal inertia of the ocean and slow processe s in the biosphere, the cryosphere and land surfaces, the climate would continue to change even if the atmospherica composition was held fixed at today’s values. Past changes in atmospheric position leads to a ‘committed’ climatic change which continues for as long as a radiative imbalance persists and until all

3 Definition taken from http://www.cdc.gov/nceh/airpollution/copd/copd faq.htm visited on November 21, 2007. components of the climate system have adjusted to a new state. The further change in temperature after the composition of the atmosphere is head constant is referred to as the committed warming or warming commitment. Climate change commitment includes other future changes, for example in the hydrological cycle, in extreme weather events , and in sea-level rise. Climate model (hierarchy) A numerical representation of the climate
syste m based on the physical, chemical, and biological properties of its components, their
interactions and feedback processes, and accounting for all or some of its known properties. The climate system can be represented by models of varying complexity—that is, for any one component or combination of components a “hierarchy” of models can be identified, differing in such aspects as the number of spatial dimensions, the extent to which physical, chemical or biological processes are explicitly represented, or the level at which empirical parametrizations are involved. Coupled atmosphere/ocean/sea-ice general
circulation models (AOGCMs) provide a comprehensive representation of the climate system. There is an evolution towards more complex models with active chemistry and biology. Climate models are applied, as a research tool, to study and simulate the climate, but also for operational purposes, including monthly, seasonal, and interannual climate predictions

. Climate prediction A climate prediction or climate forecast is
the result of an atte m pt to produce a most likely description or estimate of the actual
evolution of the climate in the future (e.g., at seasonal, interannual, or long-term timescales ). See also climate projection and climate (change) scenario

. Climate projection
A projection of the response of the climate
syste m to emission or concentration

scenarios of greenhouse gases and aerosols

,
or radiative forcing scenarios , often based upon simulations by climate models

. Climate projections are distinguished from climate predictions in order to emphasize

6-3SAP 4.6 Glossary and Acronyms

that climate projections depend upon the emission/concentration/radiative forcing scenario used, which are based on assumptions, concerning, for example, future socio-economic and technological developments that may or may not be realized, and are therefore subject to
substantial uncertainty

. Climate scenario A plausible and often simplified representatio n of the future climate , based
on an internal ly consistent set of climatological relationships, that has been constructed for explicit use in investigating the potential consequences of anthropogenic climate change , often serving as input to impact models. Climate projections often serve as the raw material for constructing climate scenarios, but climate scenarios usually require additional information such
as about the observed current climate. A “climate change scenario” is the difference
between a climate scenario and the current
climate. Climate system The climate system is the highly complex

sy stem consisting of five major components:
the atmosphere , the hydrosphere , the cryosphere , the land surface and the biosphere , and the interactions between them. The climate system evolves in time
under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations, and human-induced forcings such as the changing composition of the atmosphere and land-use change

. Climate variability Climate variability refers to variations in the

mean state an d other statistics (such as standard deviations, the occurrence of extremes, etc.) of the climate on all temporal and spatial scales beyond that of individual weather events. Variability may be due to natural internal processes within the climate
system (internal variability), or to variations
in natural or anthropogenic external forcing (external variability). See also climate change

. Co-benefits The benefits of policies that are
im plem ented for various reasons at the same time—including climate change mitigation — acknowledging that most policies designed to address greenhouse gas mitigation also have other, often at least equally important, rationales (e.g., related to objectives of development, sustainability, and equity). The term co-impact is also used in a more generic sense to cover both the positive and negative sides of the benefits.
See also ancillary benefits

. Communicable Disease
An infectious disease caus ed by transmission of an infective biological agent (virus, bacterium, protozoan, or multicellular macroparasite).
Confidence In this Report, the level of confidence in a

state m ent is expressed using a standard terminology defined in the Introduction. See
also uncertainty

. Coping range
The variation in climatic st imuli that a

sy stem can absorb without producing significant impacts.
Cost-effective A criterion that specifies that a technology
or measure d e livers a good or service at equal or lower cost than current practice, or
the least-cost alternative for the achievement of a given tar g et.



## D

DALY (Disability-adjusted life years) 4 The sum of years of life lost due to premature death and illness, taking into account the age of death compared with natural life expectancy and the number of years of life lived with a disability. The measure of number of years lived with the disability considers the duration of the disease, weighted by a measure of the severity of the disease. Dengue Fever

4 Definition from the glossary of the Millenium Ecosystem Assessment, 2005.

6-4SAP 4.6 Glossary and Acronyms

An infectious viral disease spread by mosquitoes often called breakbone fever because it is characterized by severe pain in joints and back. Subsequent infections of the
virus m a y lead to dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which may be fatal.
Desert
An ecosystem with less than 100 mm precipitation per year.
Desertification Land degradation in arid, se m i-arid , and dry sub-humid areas resulting from various factors, including climatic variations and human activities. Further, the United
Nations Convention to Combat Desertification defines land degradation as a reduction or loss in arid, semi-arid, and dry sub-humid areas of the biological or economic productivity and complexity of rain-fed cropland, irrigated cropland, or
range, pasture, forest , and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as: (i) soil erosion caused by wind and/or water; (ii) deterioration of the physical, chemical, and biological or economic properties of soil; and (iii) long-term loss of natural vegetation.
Detection and attribution
Climate varies continually on all time scales

. Detection of climate change is the process of demonstrating that climate has changed in some defined statistical sense, without providing a reason for that change. Attribution of causes of climate change is the process of establishing the most likely causes for the detected change with some
defined level of confidence. Disturbance regime Frequency, intensity, and types of disturbances, such as fires, inspect or pest outbreaks, flo ods, and droughts

. Diurnal temperature range
The difference between the maximum and
minimu m temperature during a day

. Dose-response function 5 A mathematical relationship is established
which relates how m uch a certain amount of exposure impacts on production, capital, ecosystems, human health etc. DownscalingA method that derives local- to regionalscale (10 to 100 km ) information from larger-scale models or data analyses. Drought The phenomenon that exists when precipitation has been significantly below normal recorded levels, causing serious hydrological imbalances that adversely affect land resource production s ystems.



## E

Ecosystem A system of interacting living organisms together with their ph ysical environment.
The boundaries of what could be called an ecosystem are somewhat arbitrary, depending on the focus of interest or study. Thus, the extent of an ecosystem may range from very small spatial scales to, ultim ately,
the entire Earth.

Ecosystem processes The processes that underpin the integrity and functioning of ecosy ste ms, such as decomposition, carbon cycling, or soil renewal, etc. Ecosystem services Ecological processes or functions that have

m onetary or non-monetary value to individuals or society. There are (i) supporting services such as productivity or biodiversity maintenance, (ii) provisioning services such as food, fibre, or fish, (iii) regulating services such as climate regulation or carbon sequestration , and (iv) cultural services such as tourism or spiritual and aesthetic appreciation. El Niño Southern Oscillation (ENSO)

5 Definition modified from http://stats.oecd.org/glossary/detail.asp?ID=6404 visited on November 21, 2007.

6-5SAP 4.6 Glossary and Acronyms

El Niño, in its original sense, is a warm water current that periodically flows along the coast of Ecuador and Peru, disrupting the local fishery. This oceanic event is
associated with a fluctuation of the intertropical surface pressure pattern and circulation in the Indian and Pacific Oceans,
called the Southern Oscillation. This coupled atmosphere-ocean phenomenon is collectively known as El Niño Southern Oscillation, or ENSO. During an El Niño event, the prevailing trade winds weaken and the equatorial countercurrent strengthens, causing warm surface waters in
the Indonesian area to flow eastward to
overlie the cold waters of the Peru current. This event has great impact on the wind, sea surface temperature, and precipitation patterns in the tropical Pacific. It has climatic effects throughout the Pacific region and in many other parts of the world. The opposite of an El Niño event is called

La Niña

. Emissions
In the climate change contex t, emissions
refer to the release of greenhouse gases
and/or their precursors and aerosols into the atmosphere over a specified area and period
of time.
Endemic Restricted or peculiar to a locality or region. With regard t o human health, endemic can refer to a disease or agent present or usually prevalent in a population or geographical
area at all times. Epidemi c Occurring suddenly in numbers clearly in excess of normal expectan cy , said especially
of infectious diseases but applied also to any disease, injury, or other health-related event occurring in such outbreaks. Eutrophication The process by which a body of water (often shallow) becomes ( e ither naturally or by pollution) rich in dissolved nutrients with a seasonal deficiency in dissolved oxygen. Evaporation The process by which a liquid becomes a

gas. Evapotranspiration The combined process of evaporation fr om the Earth’s surface and transpiration from vegetation. Exotic species
See introduced species

. Exposure The nature and degree to which a system is exposed to significant climatic variations. Externality
See ext ernal cost

. External cost
Used to define the costs ari sing from any human activity, when the a gent responsible for the activity does not take full account of the impacts on others of his or her actions. Equally, when the i mpacts are positive and not accounted for in the actions of the agent responsible they are referred to
as external benefits. Emissions of particulate pollution from a power station affect the health of people in the vicinity, but this is not often considered, or is given inadequate weight, in private decision making and there is no market for such impacts. Such a phenomenon is referred to as an “externality,” and the costs it imposes are
referred to as the external costs.
Extinction The complete disappearance of an entire species. Extirpation The disappearance of a species from part of its range; local extinction.
Extreme weather event
An extreme weather event is an event that is
rare within its statistical reference distribution at a particular place. Definit ions of “rare” vary , but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile. By definition, the char acteristics of what is
called extre m e weather may vary from place to place. An extreme climate event is an average of a number of weather events over a certain period of time, an average which is itself extreme (e.g., rainfall over a season).



## F

Food security

6-6SAP 4.6 Glossary and Acronyms

A situation that exists when people have
secure access to sufficient amounts of safe and nutritious food for normal growth, development and an active and healthy life. Food insecurity may be caused by the unavailability of food, insufficient purchasing power, inappropriate distribution, or inadequate use of food at the
household level.
Foodborne illness 6 An illness caused by consuming foods or beverages contaminated with any of many different disease-causing microbes, or pathogens, or poisonous chemicals, or other
harmful substances. Footprint (ecological) 7 An index of the area of productive land and aquatic ecosystems required to produce the
resources used and to assimilate the wastes produced by a defined population at a specified material standard of living, wherever on Earth that land may be located.
Forecast
See climate p rediction and climate projection

.



## G

General circulation The large scale motions of the atmosphe re and the ocean as a consequence of differential heating on a ro tating Earth, aiming to restore the energy balance of the system through transport of heat and

momentum. General Circulation Model (GCM)
See climate model

. GIS (Geographic Information Systems) 8 A computerized system organizing data sets through a geographical referencing of all
data included in its collections.

6 Definition modified from the Centers for
Disease Control and Prevention website: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/fo odborneinfections_g.htm, viewed on November 21, 2007.

7 From the glossary of the Millenium Ecosystem Assessment, 2005.

8 From the glossary of the Millenium Ecosystem Assessment, 2005. Global surface temperatureThe global surface temperature is the areaweighted global average of (i) the sea
surface te mpe rature over the oceans (i.e., the sub-surface bulk temperature in the first few meters of the ocean), and (ii) the surface air temperature over land at 1.5 m above the ground.
Globalization The growing integration and interdependence of countri es worldwide through the increasing volume and variety of crossborder transactions in goods and services, free international capital flows, and the more rapid and widespread diffusion of technology, information and culture.
Greenhouse effect Greenhouse gases effe ctive ly absorb infrared radiation , emitted by the Earth’s surface, by the atmosphere itself due to the same gases, and by clouds. Atmospheric radiation is emitted to all sides, including
downward to the Earth’s surface. Thus greenhouse gases trap heat within the surface-troposphere system. This is called the “natural greenhouse effect.” Atmospheric radiation is strongly coupled to the temperature of the level at which it is
emitted. In the troposphere, the temperature generally decreases with height. Effectively, infrared radiation emitted to space originates from an altitude with a temperature of, on average, -19°C, in balance with the net incoming solar radiation , whereas the Earth’s surface is kept at a much higher temperature of, on average, +14°C. An increase in the concentration of greenhouse gases leads to an increased infrared opacity of the atmosphere, and therefore to an effective radiation into space from a higher altitude at a lower temperature. This causes

a radiative forcing , an imbalance that can only be compensated for by an increase of the temperature of the surface-troposphere system. This is the “enhanced greenhouse
effect.” Greenhouse gas Greenhouse gases are those gaseous
constituents of the atmosphere , both natu ral
and anthropogenic , that absorb and emit radiation at specific wavelengths within the

6-7SAP 4.6 Glossary and Acronyms

spectrum of infrared radiation emitted by the Earth’s surface, the atmosphere, and clouds. This property causes the greenhouse effect . Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ozone (O3) are the primary greenhouse gases in the Earth’s atmosphere. Moreover there are a number of entirely human-made greenhouse gases in the atmosphere, such as the halocarbons and other chlorine- and bromine-containing substances, dealt with under the Montreal
Protocol . Besides CO2, N2O, and CH4, the Kyoto Protocol deals with the greenhouse

gases sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs).
Gross Domestic Product Gross Domestic Product (GDP) is the

m onetary value of all goods and services produced within a nation.
Gross National Product Gross National Product (GNP) is the

m onetary value of all goods and services produced in a nation’s economy, including income generated abroad by domestic residents, but without income generated by foreigners. Groundwater Recharge The process by which external water is
added to the z one of saturation of an aquifer

, either directly into a formation or indirectly by way of another formation.



## H

Habitat The particular environment or place where an organism or species tend to live; a more locally circumscribed portion of the total
environment.
Hantavirus A virus in the family Buny aviridae that

causes a type of haemorrhagic fever. It is thought that humans catch the disease mainly from infected rodents, either through direct contact with the animals or by inhaling or ingesting dust that contains aerosolized viral particles from their dried
urine and other secretions. Healthy Cities Program 9 The WHO Healthy Cities programme engages local governments in health development through a process of political commitment, institutional change, capacity building, partnership-based planning and innovative projects. It promotes comprehensive and systematic policy and planning with a special emphasis on health inequalities and urban poverty, the needs of vulnerable groups, participatory governance and the social, economic and environmental
determinants of health. It also strives to include health considerations in economic, regeneration and urban development efforts.
Heat exhaustion 10 Heat exhaustion is a phenomenon caused by fluid loss, which in turn causes decreased blood flow to vital organs. Reduced blood
flow from heat exhaustion can result in a
form of shock. Victims of heat exhaustion often complain of flu-like symptoms hours after exposure.
Heat index 11 The heat index (HI), given in degrees F, is a
measure of how hot it feels when relative humidity (RH) is combined with the actual air temperature.
Heat island
An area within an urban area characterized by am bient temperatures higher than those of the surrounding area because of the absorption of solar energy by materials like asphalt.
Heat stroke 12

9 Definition taken directly from http://www.euro.who.int/healthy-cities on November 21, 2007.

10 Definition from the U.S. Environmental Protection Agency’s Heat Island Glossary, http://www.epa.gov/hiri/r esources/glossary.html #h, visited on November 21, 2007.

11 Defintion modified from NOAA’s Heat Index website, http://www.crh.noaa.gov/jkl/?n=heat_index_calc ulator, visited on November 21, 2007.

12 Definition from the U.S. Environmental Protection Agency’s Heat Island Glossary, http://www.epa.gov/hiri/r esources/glossary.html #h, visited on November 21, 2007.

6-8SAP 4.6 Glossary and Acronyms

Heat stroke occurs when the body's heat regulating mechanisms – including convection, sweating, and respiration – fail.
The likelihood of heat stroke increases when air temperatures are higher than skin temperature, and when individuals are low on fluids. Body temperatures can be raised to the point at which brain damage and death can result unless cooling measures are quickly taken.
Human settlement A place or area occupied by settlers. Human system Any system in which human organizations play a major role. Often, but not alway s , the term is synonymous with “society” or “social system” (e.g., agricultural system, political sy ste m, technological system, economic system). Hydrological systems The systems involved in movement,
distributio n, a nd quality of water throughout the Earth, including both the hydrologic cycle and water resources. Hyperthermia 13 Unusually high body temperature.



## I

Ice sheet A mass of land ice that is sufficiently deep

to cover m o st of the underlying bedrock topography, so that its shape is mainly determined by its internal dynamics (the flow of the ice as it deforms internally and slides at its base). An ice sheet flows outward from a high central plateau with a small average surface slope. The margins slope steeply, and the ice is discharged through fast-flowing ice streams or outlet glaciers , in some cases into the sea or into
ice shelves floating on the sea. There are only two large ice sheets in the modern world, on Greenland and Antarctica, the

13 The American Heritage® Dictionary of the English Language, Fourth Edition . Retrieved November 21, 2007, from Dictionary.com
website: http://dictionary.reference.com/browse/hyperther
mia Antarctic ice sheet being divided into East and West by the Transantarctic Mountains; during glacial periods there were others.
Ice shelf A floating ice sheet of considerable
thickness atta ched to a coast (usually of great horizontal extent with a level or gently undulating surface); often a seaward
extension of ice sheets. (Climate) Impact assessment The practice of identifying and evaluating the detrimental and beneficial conseque nces of climate change on natural and human
systems

. (Climate) Impacts Consequences of climate change on n atural
and human systems . Depending on the
consideration of adaptation , one can distinguish between potential impacts and residual impacts. Potential impacts: All impacts that may occur given a projected change in climate , without considering adaptation. Residual impacts: The impacts of climate change that would occur after adaptation. See also a ggregate impacts

, market impacts , and non-market impacts

. Indicator 14

Information based on measured data used to represent a particular attribute, characteristic, or property of a system. Indigenous peoples People whose ancestors inhabited a place or

a countr y when persons from another culture or ethnic background arrived on the scene and dominated them through conquest, settlement, or other means and who today live more in conformity with their own social, economic, and cultural customs and traditions than those of the country of which they now form a part (also referred to as “native,” “aboriginal,” or “tribal” peoples).
Industrial RevolutionA period of rapid industrial growth with farreaching social and economic conseque nces, beginnin g in England during the second half of the 18th century and spreading to Europe and later to other countries including the

14 Definition taken from the Millenium Ecosystem Assessment, Current State and Trends Assessment Glossary, 2005

6-9SAP 4.6 Glossary and Acronyms

United States. The invention of the steam engine was an important trigger of this development. The Industrial Revolution marks the beginning of a strong increase in
the use of fossil fuels and emission of, in particular, fossil carbon dioxide . In this report, the terms “pre-industrial” and “industrial” refer, somewhat arbitrarily, to the periods before and after the year 1750, respectively.
Inertia Delay, slowness, or resistance in the response of the climate , biological, or human systems to factors that alter their rate of change, including continuation of change in the system after the cause of that change
has been removed.
Infectious diseases Any disease that can be transmitted from
one person to another. Thi s may occur by direct physical contact, by common handling of an object that has picked up infective organisms, through a disease carrier, or by spread of infected droplets coughed or
exhaled into the air.
Infrastructure The basic equipment, utilities, productive enterprises, in stallations, institutions, and services essential for the development, operation, and growth of an organization, city, or nation. For example, roads; schools; electric, gas, and water utilities; transportation; communication; and legal systems would be all considered as
infrastructure. Integrated assessment A method of analysis that combines results
and m odels from the physical, biological, economic, and social sciences, and the interactions between these components, in a consistent framework, to evaluate the status and the consequences of environmental change and the policy responses to it. Introduced species A species occurring in an area outside its historically known natural range as a result of accidental dispersal by humans (also
referred to as “ exotic species ” or “alien species”). Invasive species An introduce d species that invades natural
habitats

. IPCC 15 A panel set up by the United Nations in
1988 to review scientific information on climate change. This panel involves over 2,000 of the world’s climate experts. Many of the climate change facts and future predictions we read about come from information reviewed by the IPCC.



## K

Kyoto Protocol The Kyoto Protocol was adopted at the
Third Session of the Conference of the Parties (COP) to the UN Framework Convention on Climate Change (UNFCCC)
in 19 97 in Kyoto, Japan. It contains legally binding commitments, in addition to those
included in the UNFCCC. Countries included in Annex B of the Protocol (most member countries of the Organisation for Economic Cooperation and Development (OECD) and those with economies in transition) agreed to reduce their anthropogenic greenhouse gas emissions (CO2, CH4, N2O, HFCs, PFCs, and SF6) by
at least 5% below 1990 levels in the commitment period 2008 to 2012. The Kyoto Protocol entered into force on 16 February 2005.



## L

La Niña
See El Niño Southern Oscillation

. Land use The total of arrangements, activities, and inputs u ndert aken in a certain land cover type (a set of human actions). The social and economic purposes for which land is managed (e.g., grazing, timber extraction, and conservation). Land-use change

15 Definition taken from the Climate Change North Glossary at http://www.climatechange north.ca/H1_Glossary. html on November 21, 2007.

6-10SAP 4.6 Glossary and Acronyms

A change in the use or management of land by humans, which may lead to a change in land cover. Land cover and land-use change may have an impact on the albedo

, evapotranspiration

, sources , and sinks of greenhouse gases , or other properties of the climate system , and may thus have an impact

on climate , locally or globally.
Landslide A mass of material that has slipped downhill by gravity, often assisted b y water when the material is saturated; rapid movement of a mass of soil, rock, or debris down a slope.
Likelihood The likelihood of an occurrence, an outcome or a result, where this can be esti m ated probabilistically, is expressed in this Report using a standard terminology, defined in the
Introduction. See also uncertainty and confidence

. Lyme disease A vector-borne disease caused by the spirochete Borrelia burgdor feri and

transm itted by Ixodes ticks, commonly known as deer ticks. Symptoms include skin lesions, fatigue, fever, and chills, and if left untreated may later manifest itself in cardiac and neurological disorders, joint pain, and arthritis.



## M

Maladaptation Any changes in natural or human systems that inadvertently increase vulnerability to climatic stimuli ; an adaptation that does not succeed in reducing vulnerability but
increases it instead.
Malaria
Endemic or epidemic parasitic disease caused by species of the genus Plasmodium (protozoa) and transmitted by mosquitoes of the genus Anopheles; produces high fever attacks and system ic disorders, and kills approximately 2 million people every year.
Market barriers
In the context of mitigati o n of climate change , conditions that prevent or impede
the diffusion of cost-effective technologies or practices that would mitigate greenhouse gas emissions

. Market-based incentives Measures intended to use price mechanisms (e.g., taxes and tradable permits) to reduce greenhouse gas emissions

. Market impacts Impacts that are linked to market
transactions a nd directly affect Gross
Domestic Product (a country’s national accounts)—for example, changes in the supply and price of agricultural goods. See
also non-market impacts

. Mitigation
An anthro pogenic intervention to reduce the

sources or en hance the sinks of greenhouse

gases

. Mitigative capacity The social, political, and economic structures and conditions that are required
for effective mitigation

. Morbidity
Rate of occurrence of disease or other health
disorder withi n a population, taking account of the age-specific morbidity rates. Health
outcomes include chronic disease incidence/prevalence, rates of hospitalization, primary care consultations, disability-days (i.e., days when absent from work), and prevalence of symptoms. Mortality
Rate of occurrence of death within a population wi thin a specified time period; calculation of mortality takes account of age-specific death rates, and can thus yield measures of life expectancy and the extent of premature death.



## N

Nitrogen oxides 16 Compounds of nitrogen and oxygen produced by the burning of fossil fuels. No-regrets opportunities
See no-regret s policy

. No-regret options

16 Definition from www.eia.doe.gov/oiaf/1605/95report/glossary.ht ml visited on November 21, 2007.

6-11SAP 4.6 Glossary and Acronyms

See no-regrets policy

. No-regrets policy One that would generate net social benefits
whether or not there is climate change . N oregrets opportunities for greenhouse gas

emissions reduction are defined as those options whose benefits such as reduced energy costs and reduced emissions of local/regional pollutants equal or exceed their costs to society, excluding the benefits of avoided climate change. No-regrets potential is defined as the gap between the market potential and the socio-economic potential

. Non-linearity A process is called “non-linear” when there
is no simp le proportional relation between
cause and effect. The climate system contains many such non-linear processes, resulting in a system with a potentially very complex behavior. Such complexity may
lead to rapid climate change

. Non-market impacts Impacts that affect e c osystems or human welfare, but that are not directly linked to market transactions—for example, an increased risk of premature death. See also market impacts

. North Atlantic Oscillation (NAO)
The North Atlantic Oscillation consists of opposin g vari ations of barometric pressure
near Iceland and near the Azores. On average, a westerly current, between the Icelandic low pressure area and the Azores high pressure area, carries cyclones with their associated frontal systems towards Europe. However, the pressure difference
between Iceland and the Azores fluctuates

on time scales of days to decades, and can
be reversed at times. It is the dominant
mode of winter climate variability in the North Atlantic region, ranging from central North America to Europe.



## O

Ocean conveyor belt The theoretical route by which water
circulates around t he entire global ocean, driven by wind and the thermohaline
circulation

. Opportunity An opportunity is a situation or
circu m stance to decrease the gap between
the market potential of any technology or practice and the economic potential

, socioeconomic potential , or technological potential

. Opportunity costs The cost of an economic activity forgone by the choice of another activity. Ozone (O3) Ozone, the triatomic form of oxygen (O3), is
a gaseous at m ospheric constituent. In the troposphere it is created both naturally and by photochemical reactions involving gases resulting from human activities (photochemical “smog”). In high concentrations, tropospheric ozone can be harmful to a wide-range of living organisms. Tropospheric ozone acts as a greenhouse

gas . In the stratosphere , ozone is created by
the interaction between solar ultraviolet radiation and molecular oxygen (O2). Stratospheric ozone plays a decisive role in the stratospheric radiative balance . Its concentration is highest in the ozone layer

. Depletion of stratospheric ozone, due to chemical reactions that may be enhanced by climate change , results in an increased ground-level flux of ultraviolet-B radiation

. See also Montreal Protocol and ozone layer

.



## P

Parameterization

In climate models , this term refers to the technique of representing process es, that cannot be explicitly resolved at the spatial or temporal resolution of the model (sub-grid scale processes), by relationships between the area- or time-averaged effect of such sub-grid-scale processes and the larger scale
flow. Pareto criterion/Pareto optimum A requirement or status that an individual’s
welfare could not be f u rther improved without making others in the society worse
off.

6-12SAP 4.6 Glossary and Acronyms

Particulates Very small solid exhaust particles emitted during the co mbustion of fossil and biomass fuels. Particulates may consist of a wide variety of substances. Of greatest concern for health are particulates of less than or equal to 10nm and 2.5 nm in diameter, usually designated as PM10 and PM2.5, respectively. Pathogen 17 An agent that causes disease, especially a living microorganism such as a bacterium or fungus.
Permafrost Perennially frozen ground that occurs
wherever the te mperature remains below 0°C for several years. Photochemical smog A mix of photochemical oxidant air pollutants pro duced by the reaction of sunlight with primary air pollutants, especially hydrocarbons. Point-source pollution Pollution resulting from any confined,
discrete sourc e , such as a pipe, ditch, tunnel, well, container, concentrated animal feeding operation, or floating craft. See also nonpoint-source pollution

. Present value cost The sum of all costs over all time periods,
with future costs discount ed. Projection (generic) A projection i s a potential future evolution of a quantit y or set of quantities, often computed with the aid of a model. Projections are distinguished from “predictions” in order to emphasize that projections involve assumptions concerning, for example, future socio-economic and technological developments that may or may not be realized, and are therefore subject to
substantial uncertainty . See also climate projection and climate prediction

. Proxy

17 The American Heritage® Dictionary of the English Language, Fourth Edition . Retrieved November 21, 2007, from Dictionary.com
website: http://dictionary.reference.com/browse/pathogen A proxy climate indicator is a local record that is interpreted, using physical and biophysical principles, to represent some
combination of climate-related variations
back in time. Climate-related data derived in this way are referred to as proxy data. Examples of proxies are tree ring records, characteristics of corals, and various data
derived from ice cores.



## Q

QALY (Quality Adjusted Life Year) 18
A measure of the outcome of actions (either individual or treatment interventions) in terms of their health impact. If an action gives a person an extra year of healthy life expectancy, that counts as one QALY. If an action gives a person an extra year of unhealthy life expectancy (partly disabled or in some distress), it has a value of less than
one. Death is rated at zero.

Quality of Life 19 A scientific measure of personal well-being. Categories used to define place-specific quality of life include the inter-related categories of economic conditions; natural resources, environment, and amenities; human health; public and private infrastructure; government and public safety; and social and cultural resources.



## R

Radiative forcing Radiative forcing is the change in the net vertical irradiance (express ed in Wm -2) at
the tropopause due to an internal change or a change in the external forcing of the climate system , such as, for example, a change in the concentration of carbon
dioxide or the output of the Sun. Usually radiative forcing is computed after allowing

18 Definition taken from http://www.aihw.gov.au/publications/health/ah9 6/ah96-x04.html visited on November 21, 2007.

19 Definition modified from text within Chapter 5
of this document.

6-13SAP 4.6 Glossary and Acronyms

for stratospheric temperatures to readjust to radiative equilibrium, but with all tropospheric properties held fixed at their unperturbed values. Range shifts Climate change-induced changes in the geographical distributio ns of plants, ani mals and ecosystems Rapid climate change
The non-li nearity of the climate syste m may lead to rapid climate change , sometimes called abrupt events or even surprises. Some such abrupt events may be imaginable, such as a dramatic reorganization of the
thermohaline circulation , rapid deglaciation, or massive melting of permafrost leading to fast changes in the carbon cycle . Others may be truly unexpected, as a consequence of astrong, rapidly changing, forcing of a nonlinear system.
Reference scenario
See baseline/refer ence. Reinsuranc e The transfer of a portion of primary insurance risks to a secondary tier of insurers (reinsurers); essentially “insurance
for insurers.”
Relative sea level Sea level measured by a tid e gauge with respect to the land upon which it is situated.
See also Mean Sea Level

. Revealed pre ference 20 The use of the value of expenditure to "reveal" the preference of a consumer or group of consumers for the bundle of goods they purchase compared to other bundles of equal or smaller value.
Reservoir A component of the climate syst em , other
than the atmosphere , that has the capacity to store, accumulate or release a substance of concern (e.g., carbon or a greenhouse gas ). Oceans, soils, and forests are examples of
carbon reservoirs. The term also means an artificial or natural storage place for water, such as a lake, pond or aquifer , from which

20 Definition http://wwwpersonal.umich.edu/~alandear/glossary/r.html visited on November 21, 2007. the water may be withdrawn for such purposes as irrigation or water supply.
Resilience Amount of change a system can undergo
without chan ging state. Response ti me The response time or adjustment time is the
time needed fo r the climate system or its components to re-equilibrate to a new state, following a forcing resulting from external and internal processes or feedbacks . It is very different for various components of the climate system. The response time of the troposphere is relatively short, from days to weeks, whereas the stratosphere comes into equilibrium on a time scale of typically a few months. Due to their large heat capacity, the oceans have a much longer response time, typically decades, but up to centuries or millennia. The response time of the strongly coupled surface-troposphere system is, therefore, slow compared to that of the stratosphere, and mainly determined by the
oceans. The biosphere may respond fast (e.g., to droughts ), but also very slowly to imposed changes. See lifetime for a different definition of response time pertinent to the rate of processes affecting the concentration of trace gases.
Rodent-borne disease 21 Disease that is transmitted between hosts by
a rodent (e.g. bubonic plague, hantavirus).
Runoff That part of precipitation that does not
evaporate and is not transpired

.



## S

Salinization
The accumulation of salts in soils.
Salmonella 22

21 Definition modified from definition of vectorborne disease.

22 Definition modified from information on the
CDC’s website: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/sal monellosis_g.htm#What%20sort%20of%20germ %20is%20Salmonella visited on November 21,
2007.

6-14SAP 4.6 Glossary and Acronyms

There are many different kinds of Salmonella bacteria. They pass from the feces of people or animals to other people or
other animals and can cause diarrheal illness
in humans. Salmonella has been known to cause illness for over 100 years. They were discovered by a American scientist named Salmon, for whom they are named.
Saltwater intrusion/encroachment Displacement of fresh surface water or

groun d water b y the advance of saltwater due to its greater density, usually in coastal
and estuarine areas. Scenario (generic) A plausible and often simplified description of how the future may develop, based on a
coherent and internally consistent set of assumptions about key driving forces (e.g., rate of technology change, prices) and relationships. Scenarios are neither predictions nor forecasts and sometimes may be based on a “narrative storyline.” Scenarios may be derived from projections

, but are often based on additional
information from other sources. See also
SRES scenarios

, climate scenario , and

emission scenarios

. Sea-level rise
An increase in the mean level of the ocean.
Eustatic sea-l e vel rise is a change in global average sea level brought about by an
alteration to the volume of the world ocean.
Relative sealevel rise occurs where there is a
net increase in the level of the ocean relative
to local land movements. Climate modelers largely concentrate on estimating eustatic sea-level change. Impact researchers focus on relative sea-level change.
Seawall A human-made wall or embankment along a shore to prevent wave eros ion

. Semi-arid regions Ecosystems that have m o re than 250 mm precipitation per year but are not highly productive; usually classified as rangelands

. Sensitivity Sensitivity is the degree to which a system is affected, either adversely or beneficially, by
climate-related stimuli . The effect may be direct (e.g., a change in crop yield in response to a change in the mean, range, or variability of temperature) or indirect (e.g., damages caused by an increase in the frequency of coastal flooding due to sealevel rise ). See also climate sensitivity

. Sequential decision making Stepwise decision making aiming to identify
short-ter m strategies in the face of long-term uncertainties, by incorporating additionalinformation over time and making midcourse correc tions. Sequestratio n The process of increasing the carbon content
of a carbon reservoir other than the atmosphere . Biological approaches to sequestration include direct removal of
carbon dioxide from the atmosphere through land-use change

, afforestation

, reforestation , and practices that enhance soil carbon in agriculture. Physical approaches include separation and disposal of carbon dioxide from flue gases or from processing fossil fuels to produce hydrogen- and carbon dioxide-rich fractions and longterm storage in underground in depleted oil and gas reservoirs, coal seams, and saline aquifers

. See also uptake

. Sink Any process, activity or mechanism that

re m oves a greenhouse gas , an aerosol , or a

precursor of a greenhouse gas or aerosol
from the atmosphere

. Smog 23 Air pollution typically associated with
oxidants. Snowpacks A seasonal accumulation of slow-melting

snow. Social cost The social cost of an activity includes the
value of all the resourc es u sed in its provision. Some of these are priced and others are not. Non-priced resources are
referred to as externalities. It is the sum of the costs of these externalities and the priced

23 Definition from The U.S. EPA’s Terms of Environment Glossary at http://www.epa.gov/OCEPAterms/sterms.html visited on November 21, 2007.

6-15SAP 4.6 Glossary and Acronyms

resources that makes up the social cost. See
also private cost and total cost

. Social indicators 24
Broad, standardized measures of the quality
of life or other socio-economic conditions of geographic areas such as nations, metropolitan areas, or other areas; used to assess health conditions, educational levels, food availability, violence, and other
conditions.
Socio-economic scenarios
Scenarios concerning futu re conditions in terms of population, Gross Domestic
Product and other socio-economic factors relevant to understanding the implications of climate change . See SRES scenarios.
Source Any process, activity, or mechanism that
releas es a greenhouse gas , an aerosol , or a

precursor of a greenhouse gas or aerosol
into the atmosphere

. Southern Oscillation
See El Niño Southern Oscillation

. Spatial and temporal scales
Climate m ay vary on a large range of spatial
and tem poral scales. Spatial scales may range from local (less than 100,000 km2), through regional (100,000 to 10 million km2) to continental (10 to 100 million km2). Temporal scales may range from seasonal to geological (up to hundreds of millions of years).
SRES scenarios
SRES scenarios are emissions scenarios developed b y Nakicenovic et al . (2000) and used, among others, as a basis for the climate projections in the IPCC WGI contribution to the Third Assessment Report (IPCC, 2001a). The following terms are relevant for a better understanding of the
structure and use of the set of SRES
scenarios: (Scenario) Family : Scenarios that have a similar demographic, societal, economic, and technical-change storyline . Four scenario families comprise the SRES scenario set: A1, A2, B1, and B2.

24 Definition from http://srmdc.net/glossary.htm#s visited on November 21, 2007. (Scenario) Group : Scenarios within a family that reflect a consistent variation of the storyline. The A1 scenario family includes four groups designated as A1T, A1C, A1G, and A1B that explore alternative structures of future energy systems. In the Summary for Policymakers of
Nakicenovic et al (20 00), the A1C and A1G groups have been combined into one “Fossil-Intensive” A1FI scenario group. The
other three scenario families consist of one group each. The SRES scenario set reflected in the Summary for Policymakers of
Nakicenovic et al . (2000) thus consist of six
distinct scenario groups , all of which are equally sound and together capture the range of uncertainties associated with driving
forces and emissions.
Illustrative Scenario : A scenario that is
illustrative for each of the six scenario

groups reflected in the Summary for Policymakers of Nakicenovic et al . (2000). They include four revised scenario markers
for the scenario groups A1B, A2, B1, B2,
and two additional scenarios for the A1FI and A1T groups. All scenario groups are equally sound. (Scenario) Marker : A scenario that was originally posted in draft form on the SRES website to represent a given scenario family

. The choice of markers was based on which of the initial quantifications best reflected the storyline, and the features of specific models. Markers are no more likely than other scenarios, but are considered by the SRES writing team as illustrative of a particular storyline. They are included in
revised form in Nakicenovic et al . (2000).
These scenarios have received the closest scrutiny of the entire writing team and via the SRES open process. Scenarios have also
been selected to illustrate the other two scenario groups

. (Scenario) Storyline : A narrative description of a scenario (or fa m ily of scenarios) highlighting the main scenario characteristics, relationships between key driving forces, and the dynamics of their
evolution.
Stabilization

6-16SAP 4.6 Glossary and Acronyms

The achievement of stabilization of atmospheric concentrations of one or more greenhouse gases (e.g., carbon dioxide or a CO2-equivalent basket of greenhouse gases).
Stakeholder A person or an organization that has a legitimate interest in a project or entity, or would be affected b y a particular action or policy. Stated preference 25 Stated preference approaches, sometimes referred to as direct valuation approaches, are survey methods that estimate the value individuals place on particular non-market goods based on choices they make in hypothetical markets Stimuli (climate-related)
All the elements of climate change

, including m e an climate characteristics, climate variability , and the frequency and magnitude of extremes. Storm surge The temporary increase, at a particular locality , in the height of the sea due to

extrem e meteorological conditions (low atmospheric pressure and/or strong winds). The storm surge is defined as being the excess above the level expected from the tidal variation alone at that time and place. Storyline
See SRES scenarios

. Streamflow Water within a river channel, usually expressed in m 3 sec-1. Stratosphere The highly stratified region of the atmosphere above the troposphere extending fro m about 10 km (ranging from 9 km in high latitudes to 16 km in the tropics on average) to about 50 km. Submergence
A rise in the water level in relation to the land, so that a reas of for merly dry land become inundated; it results either from a sinking of the land or from a rise of the
water level.
Subsidence

25 Definition taken from SAP 4.6. The sudden sinking or gradual downward settling of the Earth’s surface with little or
no horizontal motion. Subsidy Direct payment from the government to an
entit y , or a tax reduction to that entity, for implementing a practice the government wishes to encourage. Greenhouse gas

emissions can be reduced by lowering existing subsidies that have the effect of raising emissions, such as subsidies to fossilfuel use, or by providing subsidies for practices that reduce emissions or enhance
sinks (e.g., for insulation of buildings or planting trees). Sustainable development Development that meets the needs of the present without com p romising the ability of future generations to meet their own needs.



## T

Technology A piece of equipment or a technique for perform ing a particular activity.
Thermal erosion
The erosion of ice-rich permafrost by the
combined thermal and mechanical action of moving water. Thermal expansion In connection with sea level, this refers to
the increase i n volume (and decrease in density) that results from warming water. A warming of the ocean leads to an expansion
of the ocean volume and hence an increase
in sea level.
Thermohaline circulation Large-scale density-driven circulation in the ocean, caused by differences in temperature and salinity. In the North Atlantic, the
thermohaline circulation consists of warm surface water flowing northward and cold deepwater flowing southward, resulting in a net poleward transport of heat. The surface water sinks in highly restricted sinking regions located in high latitudes.
Threshold The level of magnitude of a system process at which sudden or rapid ch ange occurs. A point or level at which new properties

6-17SAP 4.6 Glossary and Acronyms

emerge in an ecological, economic or other system, invalidating predictions based on mathematical relationships that apply at
lower levels.
Time-series studies 26 Studies done using a set of data that expresses a particular variable measured
over time. Top-down models The terms “top” and “bottom” are shorthand for aggregate and disaggregated m odels. The top-down label derives from how modelers applied macro-economic theory and econometric techniques to historical data on consumption, prices, incomes, and factor costs to model final demand for goods and services, and supply from main sectors, like the energy sector, transportation, agriculture, and industry. Therefore, top-down models evaluate the system from aggregate economic variables, as compared to bottomup models that consider technological options or project specific climate change mitigation policies. Some technology data were, however, integrated into top-down analysis and so the distinction is not that
clear-cut.
Total cost All items of cost added together. The total cost to society is made up of bot h the
external cost and the private cost , which together are defined as social cost

. Trade effects Economic impacts of changes in the purchasing p o wer of a bundle of exported goods of a country for bundles of goods imported from its trade partners. Climate policies change the relative productio n costs and may change terms of trade substantially enough to change the ultimate economic
balance. Transient climate response The globally averaged surface air

te m perature increase, averaged over a 20- year period, centered at the time of CO2 doubling (i.e., at year 70 in a 1% per year

26 Definition modified from the definition of time-series data from the Millennium Ecosystem Assessment, 2005. compound CO2 increase experiment with a global coupled climate model ). Troposphere The lowest part of the atmosphere fro m the
surface to ab out 10 km in altitude in midlatitudes (ranging from 9 km in high latitudes to 16 km in the tropics on average) where clouds and “weather” phenomena occur. In the troposphere, temperatures generally decrease with height.
Tundra A treeless, level, or gently undulating plain
characte ristic of arctic and subarctic regions.



## U

Uncertainty An expression of the degree to which a value (e.g., the future state of the climate
syste m ) is unknown. Uncertainty can result
from lack of information or from disagreement about what is known or even knowable. It may have many types of sources, from quantifiable errors in the data to ambiguously defined concepts or terminology, or uncertain projections of human behavior. Uncertainty can therefore be represented by quantitative measures (e.g., a range of values calculated by various models) or by qualitative statements (e.g., reflecting the judgment of a team of experts). See Moss and Schneider (2000).
See also confidence and likelihood. Unique and threatened systems Entities that are confined to a relatively

narrow geogr aphical range but can affect other, often la rger entities beyond their range; narrow geographical range points to sensitivity to environmental variables, including climate , and therefore attests to potential vulnerability to climate change

. United Nations Framework Convention on Climate Change (UNF CCC) The Convention was adopted on 9 May
1992 , in New York, and si gned at the 1992 Earth Summit in Rio de Janeiro by more than 150 countries and the European Community. Its ultimate objective is the
‘stabilization of greenhouse gas
concentrations in the atmosphere at a level

6-18SAP 4.6 Glossary and Acronyms

that would prevent dangerous anthropogenic
interference with the climate system ’. It
contains commitments for all Parties. Under the Convention, Parties included in Annex I aim to return greenhouse gas emissions not controlled by the Montreal Protocol to 1990 levels by the year 2000. The Convention
entered in force in March 1994. See also Kyoto Protocol

. Urban Heat Island Effect 27

The urban heat island effect is a measurable increase in ambient urban air temperatures resulting primarily from the replacement of vegetation with buildings, roads, and other heat-absorbing infrastructure. The heat island effect can result in significant temperature differences between rural and
urban areas.
Urbanization
The conversion of land from a natural state or managed natural state (such as agriculture) to cities; a process driven by net
rural-to-urban m igration throug h which an increasing percentage of the population in any nation or region come to live in
settlements that are defined as “urban
centers”.



## V

Valley Fever (Coccidiomycosis) 28 An infectious respiratory disease of humans and other animals caused by inhaling the fungus Coccidioides immitis. It is characterized by fever and various respiratory symptoms. Also called coccidiomycosis.
Valuation 29

27 Definition from the U.S. Environmental Protection Agency’s Heat Island Glossary, http://www.epa.gov/hiri/r esources/glossary.html #h, visited on November 21, 2007.

28 The American Heritage® Dictionary of the English Language, Fourth Edition

. Retrieved November 21, 2007, from Dictionary.com
website: http://dictionary.reference.com/browse/valley
fever.

29 Definition taken from the glossary of the Millenium Ecosystem Assessment, 2005. The process of expressing a value for a particular good or service in a certain context (e.g., of decision-making) usually in terms of something that can be counted,
often m oney , but also through methods and measures from other disciplines (sociology, ecology, and so on). See also Values.
Value added The net output of a sector after adding up all outputs and subtracting int ermediate inputs. Value of a statistical life (VSL) 30 The sum of what people would pay to reduce their risk of dying by small amounts that, together, add up to one statistical life.
Values Worth, desirability, or utility based on
indivi dual pre ferences. The total value of any resource is the sum of the values of the
different individuals involved in the use of the resource. The values, which are the
foundation of the estimation of costs, are measured in terms of the willingness to

pay (WTP) by individuals to receive the resource or by the willingness of individuals to accept payment (WTA) to part with the

resource. Vector An organism, such as an insect, that

transm its a pathogen from one host to
another. See also vector-borne diseases

. Vector-borne diseases Disease that is transmitted between hosts by

a vector organism such as a mosquito or tick (e.g., malaria

, dengue fever , and leishmaniasis). Volatile Organic Compounds (VOCs) 31 Organic compounds that evaporate readily
into the air. VOCs include substances such as benzene, toluene, methylene chloride, and methyl chloroform. Vulnerability The degree to which a system is susceptible

to, or unable t o cope with, adverse effects of climate change , including climate variability and extremes. Vulnerability is a function of the character, magnitude, and rate of climate

30 Definition taken from SAP4.6.

31 Definition from ATSDR’s Glossary of Termsat http://www.atsdr.cdc.gov/glossary.html#G-Tvisited on November 21, 2007.

6-19SAP 4.6 Glossary and Acronyms

variation to which a system is exposed, its sensitivity , and its adaptive capacity

. collective basis. The constituents of wellbeing are commonly cons idered to include materials to satisfy basic needs, freedom and choice, health, good social relations, and security. 

## W

Well-being 34 Water consumption A context- and situation-dependent state,

co m prising basic material for a good life,freedom and choice, health and bodily wellbeing, good social relations, security, peace of mind, and spiritual experience. Amount of extracted water irretrievably lost during its use (by evaporat ion and goods production).Water consumption is equal to
water withdrawal minus return flow.
Water stress West Nile virus 35 A country is water-stressed if the available freshwater supply relative to water withdrawals acts as an important constraint on development. Withdrawals exceeding 20% of renewable water supply has been
used as an indicator of water stress. West Nile virus (WNV) is a single-stranded
RNA virus of the fam ily Flaviviridae, genus Flavivirus. The main lifecycle of WNV is
between birds and insects. Humans are most often infected by a bite from an infected mosquito. Most people infected with WNV don’t show any symptoms, whereas those that do are often diagnosed with West Nile Fever which can last up to two weeks. Water-use efficiency Carbon gain in ph otosynthe sis per unit water
lost in evapotranspiration . It can be expressed on a short-term basis as the ratio of photosynthetic carbon gain per unit transpirational water loss, or on a seasonal
basis as the ratio of net primary production or agricultural yield to the amount of
available water. 

## Z

Zoonoses Diseases and infections which are naturally

transm itted between verteb rate animals and people. See also zoonotic disease. Water withdrawal
Amount of water extracted from water
bodies. Zoonotic disease
Waterborne diseases 32 A disease that normally exists in other vertebrates but also infects humans, such as dengue fever, avian flu, west Nile virus and bubonic plague. Diseases contracted through contact with
water that is i n fected with any of numerous pathogens including Vibrio cholerae

, Campylobacter

, Salmonella, Shigella, and the diarrheogenic Escherichia coli.
Watershed 33 The land area that drains into a particular watercourse or body of water. Sometimes used to describe the dividing line of high ground between two catchment basins.
Welfare
An economic term used to describe the state of well-being of hum ans on an indi vidual or

32 Definition modified from information on
CDC’s website http://www.cdc.gov/ncidod/dbmd/diseaseinfo/wa terbornediseases_t.htm visited on November 21,
2007. 34 Definition modified from the Millenium Ecosystem Assessment, Current State and Trends Assessment Glossary, 2005

35 Definition modified from information on http://www.cdc.gov/ncidod/dvbid/westnile/index
.htm 33 Definition taken from the glossary of the Millenium Ecosystem Assessment, 2005.

6-20SAP 4.6 Glossary and Acronyms



### 6.2 Acronyms

AAG Association of American Geographers

AAP American Academy of Pediatrics

AIACC Assessment of Impacts and Adaptations t o Climate Change

AMR-A North American Region

CCP ICLEI’s Cities for Climate Protection

CCSP Climate Change Science Program

CDC Center for Disease Control

CLIMB Climate’s Long-Term Impacts on Metro Boston

CO 2 Carbon Dioxide

CVD Cardiovascular Disease

DHS Department of Homeland Security

ECHAM4 A model named after the European Centre for Medium Range Weather Forecasts (ECMR W F), (giving it the first part of the name – EC), which was developed in Hamburg (HAM)

ENSO El Niño/Southern Oscillation

EPA Environmental Protection Agency

FDA Food and Drug Administration

FEMA Federal Emergency Management Agency

GCM General Circulation Model

GDP Gross Domestic Product

GIS Geographic Information Systems

GISS NASA Goddard Ins titute for Space Studies

ICLEI International Council for Local Environmental Initiatives

IPCC Intergovernmental Panel on Climate Change

MA Millennium Assessment

MM5 Mesoscale Model

MSA Metropolitan Statistical Areas NAAQS National Ambient Air Quality Standards

NACC U.S. National Assessment of Climate Change

NAS National Academy of Sciences

NAST National Assessment Synthesis Team

NEG/ECP New England Governors and Eastern Canadian Premiers

NGO Non-Governmental Organization

NO Nitric oxide

NOAA National Oceanic and Atmospheric Administration

NRC National Research Council

NYCHP New York Climate and Health Project

PM Particulate Matter

PM2.5 Particulate Matter (smaller than 2.5 micrometers)

PTSD Post-Traumatic Stress Disorder

RADM2 Regional Acid Deposition Model, Version 2

RCM Regional Climate Model

RMNP Rocky Mountain National Park

SAP Synthesis and Assessment Products

SRES Special Report on Emissions Scenarios

TBE Tick-borne Encephalitis

6-21SAP 4.6 Glossary and Acronyms

UHI Urban Heat Island Effect

UNDP United Nations Development Programme

UNEP United Nations Environmental Programme

U.S. BEA United States Bureau of Economic Analysis

USDA U.S. Department of Agriculture

USGCRP United States Global Cha n ge Research Program

VBZ Vector Born and Zoonotic

VEMAP Virtual Earth Map

VOC Volatile Organic Matter

VSL Value of Statistical Life

WHO World Health Organization

WTP Willingness to Pay

6-22Contact Information

Global Change Research Information Office c/o Climate Change Science Program Office 1717 Pennsylvania Avenue, NW
Suite 250 Washington, DC 20006 202-223-6262 (voice) 202-223-3065 (fax) The Climate Change Science Program incorporates the U.S. Global Change Research Program and the Climate Change
Research Initiative. To obtain a copy of this document, place an order at the Global Change Research Information Office (GCRIO) web site: http://www.gcrio.org/orders

Climate Change Science Program and The Subcommittee on Global Change Research

William J. Brennan, Chair Department of Commerce National Oceanic and Atmospheric Administration Acting Director, Climate Change Science Program

Jack Kaye, Vice Chair National Aeronautics and Space Administration

Allen Dearry Department of Health and Human Services

Anna Palmisano Department of Energy

Mary Glackin National Oceanic and Atmospheric Administration

Patricia Gruber Department of Defense

William Hohenstein Department of Agriculture

Linda Lawson Department of Transportation

Mark Myers U.S. Geological Survey

Jarvis Moyers
National Science Foundation

Patrick Neale
Smithsonian Institution Jacqueline Schafer U.S. Agency for International Development

Joel Scheraga Environmental Protection Agency

Harlan Watson Department of State

Executive Office an d other Liaisons

Stuart Levenbach Office of Management and Budget

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Katharine Gebbie National Institute of Standards & Technology

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Gene Whitney Office of Science and Technology Policy