CLIMATE CHANGE IMPACTS IN

THE MID-ATLANTIC REGION –

A WORKSHOP REPORT
CLIMATE CHANGE IMPACTS IN THE

MID-ATLANTIC REGION –

A WORKSHOP REPORT

The Pennsylvania State University

Nittany Lion Inn

September 9-11, 1997

Compiled by Ann Fisher, Eric Barron, Brent Yarnal,

C. Gregory Knight, and James Shortle

Edited by Ann Fisher and Ron Smart

Sponsored by The U.S. Environmental Protection Agency,

Office of Research and Development,

Global Change Research Program

(Cooperative Agreement No. CR 826554-01),

and Office of Policy

(Cooperative Agreement No. CR 824369-01)

and The Pennsylvania State University
TABLE OF CONTENTS

Executive Summary............................................................................................................ 3

Preface ................................................................................................................................. 7

Chapter 1: Setting the stage

The Mid Atlantic Region’s Geography and People (Colin Polsky).......................... 9

Climate Variability in the Mid-Atlantic Region (Brent Yarnal) ............................. 14

Projecting Climate Change (Eric Barron)............................................................... 24

Chapter 2: In what ways is the Mid-Atlantic Region especially vulnerable

to climate change and variability?

Introduction ........................................................................................................... 37

Potential impacts of climate variability and change

in the Mid-Atlantic region ................................................................................ 39

- Economic growth, industry and commerce ................................................ 39

- Ecosystems.................................................................................................. 41

- Water resources and water quality .............................................................. 43

- Agriculture, forestry and fisheries............................................................... 45

- Recreation ................................................................................................... 46

- Natural hazards/extreme events ................................................................. 47

- Human health ............................................................................................. 48

Reducing vulnerability ........................................................................................... 50

Chapter 3: Improving Resiliency and Capturing Opportunities: How can we

manage our resources to respond to climate change and adapt to variability?

Introduction ........................................................................................................... 53

Identifying near-term adaptation strategies............................................................. 55

- Economic growth, industry and commerce ................................................ 55

- Ecosystems.................................................................................................. 57

- Fresh water quantity and quality ................................................................ 58

- Agriculture, forestry and fisheries............................................................... 59

- Recreation ................................................................................................... 61

- Natural hazards/extreme events ................................................................. 62

- Human health ............................................................................................. 62
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Chapter 4: What kinds of research are needed most to help the region

respond and adapt to climate change?

Introduction ........................................................................................................... 65

Diverse research needs............................................................................................ 65

- Economic growth, industry and commerce................................................ 65

- Ecosystems.................................................................................................. 66

- Water resources: quantity and quality ........................................................ 67

- Agriculture, forestry and fisheries .............................................................. 68

- Natural hazards........................................................................................... 69

- Human health............................................................................................. 70

Moving toward a research agenda........................................................................... 71

Chapter 5: Synthesis, Conclusions and Next Steps

Introduction ........................................................................................................... 73

Four questions........................................................................................................ 73

- What do we know about the impacts of climate change

in the watersheds of the Chesapeake and Delaware Bays? .................... 73

- What strategies can be considered now for reducing vulnerability and

taking advantage of opportunities presented by climate change?.......... 75

- What else do we need to know?.................................................................. 75

- How do we make sure the new knowledge is useful for

and available to the region’s decision-makers? ...................................... 76

Next steps and update............................................................................................. 78

Appendix

Web site.................................................................................................................. 82

Steering Committee Members................................................................................ 83

List of Participants ................................................................................................. 84

Working group questions....................................................................................... 88

Workshop Agenda.................................................................................................. 90

Letter from Vice President Gore ............................................................................ 93
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CLIMATE CHANGE IMPACTS IN THE MID-ATLANTIC REGION –

A WORKSHOP REPORT

EXECUTIVE SUMMARY

PURPOSE

Recognizing that global climate change will be felt differently by people depending on

where they live, Vice President Gore and the Office of Science and Technology Policy

(OSTP) encouraged the U.S. Global Change Research Program (USGCRP) to initiate a

series of workshops in 1997. The purpose of these regional workshops was to examine

climate change issues within regions and to obtain information for analysis of climate

change impacts at the national scale.

A spectrum of interested parties from academia, industry, government, and

environmental organizations convened to address impacts of climate change in the MidAtlantic region, focusing on the watersheds of the Chesapeake and Delaware Bays. Small

groups worked to: (a) identify potential climate impacts in the context of other stresses on

the region, (b) ascertain what is known now and what needs to be known in order to

make informed decisions in response to opportunities and challenges posed by climate

variability and change, and (c) suggest early actions for addressing the potential impacts of

climate variability and climate change. These working groups relied on three background

papers, presentations during plenary sessions, and their own expertise.

Pennsylvania State University (Penn State) was asked by the U.S. Environmental

Protection Agency (EPA) USGCRP to host the Mid-Atlantic Workshop, held September

9-11, 1997.

The Region’s Unique Characteristics

The Mid-Atlantic Region has several characteristics that make its people, economy,

and ecosystems sensitive to climate change. These include:

• Extensive shorelines

• Significant agricultural, forest, and fishery sectors

• A large population

• Historical settlement patterns along waterways

• An economy based on abundant water

• Unique natural resources, such as the Chesapeake Bay
4

The region also has features that may help to make is resilient to climate change.

These include:

• A highly developed, diversified, dynamic economy.

• Significant potential to adapt through technological and institutional change

MAJOR FINDINGS

• The Mid-Atlantic Region is reasonably robust with respect to climate variability.

This conclusion is based on factors such as the region's abundant water resources,

varied ecosystems, diversified economy, and history of managing weather-related

disasters. Working groups representing different sectors (economic growth, industry

and commerce; ecosystems; water resources; natural hazards; human health;

agriculture, forestry and fisheries) potentially vulnerable to climate impacts ranked

climate low in importance relative to factors such as poverty, global market pressures,

and water and air quality. They viewed these other factors as presenting more

immediate, tangible impacts.

• Climate change could have adverse impacts on the region’s people, economy, and

ecosystems. When working groups accepted model-based future climates as indicative

of the future, climate impacts took on greater importance. Some impacts were judged

to be as important as other major issues that influence the region’s economic and

societal well-being.

• Potential impacts could vary widely by sector depending on the sensitivity of the

sector and the potential for adaptation. The working groups that discussed health,

ecosystems, and recreation expected profound effects in these sectors. Significant sea

level rise would have a marked and extensive impact in the Mid-Atlantic area. In

contrast, the working group for agriculture did not consider this highly adaptable

component of the regional economy to be seriously threatened under the climate

change scenarios. Global markets are likely to be a greater driver for agriculture than

climate. Similarly, the region’s economic growth was not viewed as seriously

threatened under the climate change scenarios adopted for the workshop. This

conclusion largely reflects the group’s expectation that the regional economy’s size,

diversity, and adaptability make it resilient with respect to the impacts of climate

change. On the other hand, impacts could be substantial and important on a local

scale. This working group expressed uncertainty about how factors governing

economic growth, such as water availability and transportation infrastructure, might

be affected by climate change.

• The importance of climate change in influencing the severity or frequency of

natural disasters is unclear. In general, working groups could identify the types of
5

vulnerabilities, but were unable to assess their magnitudes given the uncertainties

inherent in future climate predictions.

RECOMMENDATIONS

The uncertainties highlighted in the background papers and presentations and in the

working group and summary discussions led to three types of recommendations: research

needs, education and communication needs, and near-term strategies for adaptation to

climate variability and change.

Research Needs:

The scientific information available for assessing regional impacts of climate change

and variability is extremely limited. Assessments based on this limited information could

grossly miscalculate either the threat or opportunities to the region. Essential information

for improving the assessment of how the Mid-Atlantic region would be affected by climate

change include:

• how climate change will affect the regional climate (i.e., frequency and intensity of

severe weather, the nature and timing of precipitation events, frequency and

severity of droughts);

• the rate and magnitude of climate change at the scale of public and private decision

makers in climate sensitive sectors (e.g., agriculture, forestry, water supply);

• how climate change will affect the region’s natural resources and ecosystems;

• how climate change will affect the productivity of agriculture, forests, fisheries and

other sectors;

• differences in risk between private and public sector activities;

• differences in risk for different population segments;

• the role of information in initiating responses to minimize risks or maximize

opportunities;

• how institutional and technological change can diminish risks and enhance

opportunities;

• the current state of Mid-Atlantic ecosystems, and the associated monitoring and

modeling of ecosystem changes; and

• expected regional demographic changes.
6

Education and communication:

Essential needs include:

• enhancing environmental education within medical training, and

• ensuring that the nature of climate predictions and their uncertainties are wellarticulated and widely available to the full spectrum of interested parties.

Near-term strategies:

Actions can be taken now to address problems that are already recognized or that

represent a “win-win” approach to climate impacts. These include:

• enforcing restrictions on construction and eliminating subsidies for rebuilding in

flood-prone areas,

• expanding the use of urban heat warning systems,

• developing flexible water management across regional or local districts, and

• improving land-use and drought planning.

While many strategies can be conceived that would reduce existing and expected

stresses, some would have high economic or societal costs. For example, enhancing the

infrastructure for water management through increased storage capacity is logical given

the Mid-Atlantic region’s propensity to drought. But the region needs to consider the

environmental implications of dams and reservoirs along with their construction and

operating costs. Thus additional analysis can examine the cost effectiveness of proposed

strategies to address current stresses likely to increase because of expected economic and

population growth. Such actions offer benefits of reducing the region’s vulnerability to

climate as a bonus.
7

PREFACE

Recognizing that global climate change will be felt differently by people depending on

where they live, Vice President Gore and the Office of Science and Technology Policy

(OSTP) encouraged the U.S. Global Change Research Program (USGCRP) to initiate a

series of workshops in 1997. The purpose of these regional workshops was to examine

climate change issues within regions and to obtain information for analysis of climate

change impacts at the national scale. The objectives were to:

- increase understanding of high priority regional environmental issues for which

climate change is likely to be important;

- increase understanding of the region’s vulnerability to climate variability and

climate change;

- identify how individuals, governments and industry in the region currently cope

with environmental stresses, including climate stresses (e.g., droughts and floods);

- identify future coping mechanisms and options for adjustment and adaptation;

- identify existing information and research needed to reduce vulnerability and

improve adjustment and adaptation options;

- define a preliminary, prioritized research agenda for the region;

- define follow-on activities in the region;

- initiate regional analyses to support national assessments of climate change impacts.

Pennsylvania State University (Penn State) was asked by the U.S. Environmental

Protection Agency (EPA) USGCRP to host the Mid-Atlantic Workshop, held September

9-11, 1997. Aided by consultation with a 17-member Steering Committee (listed in

Appendix), the organizing committee set up an agenda (see Appendix). The 92 invited

participants represented federal, state and local government, industry, academia, and

public interest groups.

By the end of the workshop, participants reported becoming more informed about

climate change and its potential for regional impacts. They were enthusiastic about

education and information dissemination, especially for reducing uncertainties about

climate variability– at scales fine enough to help water managers and farmers with their
8

planning. They expressed strong concerns about potential impacts from sea-level rise on

ecosystems and recreation and about human health impacts.

The workshop was sponsored by the U.S. Environmental Protection Agency (EPA)

and by the following Penn State units: Earth System Science Center (ESSC) and Center

for Integrated Regional Assessment within the College of Earth and Mineral Sciences,

Department of Agricultural Economics & Rural Sociology and the College of Agricultural

Sciences, Environmental Resources Research Institute, and Office of Research.

Many individuals contributed to the success of this workshop. EPA’s Joel Scheraga,

Mike Slimak, Susan Bassow and Anne Grambsch provided vital assistance when the

decision was made to add the Mid-Atlantic region to the first round of regional

workshops, and Scheraga contributed an excellent public address when, at the last minute,

Vice President Gore could not come. Wanda Haxton navigated EPA’s paperwork

channels on a short time schedule. Our Steering Committee provided valuable feedback

on drafts of the background papers and suggestions about whom to invite and how to

make the agenda most effective.

Special thanks to Richard Horan for his contribution to the third background paper

and to developing pre- and post-workshop questionnaires, to Jeff Carmichael for

coordinating the cadre of graduate students who summarized the plenary and working

group sessions, and to Patti Anderson for constructive suggestions on the draft report.

The administrative assistance provided by Deb Detwiler, Linda Spangler and Lori Lynch,

was superb and contributed to the success of the workshop. Phil Kolb set up the web page

report (www.essc.psu.edu/ccimar), which has been maintained and updated by Mary

Easterling.

The workshop’s most important component was the hard work put in by the

participants. Rapporteur Baruch Fischhoff noted that participants became readier to

engage in the network being built, so that the Mid-Atlantic region can make smarter

decisions related to impacts from climate change. Many of those participants now serve

on the Advisory Committee for the First Mid-Atlantic Regional Assessment of Impacts

from Climate Change (MARA); others are collaborating with MARA’s large Penn State

team. We look forward to continued interaction with stakeholders as we proceed. While

at OSTP, Jerry Melillo stressed that the regional workshops could be a first step toward

more systematic thinking by the region’s citizens about planning for a sustainable future.

As co-chair of the National Assessment Synthesis Team, he continues to see the regional

assessments as providing a framework for smart decisions about the future. We agree.

Ann Fisher, Eric Barron, Brent Yarnal, C. Gregory Knight, James Shortle

(Organizing Committee)

February 1999
9

CHAPTER 1: SETTING THE STAGE

THE MID-ATLANTIC REGION’S GEOGRAPHY AND PEOPLE,

BY COLIN POLSKY

A. INTRODUCTION

An assessment of likely regional impacts from climate change begins with the baseline

setting, including the region’s climate and the natural and human environments. For the

Mid-Atlantic Region (hereafter MAR; cover and Figure 1), historical climate is outlined in

Yarnal (this document). The natural and human environments and their changes over the

past three decades are described below. This brief, general profile of the region provides

context for the analyses that follow.

Figure 1. The Mid-Atlantic Region and its sub-regions.

The MAR as defined for this assessment of climate change impacts includes all of the

Chesapeake Bay and Delaware River drainage basins. These basins include all or parts of

232 counties in New York, Pennsylvania, New Jersey, Delaware, Maryland, Virginia,

West Virginia, and the District of Columbia, and cover approximately 277,000 km2

(112,000 square miles). For the purposes of this analysis, the MAR is divided into four

physiographic regions, or areas of similar landforms (Tarbuck and Lutgens, 1996; Miller,

1995). Table 1 relates the size of these regions relative to the greater MAR. In all, the
10

MAR covers about 3 percent of the land area in the 48 contiguous United States (U.S.

Bureau of Census, 1997).

Table 1. The Mid-Atlantic Region at a Glance

Counties Surface Area

Coastal Plain 72 52,376 km2

Piedmont 54 57,360 km2

Ridge & Valley 54 59,227 km2

Appalachian Plateau 52 107,919 km2

Mid-Atlantic Region 232 276,882 km2

Source: NPA, 1998.

B. THE NATURAL ENVIRONMENT

The Physiographic Regions

The relatively flat coastal plain is composed mostly of sedimentary rock and extends

inland from the oceans and estuaries. This zone traverses all of Delaware and parts of

New Jersey, Maryland and Virginia. The piedmont plateau is the foothills region covering

the eastern, lower portion of the Appalachian Mountain range, which is composed mostly

of metamorphic and igneous rock and found in north-central New Jersey, southeastern

Pennsylvania and in the central portions of Virginia and Maryland.

The MAR ridge and valley zone has folded terrain with a series of parallel, eroded

mountains. This strip of land extends from the northwest corner of New Jersey to the

southwest, passing through Pennsylvania, Maryland and Virginia. A notable part of this

zone is the so-called blue ridge region, the extended, thin ridges of the Appalachian

Mountains– including the highest points of that range– located primarily in Virginia and

Maryland, with smaller representations in Pennsylvania and New Jersey. The

Appalachian plateau describes a swath of land from the New York portion of the MAR

through northern and western Pennsylvania, the western edge of Maryland and most of

West Virginia. This region is composed mostly of relatively flat sedimentary rock,

dissected in many places by meandering waterways (Tarbuck and Lutgens, 1996; Miller,

1995).
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Land Use and Land Cover

The MAR has two principal types of land cover, forest and agricultural lands (U.S.

EPA, 1997). (Certain MAR counties in New York and New Jersey are not included in

these land cover calculations.) These two categories account for almost all of the land

cover in the MAR, with forest cover being the leading category. The highest

concentrations of forest area are in and around West Virginia and north-central

Pennsylvania; agriculture is the predominant land use in the lowlands to the east of the

Appalachians. About 5 percent of the MAR is classified as federal land (U.S. Bureau of the

Census, 1997).

All MAR watersheds have at least half of their total stream length in forest cover,

reflecting a reasonable safeguard against agricultural runoff and other pollution to water

sources (U.S. EPA, 1997). However, all MAR watersheds also have some agriculture

operations and many have roads located near the streams, indicating a potential for

considerable, if diffuse, risk for water pollution (U.S. EPA, 1997). For instance, twothirds of the nutrient and sediment loading in the Chesapeake Bay comes from upstream

and non-point sources. This pollution is long-lived: the Chesapeake Bay flushing rate, at

about 350 days, is one of the slowest rates for a water body in the United States (NOAA,

1998).

C. THE HUMAN ENVIRONMENT

The People

Tables 2 and 3 show recent trends and geographic distributions of the MAR

population and economy. Approximately 34.5 million people live in the MAR (1996

estimate; Table 2), representing about 13 percent of the entire U.S. population (NPA,

1998; U.S. Bureau of the Census, 1998b). More than three-fourths of the total MAR

population, income and jobs are concentrated in the coastal plain and piedmont, where the

large urban agglomerations are found. This density translates into a markedly higher per

capita income for these two sub-regions compared to the Ridge & Valley and Appalachian

Plateau sub-regions. This concentration also reflects the importance of the Atlantic

Ocean, Chesapeake Bay, and the Delaware and Susquehanna Rivers for regional food,

employment, energy and recreation. While large cities do not cover much of the MAR

surface area, collectively they constitute one of the more important population

concentrations in the country. Of the MAR urban areas, Philadelphia, Pittsburgh,

Baltimore, Washington, D.C., Richmond and Norfolk are among the largest cities in the

U.S., accounting for more than half of the total MAR population (U.S. Bureau of the

Census, 1998a).
12

Table 2. Geographic Distribution of Key Socio-Economic Variables

for the Mid-Atlantic Region: 1996 (Percent and Value)

Coastal Plain Piedmont Ridge & Valley Appalachian

Plateau

MAR

Totals

Population

(million people)

49%

17.0

28%

9.6

11%

3.7

12%

4.2

100%

34.5

Income

(billion 1992$)

52%

$428

30%

$251

9%

$72

10%

$79

100%

$829

Income per Capita

(1992$) $22,047 $21,678 $18,014 $17,427 $19,987

Total Employment

(million jobs)

52%

10.6

27%

5.4

11%

2.2

10%

2.1

100%

20.3

Total Farm Employment

(thousand jobs)

19%

34.3

31%

56.8

26%

46.4

24%

44.1

100%

181.6

Source: NPA, 1998.

Table 3. Changes in Key Socio-Economic Variables

for the Mid-Atlantic Region: 1967-1996

Total Change Average Annual Change

Population 28% 0.9%

Income 139% 3.1%

Income per Capita 91% 2.3%

Total Employment 71% 1.9%

Total Farm Employment -36% -1.5%

Source: NPA, 1998.

The MAR population increased by approximately 28 percent during the past three

decades, slightly less than 1 percent per year on average (Table 3). This trend resembles

that for the nation as a whole, which grew by 33 percent at an annual rate of 1 percent

(U.S. Bureau of the Census, 1998b). Total regional personal income grew by about 140

percent over this period, and per capita income almost doubled. Income in the service

sector recorded significant growth over the period (over 300 percent), such that services,

government and manufacturing presently account for nearly one-half of all regional

income (NPA, 1998). Total employment has increased by about 70 percent since 1967,

fueled largely by non-farm industries such as services, which more than doubled over the
13

period. On the other hand, farm-related employment fell by more than one-third. When

combined with the growth in services and other sectors, this reduction in farm

employment points to a diminished economic role for agriculture in the region, similar to

the larger national trend.

REFERENCES CITED:

Miller, E.W., ed., 1995. A Geography of Pennsylvania. The Pennsylvania State University

Press: University Park, Pennsylvania.

National Oceanic and Atmospheric Administration (NOAA), 1998. Our Crowded Shores:

Balancing Growth and Resource Protection. CD-ROM produced by the National Ocean

Service and InterNetwork Media, Inc.

NPA, 1998. “Regional Economic Projections Series.” NPA Data Services, Inc.:

Washington, D.C.

Tarbuck, E.J and F.K. Lutgens, 1996. Earth: An Introduction to Physical Geology, 5

th

Edition. Prentice Hall: Upper Saddle River, New Jersey.

U.S. Bureau of the Census, 1997. 1997 Statistical Abstract of the United States.

Washington, D.C. URL: http://www.census.gov/prod/3/97pubs/97statab/cc97stab.htm.

U.S. Bureau of the Census, 1998a. State and Metropolitan Area Data Book 1997-98 (5th

Edition). Washington, D.C.

U.S. Bureau of the Census, 1998b. Historical National Population Estimates. URL:

http://www.census.gov/population/estimates/nation/popclockest.txt.

U.S. EPA, 1997. An Ecological Assessment of the United States Mid-Atlantic Region: A

Landscape Atlas. Office of Research and Development. Washington, D.C. Document

#EPA/600/R-97/130.
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CLIMATE VARIABILITY IN THE MID-ATLANTIC REGION,

BY BRENT YARNAL

A. INTRODUCTION

One way to estimate how a region will react to future global climate change is to study

how the region has been affected by past climate variations. Before determining (1) what

we already know about past climate variations in the Mid-Atlantic Region and (2) what we

need to learn, it is important to clarify some basic definitions and facts about climate,

climate change, and climate variability.

Although climate is often thought of as average weather, it is much more than that.

Weather is the hour-to-hour and day-to-day state of the atmosphere. In contrast, climate

encompasses the longer-term condition of the atmosphere. Climate reflects the frequency

and intensity of weather experienced at a time and place, including storms, cold outbreaks,

and heat waves.

The climate system varies and changes because of the atmosphere's interaction with

the total Earth system of water, rock, soil, and life. This variation and change includes the

commonplace daily and seasonal cycles and short-term extreme events such as floods and

droughts, as well as long-term episodes such as wet and dry decades, cool or warm

centuries, and glacial-interglacial cycles.

There is much confusion over the terms climate variation and climate change.

However, for the United Nations Convention on Climate Change, scientists, decisionmakers, and other stakeholders have resolved that climate variation refers to natural

variation in climate, while climate change pertains to those variations in climate

attributable to human activity. These human activities– such as industrial operations or

land transformations– influence the planetary energy balance by emitting or leading to the

creation of the radiatively active gases carbon dioxide, methane, nitrous oxide, and the

halon family, or by injecting microscopic particles into the atmosphere. Radiatively active

gases enhance the natural greenhouse effect and are believed to be warming the planet,

while microscopic particles screen out incoming sunlight and cool the surface.

Climate change arises from human activity, but climate variation is the result of

natural forces operating at different time scales. The two most fundamental variations in

climate are day and night and the seasons, which result from relationships between the sun

and Earth on time scales of days and years, respectively. The third most important

identified variation in the climate system is El Niño-Southern Oscillation (ENSO) events,

which perturb the global oceanic and atmospheric circulations and can produce droughts

and floods in certain regions. For example, during warm phases of ENSO (known as El
15

Niño), the southern United States tends to be very wet and may suffer floods; during

ENSO cold phases (known as La Niña), this region is prone to drought. These extremes

of ENSO usually occur every three to five years and last for about a year and a half.

Scientists are developing the ability to predict these events and their regional patterns of

flood and drought many months in advance. Many other causes of variability on seasonal

to interannual time scales, such as volcanic eruptions, are difficult to predict.

Climate also varies on time scales ranging from decades to millions of years. Decadelong variations result from interactions among the different components of the Earth

system (atmosphere, ocean, land, biosphere, and ice). Because each of these components is

characterized by different response times, their interactions produce climate variations on

many different time scales. Decade-long variations can also result from variations in solar

output tied to sunspot cycles. On century time scales, planetary warming and cooling

may be caused by long-term oscillations in solar output. In the last two to three million

years and on time scales of ten thousand years or more, variations in Earth's orbit around

the Sun may have been responsible for more than 20 glacial-interglacial cycles. Even

longer-term changes in the configuration of the continents and associated mountainbuilding episodes result in climate variations over ten million years or more, such as the

ice age conditions of the last 35 million years or the generally warm Earth inhabited by

the dinosaurs.

Climate varies over space as well as time. In any given year or decade, the climate in

one region may be anomalously warm, cool, wet, or dry, while temperature and

precipitation in an adjacent region may be close to average. Climate patterns in some

regions may be particularly sensitive to phenomena such as ENSO.

A regional understanding of climate variation is important because biophysical and

human impacts are felt regionally, rather than globally. In the United States, storms,

floods, heat waves, droughts, and cold outbreaks are regional phenomena, although their

impacts may be serious enough to spread throughout the nation and the world. For

example, the 1988 drought so devastated the Midwest that it had a measurable influence on

the national and world economies.

Understanding regional climate variation and its impacts is crucial to understanding

climate change. There is uncertainty about how climate change will influence specific

regions, but many scientists think that it will be felt primarily through regional climate

variations. Some regions may suffer more frequent and intense droughts, for instance,

while others may have fewer and weaker droughts. Either way, because regional

variations in climate are normal, it may be difficult for individuals, including scientists, to

distinguish anthropogenic climate change from natural climate variation. Current

scientific efforts are aimed at determining what climate change plus natural variability

would look like at a regional scale.
16

As a first step in understanding how climate variation affects the Mid-Atlantic Region’s

climate today and may influence it in the future, this section first addresses seasonal and

decadal climate variations observed in the region during the past century. Then it looks at

the region's longer-term climate variations of the last 1000 years. It concludes by

summarizing what we know about climate variation in the Mid-Atlantic Region and what

we need to learn.

B. RECENT CLIMATE VARIATION IN THE MID-ATLANTIC REGION

There is a wealth of observed climate data– that is, data recorded by weather

instruments– for the Mid-Atlantic Region. However, the relatively short period of these

data provides insight only on recent climate variations of years and decades; assessment of

longer time scales of climate variation require data sets of greater length. To deduce longer

time-scale variations or to determine how climate varied before the invention of weatherrecording instruments, it is necessary to reconstruct climates by recovering and

interpreting natural phenomena and human artifacts containing climate information.

Section C below discusses the reconstruction of pre-instrumental climate in the MidAtlantic Region.

The National Climatic Data Center (NCDC) has monthly data for Mid-Atlantic

Region temperature, precipitation, and Palmer Drought Severity Index (PDSI). The PDSI

is important to agriculture because it tracks soil-moisture conditions. These three

variables extend back to 1895 and are presented here for the Mid-Atlantic Region (see

Figure 2), defined by the watershed boundaries of the Chesapeake and Delaware Bays.

The figure shows that the temperature, precipitation, and PDSI of the Mid-Atlantic

Region have varied substantially on annual and decadal time scales over the last century.

These surface climate variations can be linked to variations in the region's atmospheric

circulation.

Precipitation

The Mid-Atlantic Region appears to have experienced three distinct precipitation

regimes during the last century; each was separated by a period with sharply reduced

precipitation. The first regime extended from the beginning of the record until about

1930. With few exceptions, precipitation totals were below the long-term average. This

period ended in the early 1930s when the driest period in the last century contributed to a

sharp, but short-lived precipitation deficit. The second regime started when precipitation

rose to slightly above average totals. This regime ended with the 1960s, when nearly every

year was well below average. In 1970, the third regime began when precipitation totals
17

took a dramatic jump, with all but a few years in the last 27 being above normal. Many of

these years were very wet; the wettest year in the record is 1996.

Figure 2. Departures from long-term (1895-1996) average monthly precipitation (inches), annual

temperature (° Fahrenheit), and annual Palmer Drought Severity Index for the Mid-Atlantic

Region. The dashed line denotes average annual values, while the bold, solid line is a five-year

running average.
18

Temperature

From the beginning of the record until the late 1920s, Mid-Atlantic Region

temperatures were well below the long-term average (although a few years during this

period had noticeably above-normal temperatures). Then, except for a couple of

conspicuous cold years, temperatures from the late 1920s until about 1960 were well above

average. Note that from the beginning of the record to the mid-1950s, there was a marked

warming trend. This trend ended when temperatures started to drop in the mid-1950s,

falling well below average by the 1960s and staying there (except for a few years in the mid

1970s) until approximately 1980. Since then, temperatures have oscillated above and

below normal, with a couple of remarkably hot years in 1988 and 1989.

Palmer Drought Severity Index

Except for several moist years in the 20th century's first decade, this index was well

below the long-term average (i.e., conditions were dry) until the mid-1930s. The last few

years of this period – the infamous Dust Bowl years in the Great Plains– were

exceptionally dry. The succeeding period from the mid-1930s until the early 1960s tended

to be moist. The 1960s were very dry, while the 1970s were extraordinarily wet. The

period from the 1980s through the first half of the 1990s was the only time in the 102-year

record that precipitation oscillated around the normal mark. The Mid-Atlantic Region

droughts of 1980, 1986, 1988, and 1991 are evident. Also remarkable is the sharp spike at

the end of the record caused by the exceptionally wet year 1996.

Relationship to atmospheric circulation variations

There are clear relationships among the Mid-Atlantic Region's precipitation,

temperature, and PDSI variations of the last century. In general, from the beginning of

the record to about 1930, the climate was cool and dry. The early 1930s saw a couple of

exceedingly hot, dry years associated with the midwestern Dust Bowl. This short, sharp

drought was replaced by nearly three decades of relatively warm, moist climate. This

period was replaced by a cool and very dry climate in the 1960s. In contrast, the 1970s

were exceedingly wet, but varied between warm and cold. Since the late 1970s-early 1980s,

temperature and precipitation have varied above and below normal.

These variations in regional climate since World War II can be explained by changes in

the atmospheric circulation. (Earlier periods lack the jet stream-level data needed to make

the following generalizations.) A zonal regime dominated the atmospheric flow over

North America through the late 1940s and early 1950s. (Note: a zonal flow regime means

that the jet stream over the United States tends to flow from west to east, with few of the
19

north-south excursions that produce ridges of warm air and troughs of cool air. In

contrast, during periods of meridional flow, the jet stream has a much greater north-south

amplitude, often producing a big ridge of warm sub-tropical air over the western United

States and a deep trough of polar air over the eastern half of the nation.) Such a regime

produced normal to slightly above-normal temperatures and variable precipitation over

the Mid-Atlantic Region. Then in the mid- to late 1950s, the circulation experienced a

change from zonal to meridional flow; a stable meridional-flow regime was fully

entrenched by the 1960s. During this decade, the Mid-Atlantic Region tended to be

influenced by an anomalous, deep trough of continental polar air, a storm track southeast

of its long-term mean position, and precipitation often falling off the Atlantic coast. This

regime promoted a relatively cool, dry climate. The early 1970s saw the continuation of

this meridional regime, but the trough migrated westward, putting the average position of

the storm track over the Mid-Atlantic Region. This change caused a significant increase in

precipitation. Finally, the mid- to late- 1970s brought a large change in the atmospheric

circulation. The period following this change– which has extended to the present– has

been associated with significant increases in the interannual variability of the atmospheric

circulation, with unusually large variations in the shape and positioning of the month-tomonth and year-to-year jet stream flow over North America. Such major variations in

circulation have produced a highly variable surface climate.

Recent Mid-Atlantic Region climate extremes

Current trends suggest a change towards a less extreme Mid-Atlantic Region climate.

The last frost of spring is tending to come progressively earlier, while there are fewer very

cold winter days. These changes imply that the region’s winters are warming. At the

same time, the number of very hot summer days appears to be decreasing (although there

is some question about the reliability of these data). Although many experts think that

human-induced climate change will bring more extreme climate to most regions, it is

possible that the above trends could be the realization of climate change in the MidAtlantic Region.

Comparison to nation and globe

How do the Mid-Atlantic Region variations discussed above compare to rest of the

United States and the world? Comparable, but different, interannual and decadal

variations in temperature and precipitation have been detected in all regions of the United

States. Scientists have found that average air temperature in the United States warmed by

about 0.7°F over the last century. However, that increase was not linear, and not all areas

of the country warmed. The nation was relatively cool until the 1930s, at which time

temperatures rose sharply. Temperatures fell during the 1950s to 1970s, with sharpest

declines during the 1960s. Temperatures rose again in the 1970s and have remained high

since then. These patterns roughly coincide with the temperature trends for the Mid-
20

Atlantic Region, although the area has warmed more during the century than the national

average. Variations in global surface temperature observations also roughly correspond to

those of the Mid-Atlantic Region, with the region warming more than the global average

of approximately 0.5-1°F.

Precipitation variations for the United States also show surprising resemblance to the

Mid-Atlantic Region variations. Notably, since about 1970, precipitation has tended to

remain above the 20th century mean and has averaged about 5% more than in the earlier

part of the record. Some of the largest precipitation increases over the century occurred

over the Mid-Atlantic Region, especially the northern parts of the Chesapeake and

Delaware Bay drainage areas. Globally, precipitation over land has gone up 1% during the

20th century. However, global precipitation has been relatively low since about 1980,

which does not correspond with Mid-Atlantic Region and United States observations.

The 1960s drought in the Mid-Atlantic Region shows up in the national PDSI record,

but is overshadowed by the great midwestern droughts of the 1930s and 1950s. Perhaps

more important, similar to the Mid-Atlantic Region record, the United States has tended

to be unusually wet since approximately 1970. PDSI is not calculated globally, so it is

difficult to make comparisons with the Mid-Atlantic Region record for this variable.

Finally, has the global atmospheric circulation matched the variations noted over

North America and the Mid-Atlantic Region? The behavior of the equatorial Pacific

ENSO phenomenon has been unusual since the mid-1970s, especially since 1989. During

that time, El Niño events have been more frequent and persistent than La Niña. These

findings can partly explain the behavior of the atmospheric circulation over North

America and the Mid-Atlantic Region since the mid-1970s, but cannot account for

variations in the circulation and regional climate before then. Research suggests that these

earlier variations were related to changes in the extratropical North Pacific and North

Atlantic, not the equatorial Pacific.

C. THE CLIMATE OF THE LAST 1000 YEARS

Long records of climate variations are needed so that scientists can compare the natural

variation of the period before the Industrial Revolution with the mixed natural and

anthropogenic climate signal observed since then. Unfortunately, comprehensive climate

observations are restricted to the last century and a half, and to even shorter periods in

many regions. Consequently, pre-instrument (paleoclimate) climate variations must be

deduced from proxy data for climate-sensitive phenomena, such as tree rings, corals,

glacier ice cores, and alpine glacier advance and retreat. Chronologies for quantitative data

can also be culled from historical records, such as journals and tax and mercantile records.

The data from the last 1000 years are especially important because they are relatively
21

abundant and fresh and because the variations they portray are most relevant to the

current climate.

Although tree ring data are the most plentiful of the natural proxy data, they are still

too sparse to provide a complete global picture over time. Ice core, coral, and glacier

advance-retreat data are even less common. Thus, the majority of the data for the last

millennium may reflect regional, rather than global climate signals.

Despite these data problems, glacier ice cores and a variety of other paleoclimate

reconstructions show that globally the 20th century has been warmer than any century

since 1400 AD, and is probably the warmest century in the last 1000 years. Furthermore,

some evidence suggests that this century is perhaps as warm as any comparable period in

the last 10,000 years– that is, since the retreat of the continental glaciers from North

America and Eurasia. On century time scales, it has also been estimated that the

variability of global mean temperature over the last millennium has been less than ±0.9°F.

The temperature increase that coincided with the end of the Industrial Revolution may

soon exceed this range. It is important to note that century-scale climate data suggest that

natural variation can be abrupt and large.

Knowledge of Mid-Atlantic Region climate since the mid-17th century is based

primarily on reconstructions using tree rings and historical data from diaries, newspapers,

and periodicals. These and other data suggest that until the late 19th century, the region

was cool and somewhat wet, but was affected by individual years of intense drought and

occasional decades of prolonged drought. Overall, the year-to-year and decade-to-decade

climate was highly variable and not unlike that observed in the latter 20th century. After

about 1880, the area warmed gradually. Climate variation decreased until the latter 20th

century. For the entire record, the longest drought extended from about 1850-1873,

although the most severe prolonged drought occurred in the 1960s. The reconstruction

evidence suggests that ENSO events have a significant effect on the hydrology of the MidAtlantic Region, although comprehensive work on this subject has yet to be done. In

general, the climate patterns from these paleoclimate reconstructions are consistent with

other regions of the eastern United States and the North Atlantic basin.

D. CONCLUSIONS

Climate varies on many space and time scales, with regional variations at interannual,

decadal, and century time scales being of most immediate importance to society. Knowing

how a region’s climate has varied in the past provides a baseline against which future

regional climate change can be compared.

Analysis of the Mid-Atlantic Region’s climate shows that variations have been

considerable. For example, each year in the 1960s was cool and very dry, while the 1970s
22

possessed a more variable temperature regime, but were very wet. Other decades, such as

the 1980s and first half of the 1990s, were distinguished by relatively extreme year-to-year

variation in all climate variables. These interannual and decadal climatic variations were

closely associated with the atmospheric circulation over the region, and were also related

to United States and global variations. Longer time scales of climate variation for the MidAtlantic Region are only crudely documented and understood, but some facts are known.

For instance, the 1960s appear to have been the driest decade of the last few centuries,

while the extreme interannual climate variation of the 1980s and 1990s are not

unprecedented.

Despite its ecological and socioeconomic importance (and the concentration of

climatologists that live in the region), the Mid-Atlantic Region’s climate variation is

surprisingly poorly understood. Yet, to determine if climate is changing, and to discern

how climate affects the region’s ecosystems and society, it is crucial that such an

understanding be improved. Thus, more research is needed on interannual, decadal, and

century-scale climate variation of the Mid-Atlantic Region. Specifically, research that

promotes clearer answers to the following questions should be addressed:

• Is the Mid-Atlantic Region climate becoming warmer or cooler, wetter or drier, or

more variable or extreme?

• Are these trends consistent with trends observed in other regions or globally?

• Are these trends unusual? That is, are these trends consistent with previous

variations experienced in the region, or are they suggestive of human-induced

climate change?

REFERENCES CITED:

Baron, W.R., 1995. Historical climate records from the northeastern United States, 1640

to 1900. In, Climate Since A.D. 1500, R.S. Bradley and P.D. Jones, editors. Routledge,

London: 74-91.

Cook, E.R., and G.C. Jacoby, 1977. Tree-ring drought relationships in the Hudson

Valley, New York. Science, 198: 399-401.

Cook, E.R., and G.C. Jacoby, 1983. Potomac River streamflow since 1730 as

reconstructed from tree rings. Journal of Climate and Applied Meteorology, 22:

1659-1672.

DeGaetano, A.T., 1996. Recent trends in maximum and minimum temperature threshold

exceedences in the Northeastern United States. Journal of Climate, 9: 1646-1660.
23

Guttman, N.B., and R.G. Quayle, 1996. A historical perspective of U.S. climate divisions.

Bulletin of the American Meteorological Society, 77: 293-303.

Houghton, J.T., L.G. Meiro Filho, B.A. Callander, N. Harris, A. Kattenberg, and K.

Maskell (editors), 1996. Climate Change 1995 – The Science of Climate Change.

Cambridge University Press, Cambridge.

Karl, T.R., R.W. Knight, D.R. Easterling, and R.G. Quayle, 1996. Indices of climate

change for the United States. Bulletin of the American Meteorological Society, 77:

279-292.

Yarnal, B., and B. Frakes, 1997. Synoptic Climatological Atlas of the Northeastern

United States. Northeast Regional Climate Center, Cornell University, Ithaca, NY.

Yarnal, B., and D.J. Leathers, 1988: Relationships between interdecadal and interannual

climatic variations and their effect on Pennsylvania climate. Annals of the Association of

American Geographers, 78: 624-641.
24

PROJECTING CLIMATE CHANGE,

BY ERIC J. BARRON

A. INTRODUCTION

To what extent will the human-induced increases in greenhouse gases and atmospheric

aerosols influence future climate? The answer to this question has become linked to issues

of economic vitality and national security because of potential impacts from climate

change on natural ecosystems, agriculture, water resources, human health, energy

utilization and human migration. The record of observations based on meteorological

instruments is too short to determine the degree to which humans are responsible for the

general warming trend over the last century. The only recourse to answer this question is

to construct mathematical models of the Earth system and attempt to predict future

change. Climate models are the principal tools available to predict how the climate will

respond to increases in greenhouse gases. These models point to significant global

warming, with large changes in the continental water balance, over the next decades and

centuries. In every case, the climate models suggest that the familiar global and regional

environments on which society has come to depend are in danger of changing. Many of

the predictions imply serious stresses on society and have prompted discussion of

sometimes costly mitigation and adaptation response measures. Are the predictions of

climate models accurate enough to warrant such measures?

The complexity of the climate system is a major obstacle to predicting the details of

future climate change. Neither the physical relationships described by climate models nor

the available climatological observations are sufficient to project with certainty how

climate will change. Consequently, society is left with a difficult decision. What steps

should we take when the best predictions from state-of-the-science models suggest that

climate change due to human activities will be large and significant, yet the predictions

themselves have large uncertainties? The scientific debate over these uncertainties has

truly entered the public arena, providing considerable confusion even in cases where the

conclusions from climate models are robust. To be useful for policy development, the

degree of certainty associated with the different elements of climate predictions must be

evaluated and ranked. The credibility of the full range of climate model predictions must

be described in order to elucidate the aspects of climate model predictions that are highly

uncertain as well as those that are robust. Such an analysis not only guides policy

development but focuses attention on the areas of research that are most likely to benefit

society. Accurate long-term climate forecasts would most certainly have tremendous

economic value.
25

B. A FOUNDATION FOR DISCUSSION

Many aspects of future global change, and particularly the topic of global warming, are

far less controversial in scientific circles than they are in public discussion. For each of the

following seven points there is no real credible debate or controversy. These points,

which are based on a spectrum of scientific investigations, provide foundation and context

for discussions of future climate change.

First, laboratory experiments demonstrate that greenhouse gases– also referred to as

radiatively important gases– absorb and re-emit energy in the infrared wavelengths emitted

by the Earth’s land, oceans, and clouds. The most important of these so-called greenhouse

gases are water vapor, carbon dioxide, methane, and nitrous oxide.

Second, because of their infrared absorption, increased concentrations of greenhouse

gases exert a global warming influence. The role of greenhouse gases as agents to promote

warming is not in question; rather the issues of uncertainty involve only the timing and

the magnitude of the warming.

Third, the atmospheric concentrations of carbon dioxide, methane, nitrous oxides, and

chlorofluorocarbons are significantly above their pre-industrial levels. These increases can

be tied directly to human activities involving fossil fuel consumption, deforestation,

agriculture, and some industrial processes.

Fourth, carbon dioxide levels are now about 30% above pre-industrial levels. A

draw-down of carbon dioxide to near its pre-industrial level would take centuries even if

emissions were substantially reduced in the near future. This conclusion stems from the

fact that the sinks (e.g., deep ocean) for carbon dioxide operate on long time scales. In

addition, since substantial reduction in global carbon dioxide emissions below current

levels is unlikely over the next decades, atmospheric concentrations of carbon dioxide are

expected to continue to increase.

Fifth, atmospheric aerosol (dust and soot) concentrations are also significantly

increased in source regions over pre-industrial levels. The primary natural sources include

windblown dust, hydrocarbons from vegetation and forests, and soot from forest and

grassland fires. Increased aerosol concentrations are also found downwind from regions of

high fossil fuel combustion and biomass burning.

Sixth, laboratory and atmospheric measurements demonstrate that sulfate aerosols

from volcanic eruptions and from fossil fuel combustion exert a cooling influence on the

climate. However, the magnitude, trends, and extent of induced cooling effects are

uncertain.
26

Seventh, global average surface air temperatures are about 0.4-0.6°C (~1°F) higher

than average temperatures in the nineteenth century. Because of natural variations in

climate, this warming cannot yet be attributed definitively to human activities. Although,

recently the Intergovernmental Panel on Climate Change (1996) agreed that there is a

discernable effect of anthropogenic greenhouse gases on climate.

These seven conclusions indicate that scientists have a strong basis for stating that

human activities are modifying the energy balance of the Earth system. The uncertainties

center on the magnitude, timing and distribution of the associated climate changes. It is

these three characteristics of climate model predictions that are the subject of considerable

debate.

C. CLIMATE MODEL PREDICTIONS FOR THE FUTURE

Mathematical simulations or models of the atmosphere and ocean systems are the

primary tools used to predict the future response of the climate system. The most

sophisticated models are called General Circulation Models (GCMs), which attempt to

include a comprehensive treatment of the physics that govern the behavior of the

atmosphere and oceans. These models are designed to calculate changes in the winds,

temperatures, pressures and moisture budget given a specific set of “external” boundary

conditions. External boundary conditions represent any specified variable, like the

position of the continents, the amount of energy received by the sun, or the composition

of the atmosphere. The power of these models lies in their ability to simulate systems that

are too complex for simple, intuitive reasoning. The models are not without limitation.

Obviously not every molecule of the atmosphere can be incorporated into a model. Since

they are computationally very intensive, many simplifications are employed– one of

which is to simulate the climate at a very coarse spatial resolution (for example the

Susquehanna River Basin may be represented by only one or two grid points in a global

climate model). In other cases, complex relationships such as the characteristics of land

vegetation are turned into simple functions designed to approximate these relationships.

The key is to incorporate all of the critical processes and feedbacks, while maintaining a

tractable model.

We have a growing number of independently derived GCMs. These models have become

the basis for intercomparisons as a means of evaluating the potential range of future

climate change. More and better observations are available to test the capabilities of the

model predictions and, with increased knowledge about how the climate system operates,

we can provide a more critical assessment of climate model predictions. Figure 3 provides

the range of predicted changes in global-mean surface temperature for the next eighty

years from seven different GCMs, each assuming an increase in carbon dioxide of one

percent per year (the standard scenario for the Intergovernmental Panel on Climate

Change). Figure 4 gives an example from one model (Manabe and Stouffer, 1994) of the
27

increase in annual-mean global surface temperatures predicted for a doubling of the

present day amount of atmospheric carbon dioxide 50 to 100 years from now. This figure

shows the coarse resolution of the global model predictions, while suggesting that the

Mid-Atlantic States will be 4 to 5°C (7-9°F) warmer than at present. The predicted change

is large. For context, the summer heat wave of 1988 was less than 1°C warmer than

average in the Mid-Atlantic Region.

Figure 3. The range of predicted changes in global-mean surface temperature, in

degrees C, for the next eighty years, shown as a band bounded by the upper and

lower extremes of seven different GCMs, each of which assumed an increase of 1

percent per year in CO2

Figure 4. An example of the expected geographical distribution of an increase in

annual-mean global surface temperature that would result from a doubling of the

present amount of CO2 in the atmosphere. Contours are in degrees C. From the

GCM simulation of S. Manabe and R.J. Stouffer, Journal of Climate, vol 7, pp 5-

23, 1994, with permission of the American Meteorological Society.
28

Predictions from GCMs are imperfect because they are limited by our knowledge of

natural variability, our inability to predict future greenhouse gas and aerosol emissions

accurately, the potential for unpredicted or unrecognized factors such as volcanic

eruptions or new or unknown human influences, and our incomplete knowledge of the

climate system. With this point in mind a large group of climate modelers gathered

(USGCRP, 1995; Barron, 1995) to assess the levels of certainty associated with climate

model predictions. The intent was to provide a list, ordered by degree of certainty,

assessing the major policy-relevant predictions of climate models. This list, of necessity, is

consistent only with known facts and is based only on the “best” current knowledge.

Such a list also must include assumptions on the rate of growth of greenhouse gases. In

this case, a scenario of a 1% per year increase in the concentration of carbon dioxide is

assumed, which mimics the radiative forcing of the projected increase in the

concentrations of all greenhouse gases.

The ordered list presented below is characterized in terms of probabilities, as virtually

certain, very probable, probable and uncertain.

Virtually Certain:

(1) The increases in carbon dioxide and the decreases in stratospheric ozone will result in a

large cooling in the upper atmosphere.

Very Probable:

(2) The global mean surface temperature will increase between 0.5 to 2.0°C (0.9 to 3.6°F)

over the period of 1990 to 2050. The best estimate for a climate change resulting from a

doubling of pre-industrial carbon dioxide is a warming of 1.5 to 4.5°C, with 2.5°C being

the most probable estimate. The estimated warming will be reduced if sulfur emissions are

not controlled and the actual temperature change may even be outside the range described

here if natural climate variations are large.

(3) A warming of the surface temperature of the globe will lead to an increase in global

average precipitation because evaporation rates are closely tied to surface temperature.

(4) Northern Hemisphere sea ice will be reduced. Changes to the Southern Hemisphere

are less certain.

(5) Arctic land areas should experience amplified wintertime warming associated with the

reduction in land surface snow cover.

(6) Global warming will influence sea level. The most reasonable estimates are a sea level

rise of 5 to 40 centimeters by 2050, compared to a rise of 5 to 12 centimeters if the rates of

rise over the past century continue. These estimates ignore the long-term response of the

ice caps or any potential catastrophic collapse of the West Antarctic ice sheet, which are

the subjects of considerable debate.
29

(7) Solar variability over the next 50 years will not induce a prolonged climate forcing that

is significant in comparison with the effects of the increasing concentrations of carbon

dioxide and other greenhouse gases.

Probable:

(8) Summer Northern Hemisphere mid-latitude continental dryness will increase.

(9) The increase in the amount of atmospheric moisture will produce regions of higher

rainfall, including at high latitudes.

(10) Some regions may experience warming that is smaller than the global average,

particularly in oceanic regions where surface waters are mixed downward or where deeper

waters upwell.

(11) Historical records suggest that a few explosive volcanic eruptions are likely to occur

during the next half a century. These transient events will result in some short-term

relative cooling.

Uncertain:

(12) There is the potential for multifaceted and complicated, even counterintuitive changes

in climate variability, hence predictions of changes in climate variability are uncertain.

This aspect of climate change includes many possibilities, such as changes in winter

storminess, changes in El Niño frequencies, and variations in thunderstorms.

(13) At present, there is only very limited capability to estimate how the climate of various

regions will respond, although regional scale (from the scale of large metropolitan regions

to the scale of states) changes are likely to be different from the global average changes.

(14) An increase in tropical storm intensity is plausible due to higher sea surface

temperatures associated with global warming; however, there are too many unresolved

issues to be certain.

(15) The details of climate change over the next twenty-five years are also uncertain.

Uncertainties in the factors that control natural variability, in the model simulations, and

in the changes in atmospheric chemistry make it extremely difficult to predict or even

suggest decade-to-decade changes in climate. In any given decade, the changes in

temperature and related variables could be substantially less than or more than the trend

predicted by a climate model. Warming estimates in terms of degrees per decade and their

use to analyze a single decade are unwarranted and misleading.

(16) Climate-biosphere feedback relationships may modify the magnitude of climate

change. Whether the feedbacks will amplify or moderate climate change is not known.

The level of confidence in the results of climate model simulations depends very much

on time scale and spatial resolution. Note that the greatest confidence is assigned to ranges

predicted for the Earth as a whole and for the longer time periods over which greenhouse
30

gases will double. Regional predictions and projections on a decade-by-decade basis are far

less certain. Equally important, simulations of phenomena at very high resolution, such as

the formation of hurricanes, are also less certain. A direct implication of this assessment is

that uncertainties grow at the critical boundary where climate models intersect policy– at

the spatial and temporal resolution of climate impacts on human and ecological systems.

Yet the predictions by climate models are suggestive of substantial change with large

impacts.

D. OPPORTUNITIES FOR REDUCING UNCERTAINTIES

The ranked order of the assessment of climate model capabilities provides a framework

for focusing national and international research efforts. Over the last few decades,

progress in reducing uncertainties in climate model predictions is clear. However, the

issues and problems highlighted above are in many cases quite complex or require

long-term consistent measurements in order to reduce current uncertainties. For these

reasons, significant reductions of uncertainties in projecting changes and trends in climate

will require sustained efforts that are very likely to require a decade or more. Much of the

research effort of the U.S. Global Change Research Program and related or partner

international programs are designed to address uncertainties in cloud-radiation-water

vapor interactions, ocean circulation, aerosol forcing, natural climate variability, land

surface processes, including vegetation changes and chemical cycling, the frequency and

intensity of extreme, high impact events such as hurricanes, the potential for surprises, and

the interaction between chemistry and climate. Several areas have been identified as

priority research topics with substantial potential to reduce uncertainties over the coming

decades.

(1) Many of the uncertainties associated with climate models can be attributed to their

coarse spatial resolution. At higher resolutions, storms and circulation patterns are much

better represented. Improvements in weather forecasts suggest that intensified efforts to

tailor global predictions to specific regions using both finer-scale models and empirical

techniques will lead to significant improvements in assessing regional vulnerability to

climate change.

(2) Climate changes at the surface can be better represented by including significantly

better representations of the boundary layer between the atmosphere and the surface and

of vertical motions associated with features like thunderstorms.

(3) Substantially improved observations and representations of water vapor, a major

greenhouse gas, will reduce a major source of uncertainty in model predictions.

(4) Improvement of the linkages that couple the atmosphere, ocean, and land surface will

result in better and more comprehensive simulations.
31

(5) Better representation of the land surface, including vegetation, soil characteristics, and

carbon dioxide and ozone effects on plant function, will reduce uncertainties in estimates

of soil moisture, summertime continental drying, and in regional climate change.

(6) The development of new data sets and expectations for new, long-term, consistent

observations from NASA’s Earth Observing System, the European Space Agency and the

Japanese Space Agency, as well as current efforts to compare the full spectrum of climate

models, suggest that model comparisons against observations and other models can

accelerate the rate of model improvement.

(7) Successfully demonstrating the capability of models to simulate climates different from

the present day (i.e., past climates) would contribute substantially to our confidence in

model predictions.

(8) Changes in the concentration of non-greenhouse gases, in vegetation, and in aerosols

may indirectly influence greenhouse gases. Improving the representation of these

processes in climate models should improve prediction of climate change by incorporating

the indirect mechanisms that influence the earth’s energy budget.

Progress is occurring on all of these fronts, and research on these topics is already

yielding information of use in regional climate change assessments, which will help in

assessing climate change for the Mid-Atlantic Region.

E. HIGH-RESOLUTION PREDICTIONS OF FUTURE CLIMATE CHANGE

The coarse resolution of GCMs is identified as one of the major drawbacks for

regional assessments. For this reason, the development of high-resolution predictions is

identified above as a priority research opportunity. This importance of high-resolution

predictions is most clearly illustrated by considering precipitation. If a GCM has a spatial

resolution in which each model point is nearly the size of Pennsylvania, convective

precipitation (thunderstorms) or frontal systems are not going to be well represented.

Two innovative procedures allow us to use coarse resolution climate model predictions to

overcome this problem and assess the potential climate impacts in specific regions of the

globe. The first technique, nesting of model grids, couples global models with higher

resolution regional models. The second technique, downscaling, relates particular states of

the GCM atmosphere to specific patterns of weather at a regional level.

In model nesting, the GCM is used to compute the global circulation under conditions

different from today, for example higher carbon dioxide levels. Then the results of the

GCM (temperature, pressure, winds, moisture) are used to drive a high-resolution climate

model over a limited area. The high-resolution model includes a better representation of
32

topography and of numerous physical parameters. The promise of this technique is

demonstrated in Figure 5, in which the United States precipitation observations for spring

1980 (Figure 5a) are compared first with the prediction from a GCM (Figure 5b) and then

with the prediction from a higher resolution model nested within the GCM (Figure 5c).

Figure 5a. March, April, May 1980 observed precipitation.

Figure 5b. March, April, May 1980 GCM predicted precipitation.
33

Figure 5c. March, April, May 1980 nested GCM-mesoscale model predicted

precipitation.

In Figure 5b, the GCM’s coarse resolution is clearly evident by its failure to produce

much of the detail for the United States precipitation pattern. In Figure 5c, the results

from the same GCM simulation are portrayed, but the U.S. precipitation is derived from

the higher resolution model nested within the GCM. The high-resolution model has a

horizontal resolution of 108 km. The improvement is dramatic. The nesting technique

can also be employed using several nested grids at 36km, 12km, and 4km resolution. A

proof-of-concept experiment compared predictions of a single storm passing over the

Mid-Atlantic Region, in which the high-resolution model is driven by observations at the

boundary, and then the high-resolution model attempts to reproduce the observations.

The match is excellent. This same technique of nesting has provided a higher resolution

prediction for a doubled carbon dioxide planet. In this experiment, the Mid-Atlantic

Region is characterized by a substantially wetter winter (DJF-December, January,

February) under higher carbon dioxide conditions, but a very similar pattern of summer

(JJA - June, July, August) precipitation. Such results must be viewed with caution, as the

technique is still under critical evaluation. As yet an appraisal of strengths and weaknesses

of this technique remains a research topic.

The second technique (downscaling) assumes that the GCM is providing reasonable

large-scale predictions. Using empirical relationships derived between the observed largescale circulation and the temperature and precipitation in a region, the analysis predicts

regional climate. The formulation can be optimized by writing a model that “learns” from

trying repeated examples. Using this technique specifically for the Susquehanna River

Basin, Penn State researchers Robert Crane and Bruce Hewitson found increases in

precipitation under conditions of higher atmospheric carbon dioxide. Only March had
34

lower precipitation in comparison with present conditions. The largest increases were in

May and June.

The two techniques described above employed different GCMs and were very

different in terms of resolution and focus. Although still in their infancy, these techniques

have potential for translating global climate predictions to resolutions useful in developing

policy and examining human systems.

F. SUMMARY AND CONCLUSIONS

Three major conclusions are evident from this examination of the capabilities of

climate models. First, the radiative properties of greenhouse gases are well known, the

concentrations of these gases are increasing due to human activities, and these increases

should result in some global warming. At issue is not the fact that increases in greenhouse

gases will force climate change, but rather the magnitude and timing of the climate change.

Second, the degree of certainty associated with the results of climate models is a strong

function of both spatial and temporal detail. The greatest certainty is associated with

ranges given for global predictions. Regional predictions, predictions on a

decade-by-decade basis, and predictions of higher resolution phenomena, such as

hurricanes, are associated with much greater uncertainty in GCMs. This spectrum of

confidence associated with the level of detail that is predicted provides a reasonable guide

to policy decisions. Third, substantial opportunities, given consistent and long-term

research efforts, exist for improving climate model predictions. These opportunities

include efforts to enhance spatial resolution, to improve coupling of the components of

the climate system, and to better represent some of the indirect effects of climate change.

The nesting and downscaling techniques illustrate the potential of applying these

approaches to assessments for specific regions, such as the Mid-Atlantic Region.

The sense of the climate model simulations, while recognizing the uncertainties, is one

of significantly higher mean annual temperatures for the Mid-Atlantic Region under

doubled carbon dioxide conditions, with increased precipitation in winter. Changes in

summer precipitation appear less certain. The pattern of winter precipitation in the

Northeast appears to be significantly different, but summer precipitation patterns appear

similar to the present day. Of course, with higher temperatures, evaporation rates will

also substantially increase.

Much additional research is required to assess changes in the nature of natural

variability under higher carbon dioxide conditions, analyze the full spectrum of

hydrologic variables, compare a variety of climate model results and improve the coupling

of atmospheric models with other components of the Earth system. Future efforts must

be directed towards the research and analysis that are critical for linking climate prediction

to human endeavors.
35

Interestingly, the current focus on the policy relevance of climate models has largely

been negative: a view that climate models are far too uncertain to be used in setting costly

economic or national security policy. Certainly, the scientific debate over these

uncertainties has resulted in considerable confusion even where the conclusions from

climate models are robust. This section helps define the degree of certainty associated

with all the different elements of climate predictions in order to provide a more useful

basis for policy decisions. However, the current focus on climate models as potential

drivers of costly national policy is one-sided.

Accurate long term climate forecasts could also have tremendous economic value, as

shown by recent use of improved forecasts in limiting the impact of El Niños on food

production and fisheries in developing countries. More accurate predictions may lead to

warnings if associated with societal vulnerabilities, and will clearly contribute to economic

vitality.

REFERENCES CITED:

Barron, E.J. 1995. Climate Models: How Reliable are their Predictions. Consequences,

V.1, no.3, 16-27.

Intergovernmental Panel on Climate Change. 1996. Climate Change 1995. Cambridge

University Press.

Manabe, S. & R.J. Stouffer. 1994. Journal of Climate, V.7, 5-23.

USGCRP. 1995. Forum on Global Change Modeling. USGCRP Report 95-02, 26pp.

Washington, D.C.
36
37

CHAPTER 2: IN WHAT WAYS IS THE MID-ATLANTIC

REGION ESPECIALLY VULNERABLE TO CLIMATE

CHANGE AND VARIABILITY?

A. INTRODUCTION

Today’s climate, including heat waves, cold spells, floods, droughts, severe storms, and

other phenomena, helps determine how individuals, societies, and ecosystems function.

The human and natural worlds generally adapt to the prevailing climate and to climate

change, particularly if change is gradual. In the coming years, natural climate variation

and human-induced climate change may place increased or new pressures on natural

systems, human communities, and individuals. Even if climate change presents a more

benign future, climate may be profoundly different, thereby demanding costly

adaptations. The risks of and possible adaptations to climate variation and change are

difficult to assess because it is unclear when, where, and how climate change will be

manifest. Effects on primary production (agriculture, forests, fisheries), the economy,

water resources, human health, recreation, and the occurrence of natural hazards are

virtually certain, although the magnitude (and sometimes the direction) of these effects

remains uncertain.

This uncertainty is especially large at the regional and daily-to-annual scales, precisely

the space and time frames in which most decision-makers operate. Although they account

for the known, tangible socioeconomic and environmental stresses that exist today, many

decision-makers also need to consider the uncertain, abstract threat of climate change.

Decision-makers who know that climate influences their operations should find out if and

how climate change might affect present and future problems in their jurisdiction. They

need to know what climate impacts are possible, who is vulnerable to these impacts, and

how possible adaptation measures might reduce impacts and vulnerability. They must

assess the availability and costs of alternative adaptation strategies and consider their

priorities for implementation.

This chapter explores the Mid-Atlantic Region’s vulnerability to climate impacts, in

the context of issues such as economic growth, water resources and human health. The

next chapter considers possible regional adaptation strategies for reducing negative impacts

and taking advantage of opportunities created by climate change. It is followed by a

chapter on what we still need to learn so that the region’s citizens can make effective

decisions in the face of climate change. The concluding chapter summarizes what we

know about the potential for Mid-Atlantic climate impacts, what we need to know, how

to make sure research results are useful to the region’s decision-makers and accessible to

them, and plans for the next steps.
38

Sensitivity, adaptability, and vulnerability

The impacts of climate variation and change are a function of a system’s or an

individual’s sensitivity, adaptability, and vulnerability. Sensitivity indicates the degree to

which a system is responsive to a variation or change in climate. For example, MidAtlantic states’ ski resorts are sensitive to within-winter and year-to-year variations in

snowfall. It is possible that climate change will mean shorter snow seasons on average and

more years with no appreciable snowfall. Thus, these resorts are sensitive to the impacts

of climate change. Adaptability defines the extent to which individual or systemic

adjustments are possible in response to climate variation or change; such adaptations can

be reactive or planned. For instance, Mid-Atlantic Region temperatures are still low

enough during most winters with low snowfall to permit regional resorts to produce

artificial snow. Such an adjustment is planned. If future winter temperatures were to

become too high, this technical adaptation would not work. Vulnerability delimits the

extent to which climate may damage or harm individuals or systems. Vulnerability

depends on both sensitivity and adaptability. To complete the skiing example, the most

vulnerable ski resorts are those that are especially sensitive to snowfall variations or that

cannot adapt by making snow (e.g., the owners cannot afford snow-making machines, or

the organizational structure prevents management from reacting quickly enough to

climate).

In 1995, the Intergovernmental Panel on Climate Change (IPCC) Working Group on

Impacts, Adaptations, and Mitigation of Climate Change concluded:

• Climate impacts are difficult to establish and quantify at the regional scale because

model projections are too coarse and uncertain.

• If future climate variations extend beyond documented impacts of past climate

variations, then it is likely that actual impacts will include surprises.

• Most systems are sensitive to both the magnitude and rate of climate variation and

change.

• Climate variation and change add an important stress, especially on individuals and

systems that are most sensitive and least adaptable to climate.

• Most systems are subject to multiple climatic and non-climatic stresses.

• Vulnerability increases as adaptive capacity decreases.

• Successful adaptation depends on technological advances, institutional

arrangements, availability of financing, and information exchange.

• Enhanced support for research and monitoring is essential.
39

B. POTENTIAL IMPACTS OF CLIMATE VARIABILITY AND CHANGE IN THE

MID-ATLANTIC REGION

Some potential impacts from climate change cut across many of the region’s resources

or sectors. (For this discussion, sectors include fresh water, coastal areas, human health,

agriculture and forestry, industry and commerce, and related activities such as recreation.)

The major cross-cutting issues are economic growth and ecosystems. What we know

about vulnerability to potential cross-cutting impacts is described first, followed by a

discussion of vulnerability for specific sectors.

Economic growth, industry and commerce

Economic growth is broadly defined as the change in the region’s overall level of

economic activity (as measured by incomes, spending, or the number of jobs). Because it

occurs over time, economic growth is a dynamic process. Catalysts include population

growth, investment, increases in skilled and educated labor, technological innovations,

improvements in productivity, institutional innovations, and changes in government

policies.

Sometimes outside forces alter the basic structure of an economic system. The speed

of and expectations about these structural changes are important. Growth is most

dramatically affected by relatively quick and unexpected changes (e.g., a hurricane) because

it is difficult to adapt fully in a short period of time. In addition, immediate adaptation

may require that resources be reallocated away from productive, growth-enhancing uses.

On the other hand, slow and expected change (e.g., a rising sea level) allows for gradual

adaptation with only a slight impact on growth.

Adaptation not only mitigates damages (or exploits benefits) resulting from structural

changes, it often fuels the development of new innovations and also may provide firms

with incentives to look for more efficient ways to operate under current technology. In

turn, innovations and increased efficiency in production are likely to spur economic

growth. Thus, while climate change may adversely affect the status quo, society is capable

of adapting to take advantage of new opportunities as they arise.

Climate change will undoubtedly influence economic growth in the Mid-Atlantic

region. This workshop did not address regional effects of national and international

policies to reduce global greenhouse gas emissions. Instead, its focus was on how the

region might be affected if scientific projections of climate change are realized. However,

the potential economic impacts are largely uncertain. Because the Mid-Atlantic region is

not a closed system, it is difficult to predict future growth patterns. Prediction becomes

even more difficult when the uncertainties of climate change are considered. Any

economic impacts would be the result of changes in this region's climate as well as relative
40

to other regions. Adaptation may require a reallocation of production and trade practices

across regions and may influence people's migratory patterns, depending on changes in the

region's climate relative to other regions. In addition, policies in effect elsewhere may

influence adaptation and growth in the Mid-Atlantic region. For example, beach

protection and restoration projects in the Carolinas could induce emigration from MidAtlantic beaches to avoid the impacts of a sea level rise. In this case, tourism would

decline in the Mid-Atlantic, reducing growth for the region. Alternatively, economic

growth would increase if the Mid-Atlantic region became a relatively more desirable place

to live as a result of climate change.

Gross domestic product (GDP) in the Mid-Atlantic region has increased steadily over

the past several decades. Investment along with increases in a skilled and educated work

force are likely to be the most important economic growth forces in the region, as

evidenced by the fact that the finance, insurance, and real estate (FIR) sector, services,

government, and manufacturing are the largest current contributors to GDP in the MidAtlantic region (U.S. Department of Commerce). These forces could be influenced by

climate change. For example, an increase in natural hazards (such as an increased

frequency of hurricanes or flooding) would increase property damage and accidents and

thus increase the demand for insurance and payouts. The effects on the insurance industry

will depend on how well it can adapt to changing conditions. While rebuilding after a

natural hazard may spur economic growth in construction, this would require that

resources be reallocated from other uses, potentially slowing economic growth in other

sectors.

Other effects on industry and commerce from climate change and variability include

how snow, wind, rain, and fog affect the speed and safety of air, land, and water

transportation. Weather influences the operation of tourist facilities, mining and

construction sites, communications, power transmission, thermal power generation, and

water-dependent and other types of manufacturing processes. Roads, bridges, parking lots,

buildings, pipelines, power lines, sewers and other private and public infrastructure are

constructed for operation in seasonal climatic norms and with specific expectations about

the frequency and severity of extreme weather events.

Direct effects of climate change and variation on commerce and industry can be

positive and negative. For instance, increased winter temperatures may reduce damage to

highways from freeze-thaw cycles yet reduce economic activity dependent on cold

weather outdoor recreation. Increases in the frequency and severity of extreme weather

events that impair travel, manufacturing, construction, mining, and other activities will

adversely affect economic productivity. Infrastructure costs may also increase as

buildings, roads, bridges and other structures are constructed to withstand more extreme

weather.
41

Real estate markets could be negatively affected by a rise in sea level resulting from

climate change. Manufacturing dependent on water availability or having carbon

emissions could be negatively influenced by climate change if water becomes more scarce

or if government policy becomes more stringent with respect to carbon emissions.

However, manufacturing in the region may actually benefit if it becomes relatively more

costly to operate in other regions as a result of the same influences.

Industrial and commercial activities with forward or backward market linkages to

climate-sensitive sectors are also potentially vulnerable to climate change and variation,

particularly electricity and fossil fuel production. Increases in summer temperatures

increase the demand for electric power for cooling, while increased winter temperatures

reduce the demand for heating. Depending on the net effect, the demand for fossil fuels

and optimal power generation capacity may increase or decrease.

How climate change and variation will affect industry and commerce in the region

depends on the direction and pace of change, the vulnerability of these sectors in the

region, and the pace and impact of adaptation. Although these sectors are generally

considered to be less vulnerable and more readily adapted to climate change than natural

resource-based activities such as agriculture, fisheries, forestry, and natural ecosystems,

current understanding of vulnerability is extremely limited.

Agriculture, forestry, and fisheries are more likely to be directly affected because their

productivity directly depends on climate. Impacts to these sectors are more likely to affect

economic growth in rural areas where these industries are important (e.g., in southern

Maryland where watermen harvest oysters, crabs, and fish from the Chesapeake Bay).

However, the growth impacts for the region as a whole are likely to be small because

agriculture, forestry, and fisheries combined contribute less than 1% to the region's GDP

(U.S. Department of Commerce). In addition, producers and consumers will adapt (to

some extent) to any change that occurs. For example, agricultural adaptations may

include switching to crops better suited to the new climate, altering the growing season, or

changing pesticide usage. Input and output markets could be influenced as a result,

altering prices and possibly influencing growth. New policies could be implemented to

help mitigate damages. Ultimately, management practices, market responses, and policies

will determine economic impacts.

Ecosystems

Ecosystems in the Mid-Atlantic Region will continue to be affected by climate

variability as well as by the stressors accompanying economic development and changes in

land use and land cover. Climate change may exacerbate some of these trends. Changes in

average temperature and precipitation as well as increased frequency of extremes in climate

variability (unusually wet or dry periods, unusually hot or cold spells) may overwhelm the

resiliency of particular species of plants or animals. Their loss may be replaced by exotic
42

species, but the characteristics of the ecosystem will be different both during the transition

period and when the area approximates a new equilibrium.

For example, projected increases in global temperatures are expected to move the range

of forest types northward, so that the Mid-Atlantic Region could have fewer sugar maples,

and perhaps more of other species, such as southern pines. Such a change is expected to

affect the region’s bird populations, as migration corridors are disrupted when some tree

species die off faster than suitable replacements grow. Dieback of forest prior to

repopulation by species adapted to a new climatic regime could have other impacts on

wildlife, forestry, and terrestrial hydrological processes. Changes in fire regimes and pest

populations could similarly affect the natural and economic value of forests, causing

impacts in recreation, hunting, and fishing in woodland streams. Forest fragmentation

could be a major impediment to species migration and forest regeneration after dieback.

Because of their role in pollination, changes in insect and bird populations could decrease

agricultural productivity.

For freshwater streams and lakes, climate changes would affect runoff (and thus

erosion, sedimentation, and pollutant transport), the magnitude and frequency of high and

low flow events, stream acidity, and oxygen availability. Projected increases in intense

precipitation events will scour stream banks, decreasing the reproductive success of aquatic

insects (which serve as food for fish as well as birds and waterfowl) and of fish that lay eggs

near the edges of streams. This currently happens when there is an intense rain event

during the critical reproductive period, but the relative infrequency of stream scouring

gives the susceptible populations time to recover. More severe and frequent extremes

under climate change could cause some local extinctions, with repercussions for predators

of the lost species. Increases in intense precipitation also are likely to flush more

contaminants into streams, adversely affecting sensitive species.

Warmer winters could lead to more abundant insect pest populations. This may be

offset by larger populations of predators such as warblers and the eastern phoebe, which

might have an expanded range due to milder January temperatures.

For coastal ecosystems, climate variability and change could alter the frequency and

magnitude of storm surges, alter the volume of freshwater inflows, change temperature

and salinity, increase sea level and thus lose marsh habitat to flooding, and increase anoxia

(lack of dissolved oxygen) and eutrophication (excessive fertilization of aquatic

ecosystems). All of these could affect species composition and reproduction, affecting the

commercial harvest of aquatic resources as well as recreation and tourism.

Many of the same human and climatic effects as in the coastal and freshwater areas

would occur in wetlands and riparian zones. Many of these areas already are stressed by

drainage and restoration of wetlands.
43

In forested areas, climate change could affect fire frequencies, pest ecology, species

dominance, secondary wildlife effects, soil processes, and forest productivity.

Relic landscapes are an important feature of the Mid-Atlantic Region, contributing to

erosion and sedimentation, acid mine drainage, disruption of ground water, and

suppression of natural ecological succession. Climate changes affecting precipitation and

runoff could exacerbate these problems as well as change potentials for land restoration.

The workshop’s discussion group on this topic noted that ranking of ecosystem

impacts would be “very difficult” at best; subjective value judgments would make such a

ranking almost meaningless. For example, there are huge uncertainties associated with the

non-market valuation of the resources in the region. However, it is clear that some

ecosystems may have greater economic value to society than others; relict ecosystems

might have lower or even negative value.

Uncertainty associated with the available regional predictions of future climate change

make it difficult to specify, at this time, the greatest ecological vulnerabilities to climate

change. Based upon a dynamic forest model driven by output from five different global

circulation models (GCMs), one view was that the net impacts on forest would be

negative. All of these GCMs indicated a decrease in the availability of moisture during the

growing season. Recent Penn State downscaling research indicates that the region may

actually experience an increase in precipitation and a less dramatic increase in temperature

relative to the results from earlier GCMs. Furthermore, the omission of the climatic

effects of aerosols in the earlier GCMs also may have significant implications for the use of

these GCMs in ecosystem modeling. The discussion group agreed that there is significant

uncertainty in the predictions of future climate and that even the sign of climate change is

not clear at a regional level.

The group also perceived significant uncertainties in our knowledge of the current

state of the region’s ecosystems. It may be more possible to identify the types of regional

vulnerabilities that exist rather than the magnitude of those vulnerabilities.

Water resources and water quality

Recent climate variation has produced a moisture regime in the Mid-Atlantic that has

varied dramatically, as described in Chapter 1: Setting the Stage. The 1960s was perhaps

the driest decade in centuries, while the 1970s may have been the wettest. In the recent

years, the region not only suffered significant droughts (1986, 1988, 1991, and 1995), but

also experienced record snow packs (1996) and rainfall totals (1996), local flash floods

(1996), and region-wide billion-dollar floods (1996). Model projections of greater climate

variability and a more active hydrologic cycle mean that variations in water will be

fundamental parts of climate change. Recent hydrologic variation could be an early

expression of climate change.
44

Climate-induced variation in hydrology creates havoc for the region’s water users,

from agriculture to industry, and households to institutions. For example, little of the

Mid-Atlantic Region’s agriculture is irrigated, and drought frequently has significant

impacts on yields and income. Significant losses accrued during the short, intense drought

of 1995. Ironically, other years can be too wet for farmers in the region to carry out

normal, timely mechanical operations, and this excess precipitation can cause crop damage

associated with fungus and pests. The very next year after the drought, 1996, produced

these problems throughout the region. Furthermore, dry years reduce the dilution of

agricultural runoff, while exceedingly wet years and floods release more manure and

associated pathogens into the region's waters. Climate change could make the situation

worse. For instance, if the future brings more frequent droughts, then farmers will have

to consider investing capital in irrigation equipment. Such a switch to irrigation would

also require major investments in regional water supply infrastructure.

Regional water supply and demand and their management are also greatly affected by

climate variation and may be influenced even more by climate change. For example,

drought and water withdrawals could lead to saltwater intrusion in coastal aquifers.

Salinity intrusion would be exacerbated by sea level rise. Current water management

practices have been developed to adapt constantly to the present range of climate

variation, but during recent decades numerous cases of supply problems have been

evident. Still, water supplies would probably allow future users to meet their needs if

there were no changes in the economic, cultural, regulatory, or climatic environments.

However, it is likely that none of these environments will remain static, and that the

impacts of economic growth, lifestyle change, and safe drinking water regulations may be

as large or larger than the effects of climate change. Successful adaptation of water supply

systems to climate change must focus on increasing flexibility through demand

management and institutional adaptation. It is important to consider that many

technological adaptations to climate change, such as reservoir construction, require large

investments and long lead times.

Regional climate change predictions are still uncertain, but climatologists are confident

about the likelihood of some changes. Changes in average temperature and, especially,

precipitation totals are potentially large. Sea level will rise and more intense rainfall events

appear likely. Higher temperatures would increase water demand for irrigation, outdoor

domestic use, and cooling; higher water temperatures and altered lake levels and stream

flows would have ecological impacts. Coastal zones will be at risk of increased storm

losses, inundation, and salt-water intrusion of aquifers. The impacts on runoff, and

therefore the region’s renewable water supply, are uncertain, but could be great.

Nevertheless, workshop participants expected population, technology, economic

conditions, institutions, politics, lifestyle, and the values that society places on alternative

water uses are likely to have greater impact on the region’s water supply than climate
45

change. Social scientists presently cannot project accurately how these factors will

influence water supply and demand over the useful life spans of water projects or the time

scales of climate change.

In short, climate has a huge influence on regional hydrology, and water is fundamental

to most economic and all environmental systems. Therefore, climate variation and change

touch a broad range of water quantity and quality issues.

Agriculture, forestry and fisheries

Most of the land in the Mid-Atlantic region is devoted to the production of

agricultural products or is forested. The region includes some of the nation’s most

productive non-irrigated agricultural lands, and in the Amish of Pennsylvania, a unique

agrarian culture. It also includes some of the highest quality hardwood resources in the

world. Beyond the direct contributions of commercial agriculture and forestry to income

and employment, agricultural and forest lands shape the landscape and provide valuable

open space and rural amenities for this highly populated region. They are important

resources for outdoor recreation activities and tourism. These lands and the ways that

they are used also have significant impacts on water supply and quality, wildlife habitat,

and other resources throughout the region.

There has been less integrated climate change assessment research for forestry and

fisheries than for agriculture. Changes in climatic variables can directly affect growth and

production of crops, livestock, forests and fisheries. For plants and forests these variables

include temperature, solar radiation, soil moisture, and atmospheric CO2; for animals, the

direct effects of weather and extreme events; temperature and precipitation also influence

fisheries. For agriculture and forests, changes in climate-affected soil processes (e.g.,

nutrient leaching, salinization, erosion) and in weeds, insects, and diseases that are affected

by climate and atmospheric constituents could be important.

Biophysical responses of crops, livestock, forests, and fisheries to direct and indirect

effects of climate include both positive and negative effects. Increased CO2 concentrations

would increase the yields of most crops, corn being the only noteworthy exception, and

possibly increase the primary productivity of the temperate forests found in the MidAtlantic region. For annual crops, increased temperatures tend to speed development but

may reduce yields and increase the potential for moisture stress. Warmer temperatures

could increase agricultural productivity because of the longer growing season. Forestry

growth will increase particularly at the higher elevations because of the longer season,

provided there is no water stress. Primary productivity may increase with elevated CO2

concentrations and nitrogen mineralization rates, again except in drier regions. Increased

variability could also adversely affect productivity. For example, season reversal (fuzzy

seasons) may have a negative effect on perennial crops (fruit trees, forests) by interrupting

winter dormancy. Agriculture and forestry in low-lying areas, such as the Delmarva
46

peninsula, could suffer economic losses and resource degradation due to sea level rise.

Warmer temperatures could increase the range of pests for both crops and forests.

Increased temperatures may expand the suitable habitat for some commercial fish species

but reduce it for others. Extreme weather events can cause severe damage to crops and

livestock.

In general, freshwater fisheries in small rivers and lakes are highly vulnerable to large

changes in temperature and precipitation; freshwater fisheries in larger rivers and lakes are

less so. Globally, marine fisheries are least vulnerable and are not generally expected to be

significantly affected by climate change; the vulnerability of estuaries may be less than that

of freshwater fisheries but greater than that of marine fisheries. At the regional level,

though, estuaries like the Chesapeake could prove to be highly vulnerable to changes in

temperature, freshwater inflow, and salinity. The global generalization also may not

apply to anadromous species (i.e., species that spend time in both fresh and marine

waters), such as striped bass and American shad, which are economically important in the

region. In assessing impacts on fisheries and forests, note that economic importance and

adaptation options and costs are not necessarily correlated to biophysical vulnerability.

Recreation

Tourism and a wide range of outdoor recreation activities are important to the local

economies of the Delaware River Basin and Chesapeake Bay Region. Some of these

activities depend directly on temperature and precipitation, such as snow skiing. Others

have a less direct relationship. For example, warmer summers might encourage more

people to go to the beach. But increases in salinity and temperature in the Delaware and

Chesapeake Bays might cause more algal blooms so that the beach experience is less

pleasant. These conditions also could foster increases in cholera bacteria, leading to beach

closings and subsequent decreases in the patronage of motels, shops and restaurants that

cater to people vacationing at the beach. Sea level rise, exacerbated by an increasing

number of sediment-trapping dams, will contribute to beach erosion, imposing costs for

beach enhancement, erosion control, or from lost vacation revenues in resort locations.

The demand for many forms of outdoor recreation may decline if there is an increase

in the number of extremely hot, cold, or cloudy days; outdoor recreation simply is not as

much fun when weather conditions are less appealing.

Other recreation effects may derive from ecosystem impacts. For some people,

recreational fishing may be less enjoyable when the species mix changes. Current research

suggests that climate change will cause a decline in cold-water game fish in the MidAtlantic Region. However, research in Pennsylvania found that anglers tend to care more

about catching "something" than catching a target species. This suggests that sport fishing

in the Mid-Atlantic Region could become more attractive, because total fish populations

might increase (even though the species mix would be different than today). However,
47

cold-water fishing may be more economically valuable than cool- or warm-water fishing,

and thus be threatened more by warmer water conditions. Habitat changes will also affect

hunting; for migratory waterfowl, habitat changes along migratory routes outside the

region could affect hunting opportunities even if local habitat changes were to prove less

significant. Increasing winter temperatures could pose a threat to the viability of skiing,

either through shortened seasons or increased snow-making costs. Other winter sports

would be similarly affected: ice fishing, skating, snowmobiling.

Natural hazards/extreme events

Severe storms, floods, drought and heat waves are the principal natural hazards in the

Mid-Atlantic Region today; each may become worse with climate change. For example,

the enhanced climate variability of the 1990s has included more frequent, powerful, and

unusual winter storms and greater snow accumulations and impacts. The January Blizzard

of ‘96 dumped record snowfall throughout much of the Mid-Atlantic. It was followed a

week later by a storm with spring-like characteristics, including high rainfall totals and--

most important--the ability to melt the thick snowpack in a half day. The resulting flood

losses were approximately $1 billion. Two of the region’s three biggest floods this century

(March 1936 and January 1996) were associated with this scenario. If climate change

means more powerful winter storms, greater snowfall accumulations, and more rapid

snowmelt, then such floods and their impacts could become more commonplace.

The dozens of heavy thunderstorms during the summer of 1996 contributed to the

Mid-Atlantic Region’s record precipitation total for the year. For instance, State College,

PA received more than 5 inches of rain in 40 minutes on June 17, while Gettysburg, PA

had nearly a foot of rain in 10 hours on June 19. Exactly one month later, five western

Pennsylvania counties were declared federal disaster areas from a storm that contained 17

tornadoes and caused record flash flooding. More deadly thunderstorms and floods hit the

state in August. Localized flash floods from thunderstorms were ubiquitous throughout

the Mid-Atlantic and occurred almost daily that summer.

By definition, a natural phenomenon cannot be a hazard unless it intersects with the

human world.

Table 4 shows that the region’s managed ecosystems and socioeconomic (i.e., human)

systems currently under stress are further stressed by the region’s weather and climaterelated natural hazards. Several socioeconomic forces drive the interaction between these

hazards and society. Economic, population, technological, institutional, political,

behavioral, and cultural development and change work together to put people and their

managed systems in harm’s way. For instance, land-use decisions, such as building in one

of the region’s river valleys, result from the interaction of several socioeconomic drivers.

However, building in a floodplain puts the structure and its inhabitants at risk. If a flood
48

occurs, destroying a house and perhaps injuring the inhabitants, then the region’s health

and emergency services, social services, and insurance systems are stressed.

Table 4. Natural Hazards Impacts on Currently Stressed

Managed Ecosystems and Socioeconomic Systems

Managed Ecosystems &

Socioeconomic Systems Droughts Floods SevereWeather

Tropical

Storms

Heat

Waves

Cold-Air

Outbreaks

Pestilence/

Infestation

Fisheries 3 3 3 3 3 3

Water Resources 3 3 3 3 3 3 3

Agriculture 3 3 3 3 3 3 3

Transportation 3 3 3 3 3

Energy Distribution 3 3 3 3 3

Financial Services 3 3 3 3

Government &

Private Insurance 3 3 3 3 3 3

Social Services 3 3 3 3 3 3

Health Services &

Emergency Response 3 3 3 3 3 3

The Mid-Atlantic Region’s socioeconomic drivers will change as its economy develops,

and its population alters in both numbers and location. Social scientists cannot predict the

exact trajectory of future socioeconomic systems, but it is certain that these systems will

face challenges and stresses. One of these stresses will be weather- and climate-related

natural hazards.

Observations have shown that the frequency of severe thunderstorms with excessive

rainfall is becoming more common in the region; theory and modeling suggest that

climate change should bring more of these events.

Human health

Human health risks are governed by many factors, ranging from socioeconomic status,

to the availability of clean water and nutrition, to the quality of the health care

infrastructure. Over the last decade, climate and climate change have become recognized

as significant factors influencing health risk. Climate change and variability can affect

health directly, through extreme heat waves and cold episodes, and through severe

weather such as hurricanes and tornadoes. Climate change can also influence human

health indirectly, through (1) changes in the range and activity of vectors (disease-carrying

insects), intermediate hosts (such as animal reservoirs) and infective agents; (2) changes in
49

water- and food-borne infective agents; and (3) altered food (especially crop) productivity.

Examples of human health vulnerability in the Mid-Atlantic States illustrate the nature of

this issue.

Summer 1995 brought a strong early-summer heat wave to the Mid-Atlantic Region

and resulted in high mortality in Philadelphia, PA. Mid-latitude cities, already

characterized by large urban heat island effects, appear to be the most susceptible to heat

waves. The heat-related mortality that has occurred in cities such as Chicago, St. Louis,

Washington D.C., and New York City disproportionately affects the young, elderly, the

economically disadvantaged, and the ill. Because many of these deaths stemmed from

socioeconomic factors and were preventable, there is considerable hope for adaptations to

help check the impacts of heat waves.

Phenomena such as El Niño are associated with changes in rainfall, producing flooding

and droughts in different regions. Based on climate model predictions, climatologists have

speculated about whether anthropogenic warming will produce more intense or more

frequent hurricanes along the East coast of the U.S. Severe weather, of course, has wellknown potential to kill and injure.

Vector-borne diseases are a major cause of illness and death across the world. Disease

vectors and reservoirs (e.g., mosquitoes and rodents) are strongly influenced by climate.

For example, Dengue fever is transmitted by the bite of a mosquito (Aedes aegypti and

Aedes albopictus). Both mosquitoes are currently present in Florida and Texas (an

outbreak of Dengue occurred in south Texas in 1986). But U.S. cases are uncommon,

probably because of high standards of housing, and adequate water, sewer, and waste

management systems. The mosquitoes that transmit Dengue are strongly controlled by

winter temperatures. Warming, particularly in terms of minimum winter temperatures,

could substantially increase the range of this Dengue vector, including the Mid-Atlantic

States. Malaria, caused by the protozoan parasites of the genus Plasmodium and

transmitted by Anopheles mosquitoes, also would extend its range and activity under

conditions of global warming. One type of adaptation would be to use pesticides for

controlling vectors that expand their range. However, there may be public health risks

associated with using pesticides for vector control, similar to current concerns about

agricultural pest management.

Wet-dry cycles also influence human health risks because of their influence on

predator-prey relationships. Historically, moving into a wet period following a few years

of severe drought provides advantages to rodent populations which can reproduce faster

than their predators (e.g., owls). Population explosions of rodents eventually lead to

invasions into human habitats and human food stocks, increasing the risk of disease.

Lyme disease, caused by a bacterium, has a strong climatic association as well. Lyme

disease is transmitted by the bite of a tick (Ixodes scapularis) which feeds on the whitefooted mouse, the white-tailed deer, and other mammals. The number of Lyme disease
50

cases is strongly correlated with the size of the deer population, and in turn, the size of the

deer population is correlated with the severity of winter conditions in the northeastern

U.S.

Increases in water temperatures and salinity elevate the risk of cholera in the Delaware

and Chesapeake Bays, especially from recreational contact.

Increased precipitation, especially if it occurs in intense events, could flush

contaminants, including Cryptosporidium, into private wells and public water intakes.

This protozoan is difficult to control because of its resistance to the typical water

treatment technologies that rely on chlorine disinfection; filtering can be effective, but

tends to be expensive and difficult to maintain properly. Children are at higher risk of

infection, partly because of their relative inattention to proper hygiene. People with

compromised immune systems are particularly vulnerable because they have difficulty

clearing the protozoan from their systems; there is no cure for the (usually self-limiting)

illness, cryptosporidiosis. Secondary infection is not unusual for health and child caregivers or from exposure at public swimming pools. The effectiveness of boil-water

advisories in reducing infection from contaminated water depends on issuing them quickly

and on the public following them properly. The potential magnitude of impacts is

suggested by the 1994 Crypto contamination of public water supplies in Milwaukee, where

more than 50 percent of those exposed to contaminated water became ill– a total of

400,000 people.

The U.S. is less susceptible to malnutrition and food shortages compared to much of

the world because of the breadth of food production and our capability for technological

adaptations. Nonetheless, climate change and variability may result in the need to change

crops and planting practices and may also influence the activity or emergence of crop

diseases. Costs associated with these changes may have eventual nutritional impacts on the

poor.

Reducing health risks associated with climate change and variability will require (1)

surveillance efforts, (2) increased research on changes in range and activity of vectors

associated with climate change, (3) disease prevention programs, (4) education for medical

and public health communities, and (5) public outreach.

C. REDUCING VULNERABILITY

This chapter has described several potential vulnerabilities to climate change impacts in

the Mid-Atlantic Region– even though there is substantial uncertainty in our current

knowledge of how large the impacts might be. The chapter also suggests that the region

might be quite resilient to some of these impacts, either because they would affect a small

part of the region’s resources or activities, or because the region could adapt to the
51

impacts. The next chapter further explores strategies that could adopted in the near term

to increase the region’s resiliency.

REFERENCES CITED:

Atlantic States Marine Fisheries Commission, 1990. “Source Document for the

Supplement to the Striped Bass Fisheries Management Plan - Amendment #4," Fisheries

Management Report #16, ASMFC.

Azariadis, C., 1993. Intertemporal Macroeconomics, Blackwell Publishers, Cambridge, MA.

Bazzaz, F.A. et al., 1996. “Elevated CO2 and terrestrial vegetation: implications for and

beyond the global carbon budget,” in B. Walker and W. Steffen (editors), Global Change

and Terrestrial Ecosystems, Cambridge University Press, Cambridge, UK.

Crane, R.B., and B. Hewitson, 1998. “Doubled CO2 climate change scenarios for the

Susquehanna Basin: Precipitation,” International Journal of Climatology, 18, 65-67.

Heberling, M., A. Fisher, J. Shortle, J. Lazo, and D. Epp, 1996. “Estimating the economic

effects of global climate change on Pennsylvania recreational fishing in the Susquehanna

River Basin,” presented at Society for Risk Analysis, New Orleans, December 1996.

Intergovernmental Panel on Climate Change, 1996. Climate Change 1995 - Impacts,

Adaptations and Mitigation of Climate Change: Scientific and Technical Analysis. Cambridge

University Press, Cambridge, UK.

Mendelsohn, R., W.D. Nordhaus, and D. Shaw, 1994. “The Impact of Global Warming

on Agriculture,” American Economic Review , 84(4):753-771.

Root, T.L., and S.H. Schneider, 1993. “Can Large-Scale Climatic Models Be Linked with

Multiscale Ecological Studies?” Conserv. Biol., 7:256-70.

U.S. EPA, 1995. The State of the Chesapeake Bay, Washington, DC.

U.S. EPA, 1995. Ecological Impacts from Climate Change: An Economic Analysis of

Freshwater Recreational Fishing, Washington, DC.

U.S. Treasury Department, Bureau of Statistics, 1996. Statistical Abstract of the United

States, Washington, DC.
52

Watson, R.T., M.C. Zinyowera, and R.H Moss, (editors), 1996. Climate Change 1995,

Impacts, Adaptations and Mitigation of Climate Change. Cambridge University Press,

Cambridge, UK.

Yahner, R.H., 1995. Eastern Deciduous Forest, University Of Minnesota Press

Minneapolis.

Yarnal, B., D.L. Johnson, B.J. Frakes, G.I Bowles, and P. Pascale, 1997. “The flood of ‘96

and its socioeconomic impacts in the Susquehanna River Basin,” Journal of the American

Water Resources Association, 33:6, 1299-1312.

Yarnal, B., P. Pascale, B. Reifenstahl, G.I Bowles, and E. Smith, 1998. “Vulnerability of

the Susquehanna River Basin’s Water Supply to Climate,” presented at Annual Meeting of

the Association of American Geographers, Boston, March 1998.
53

CHAPTER 3: IMPROVING RESILIENCY AND

CAPTURING OPPORTUNITIES

A. INTRODUCTION

The previous chapter describes what we currently know about potential impacts in the

Mid-Atlantic Region from increased climate variability and climate change. But the

region’s actual vulnerability will depend largely on how its people and ecosystems react to

those impacts. Thus disadvantageous sensitivities can be moderated by adaptation

(negative feedback) while beneficial sensitivities can be enhanced by taking advantage of

the opportunities presented (positive feedback).

An important task, then, is to identify strategies that would be effective in moderating

undesirable impacts and amplifying desirable impacts. But identifying and implementing

strategies takes resources so the question becomes “Is it worth it?” Existing knowledge

and approaches can help answer this question in instances described in this chapter.

Research is needed for other facets, as described in Chapter 4.

In the Mid-Atlantic Region (and elsewhere), some actions make sense for reasons other

than climate change, and have additional benefits in terms of mitigation or adaptation.

Obviously, identifying these actions is a top priority, but considering only those strategies

that are desirable for other reasons could preclude considering strategies that might

ameliorate some important regional climate change impacts (or take advantage of new

opportunities). In either case, informed decision making depends on 1) assessing the risks,

2) identifying components of natural and human systems that are vulnerable to the risks,

3) determining how important impacts are to the vulnerable components, 4) estimating

the benefits and costs of strategies to offset--or for those that are beneficial, capture--the

impacts, and 5) determining the distribution of these impacts and costs across society,

space, and time.

Risk assessment

Identifying the types of impacts and their likely severity is difficult for some of the

possibilities described in Chapter 2. Consider assessing the human health risks from

Crypto, for example. We can use downscaling models to project regional increases in

precipitation. But there are many steps between that projection and an estimate of the

potential increase in illness resulting from it. These steps include estimating how many

water intakes would be inundated and how many defective well casings would be subject

to overland flows; the concentrations of Crypto in the water at the intake (or well casing);

the effectiveness of filtration or other Crypto removal techniques; how much the "finished
54

water" is diluted by mixing from other water sources; the promptness of a boil-water

advisory (BWA) if the water treatment system cannot remove Crypto effectively; how

many people potentially would be exposed to contaminated water; the number of

consumers who become aware of the BWA and follow it effectively; the dose of Crypto for

those who fail to follow the BWA; and the dose-response function to indicate what share

of that group is likely to experience symptoms. Similar event-trees can be described for

other types of impacts. Understanding of linkages often is poor, and data often are

sketchy for conducting such risk analyses.

Vulnerability

The particular system elements affected may differ greatly across the topics discussed

in Chapter 2. Continuing the Crypto example, wells and surface water intakes in lowlying areas tend to be more vulnerable to contamination, particularly in areas where

livestock is raised. Children may be more vulnerable because of their relatively poor

hygiene. People working with animals (that are likely to be Crypto carriers) and those

caring for people who are ill are more vulnerable because of higher exposure levels. The

elderly and those with compromised immune systems may be more vulnerable because

their bodies are more likely to react to a given exposure level.

Environmental valuation

Relatively little research has been conducted on the societal importance of ecosystem

changes, although rough approximations can be made for a few specific impacts. For

example, farmers commonly import bees to pollinate their crops, so an increase in this

expenditure could be estimated if pollinating bird and insect populations were expected to

decline. But for most ecosystem impacts, value estimates currently are not available.

Continuing the example of bees, the farmers’ increased costs (to import bees to pollinate

their crops) account for only some of the values lost to society when an ecosystem is

affected. An important component is the value people place on just knowing the

ecosystem is there (and undisturbed), regardless of whether they ever expect to visit or

otherwise “use” the ecosystem. This component often is called “existence value.”

Information on the value of ecological impacts is improving, partly because of the

potential transferability of research done for natural resource damage assessments (which

are conducted after oil spills for publicly owned recreational resources). It may be feasible

to use data or estimates from such studies for comparable privately owned facilities that

would be affected. Research specifically related to valuing the ecological impacts from

climate change in the Mid-Atlantic Region is underway at Penn State and Carnegie-Mellon

universities.
55

Benefit-cost analysis (BCA)

This approach examines all the benefits and all the costs of a proposed action or

strategy. Measurement issues often are important, as suggested immediately above. In

examining how much impacts are worth, we also need to consider offsetting changes. For

example, increased storminess could reduce the number of beach vacation days. We need

to recognize that the loss to the motel owners may be offset by an increase in revenues to

the supplier of some other type of recreation. There still are some societal losses when

people who would have preferred to vacation at the beach end up taking at it at an indoor

arcade. Issues also arise because many mitigation and adaptation strategies would impose

costs now to prevent adverse impacts far in the future. Conventional discounting, a

common practice in business and public policy decisions, would reduce distant future

benefits to very small amounts, thereby making it unlikely that decision-makers would

adopt mitigation and adaptation strategies on economic grounds alone.

Distributional effects

Smart resource management decisions also depend on understanding of the

distribution of risks, vulnerability, and benefits/costs across society, space, and time. A

commitment to social equity requires analysis of which groups in society (defined by age,

gender, ethnicity, or economic status, for example) benefit and which suffer losses as a

result of climate change, and defining ways in which impacts (positive and negative) can be

equitably shared. Both among and within regions, changes, impacts, and adaptations will

occur in different ways in different places, as a result of their different physical and human

geography. And the same changes, impacts and imperatives for adaptation will occur with

different urgency across society and through space and time. Understanding social,

spatial, and temporal distribution effects can help to set priorities for policy and for

sequencing public and private investment related to climate change.

B. IDENTIFYING NEAR-TERM ADAPTATION STRATEGIES

Economic growth, industry and commerce

Businesses continually adapt to changing conditions. Developing innovations to

exploit opportunities and finding more efficient ways to operate under current technology

both improve their bottom line and stimulate economic growth. Households also adapt

to improve their standard of living at affordable costs. An example would be the increased

use of home insulation to enhance comfort and reduce home heating and cooling bills.

Stressors and sources of vulnerability that affect the region’s economy and

environment include land use, infrastructure, growth, the aging of regional population,

income distribution, race relations, global competition, deregulation, education, and the
56

availability of capital. Society, the economy, and industry also are affected by direct

environmental factors such as water quality, water supply, and air quality. The

workshop’s discussion group for this topic perceived many of these factors to be more

important than climate change to the region’s economy and the decisions faced by

individual firms.

The insurance industry has an important role in adapting to climate change. Insurance

allows people to trade a large uncertain loss for a smaller certain loss (i.e., the premium).

The uncertainty associated with climate change impacts on property will increase

premiums, compared with risks for which the premium can be based on historical records.

The insurance industry adapts easily to gradual changes, but the potential for larger abrupt

changes is a cause for concern. Actions such as “storm hardening” of homes in coastal

areas would protect groups now as well as those potentially affected by climate change. It

also would moderate increases in insurance premiums in coastal areas.

Some working group member felt that business is unlikely to consider possible climate

change when making decisions, because current knowledge about impacts and related

uncertainties is inadequate. That judgment is consistent with Penn State research results.

A limited survey of water-dependent industry managers in the Susquehanna River Basin

finds that they are not planning for climate change because of the uncertainty about

climate change, issues of more immediate concern to plant operations and profitability,

and the long time scales of climate change relative to industry planning cycles (Maynard et

al., 1997). Typical equipment replacement cycles offer industry ample opportunity to

respond to change. This survey and Yarnal et al. (1998) found that vulnerability to both

climate change and variability in municipal water supply were declining through

adaptation to water quality protection regulations. The resulting resiliency would help

industry and commerce as well as residential water users.

Because of the dominance of other sources of change, strategies to improve the general

economic resilience of the region will go a long way toward minimizing adverse economic

impacts and maximizing the advantage from opportunities caused by climate change.

Stressing that flexibility is crucial, the discussion group suggested several strategies that

could help both the regional economy and individual business managers:

1) Upgrading infrastructure to make it more adaptable

2) Paying more attention to land use policy, including metropolitan planning and

transport planning

3) Streamlining government operations

4) Retraining displaced workers

5) Sharing technology
57

The working group preferred incentives-based regulation and tax incentives for

shaping policy compared to prescriptive measures. Continual reevaluation of policy, in

response to technological innovations and to policy successes or failures, is another way to

increase flexibility. Some felt that policy should be formed at the national level, due to the

interdependence of regions within the United States, while encouraging regional flexibility

in implementation. The working group agreed that clear, visionary goals must be

established and communicated to all interested parties.

Some participants believed marginal changes to existing strategies and institutions may

be the best regional adaptation strategies for industry and commerce, partly because they

perceived existing industrial and public infrastructure as too inflexible to respond to

climate change. During drought conditions, for example “competitive use policies”

restrict water use by some industries in the Chesapeake Bay watershed. This can create

near-term difficulties, but responses can be directed at new infrastructure through the

normal capital replacement cycle. Excluding existing operations from more stringent

regulations or policy would slow adaptation to climate change, but reduce businesses’

compliance costs. Strategies could be intensified if climate change effects become more

apparent. This sub-group viewed radical change as unnecessary at this time. Others

disagreed with the assessment that infrastructure is too inflexible, but considered marginal

change strategies to be useful given the uncertainties involved. Still others were skeptical

that marginal strategies would prove sufficient for adaptation and mitigation, believing

that greater changes will become necessary.

In summary, industry relies on natural resources and infrastructure, which vary in

their vulnerability to climate change (e.g., through water shortages or increased likelihood

of blizzards). The discussion group expressed strong support for planning and structural

changes that affect future growth patterns, such as land use policy, which could be

accomplished at moderate cost. Because they considered industry to be capable of

adapting to climate change, some participants advocated a cautious approach including

more localized research that will be useful to firms and local authorities. The group

supported modest changes to existing strategies and institutions as appropriate immediate

means of adapting to climate change. Many participants believed that technology can be

relied upon as a significant source of long term adaptation options. The need for more

significant restructuring of existing infrastructure and industry, however, divided group

opinion.

Ecosystems

Although ecosystems sometimes have surprising resiliency, simultaneously they

sometimes are surprisingly vulnerable. This section suggests ways that human actions

might buffer ecosystems, giving them more chance to adapt to both current stresses and

those induced by climate change.
58

In the coastal region, strategies to help ecosystems adapt could include new zoning

laws on setback and elevation of structures and wetland restoration. Shoreline hardening

could preserve beaches and waterfront for human use, but might be a barrier for migration

of ecosystems. Here as in freshwater systems, genetic engineering, hatcheries, and

aquaculture could be developed, but attention should be given to their potential to push

“natural” ecosystems toward local extinction. For freshwater streams and lakes,

adaptation strategies could include fish management as well as modification of water

management strategies and structures. Protection of riparian zones as well as wetland

restoration could be important adaptation strategies.

Protection (or establishment) of forest corridors, propagation of seedlings, and changes

in forest and wildlife management could help forest ecosystems become more resilient.

Urban regions are already strongly changed by human forcing. Climate impacts will

include changes in water quantity and quality, pesticide and toxic chemical loading from

urban land, and transportation of toxic wastes. These changes could have effects on urban

forests and other ecosystems similar to those in natural forests and ecosystems.

Fresh water quantity and quality

Several regional adaptation and management strategies are recommended for adjusting

to or counteracting the impacts on freshwater from climate variability and climate change.

Flexibility is a key. Institutions and management practices that facilitate adaptation will

best be able to handle changes in water supply and demand. Examples include integrated

basin and watershed management of water facilities, conjunctive management of surface

water and groundwater, and inclusion of conservation incentives, water quality

protection, habitat protection (wetlands, riparian corridors), and supply reallocation

options in water management.

Government agencies play an important role in gathering information, including the

important task of monitoring the nation’s water supply. At the same time, government

agencies should provide industries and consumers with incentives to change use patterns

and develop technologies that mitigate human impacts on the climate and facilitate

adaptation to climate change. Institutional conflicts, such as the inability to enforce legal

regulatory powers, also require more attention.

Industries will respond by self-regulation and take a longer-term perspective

concerning these issues if financial incentives exist. It is important that industry take part

in land use planning and management, including the use of economic incentives, to

moderate the costs of climate change impacts. For example, most of the Mid-Atlantic

Region has been able to withstand recent droughts– although certain areas have fared

poorly during these events– but the region is not prepared for a very severe drought at
59

current usage levels. Standardized data collection would improve the development of

alternatives and management decisions.

Both education and the use of economic incentives are useful to develop effective

strategies. Interdisciplinary, multimedia education strategies are needed at the local level,

for officials and managers and for the public. All parties– government, industry, nonprofit and nongovernment organizations, and the media– have important education roles.

Finally, “win-win” strategies and actions that are cost-effective even without climate

change are much more likely to succeed. Projects initiated because of other concerns

could add “enhancing resiliency to climate change” to their list of benefits, often at modest

or no additional cost. Feedback to help evaluate the effectiveness of policies and activities

is also important for handling future climate change.

Agriculture, forestry and fisheries

Economic and policy adaptations to direct and indirect impacts of climate change will

affect the profitability of farm, forest, and fishing enterprises. Climate impacts will induce

behavioral adaptations by producers, input suppliers, processors, and consumers (e.g.,

changes in crops and production practices by farmers, changes in agricultural trade flows

between regions, changes in consumer food purchasing patterns) and stimulate demand for

techniques better suited to new climatic and economic conditions. Changes in production

will lead to changes in the prices of agricultural and forest commodities. Agricultural,

forest, and fisheries adaptations may happen faster if agricultural research and extension

can enhance technological response capabilities and disseminate research findings.

However, policies such as product price supports, input subsidies, agricultural trade

barriers, and payments for crop failures could hinder adaptation by encouraging the

production of climate-sensitive crops, the use of cropping systems ill-suited to the changed

climate, or limiting incentives for relocation or innovation.

Assessments need to distinguish between economic impacts and changes in physical

variables. Economic impacts depend on price changes and substitution possibilities, as

well as on changes in the underlying productivity of the biophysical systems. Prices are

determined by national and international forces and may move in ways that blunt or

amplify the biophysical change. For example, yield reductions do not imply an economic

loss to farmers, foresters, or fishermen if the prices they receive for their products increase

sufficiently. Similarly, because agriculture and forestry in different regions are linked

physically by the movement and management of weeds, pests, and diseases, and

economically by prices, policies, and commodity flows, regional impact assessments

require understanding of climate change, direct and indirect impacts, and adaptations in

other regions.
60

Several studies have explored the impacts of climate change on agriculture, mainly on

large spatial scales. Results vary according to factors such as the climate scenarios

considered, the modeling techniques used, and the extent to which economic and

technological adaptations are considered. These studies generally indicate that global

economic impacts of projected climate change on agriculture will be small. Projected

climate change is expected to have little impact on the overall U.S. economy and domestic

food production. However, impacts of climate change on agriculture at the regional level

are highly speculative. Both positive and negative impacts have been predicted for

agriculture in the Mid-Atlantic States, with the results differing according to the

methodology.

It is clear that adaptation can greatly reduce the negative impacts of climate change on

agriculture. For example, farmers can shift to less climate-sensitive crop cultivars, or to

less climate-sensitive crop and livestock production systems. The workshop discussion

group for this topic expected that well-informed commercial farmers and foresters would

adapt to climate change and variation through shifts in species, crops, livestock, and

management practices. Foresters can assist migration of forests through, for example, tree

planting strategies. Foresters have identified species that display broader tolerance to

environmental conditions. Fast growing species may be better adapted to continual

change, and foresters could rely less on natural regrowth of forests and more on planting,

perhaps using hybrid species. These adaptive responses would be driven by the direct

impacts of climate change on agricultural and forest enterprises, and by changes in

agricultural and forest product prices induced by climate change impacts in other regions.

This region’s agricultural economy could be more affected by changes in prices for

commodities, induced by changes in other U.S. regions and the world, than by direct

impacts on agricultural productivity from changes in the region’s climate.

Public education and technology transfer programs that provide farmers, foresters and

fishermen with information on future weather and technical options would facilitate

adaptation. The Cooperative Extension Service is an example of a system that could be

used to deliver this kind of information. In addition to public information systems,

increased development of private sector information services (weather forecasting) can

facilitate adaptation.

Improved monitoring and early warning systems could help avoid losses from extreme

events. Improved monitoring of current weather would help farmers avert losses

associated with frost, particularly in the fruit industry, and increase the effectiveness of

pest management strategies, particularly integrated pest management (IPM). Long-term

monitoring of forest inputs (e.g., nitrogen, acid precipitation, air quality) linked to forest

productivity and health are needed to understand how forests are changing and how these

changes are affected by changes in environmental conditions.
61

Income and employment in agriculture, forestry and commercial fisheries in the MidAtlantic region are small, so large impacts on the regional economy are unlikely. On the

other hand, local impacts, such as in the relatively small portion of the region where

commercial fishing occurs, could be substantial. The discussion group for this topic had

relatively little expertise for fisheries, so felt less certain about potential impacts and

adaptation strategies for commercial fishing.

Overall, the group concluded that predicted climate change does not represent a

significant threat to the region’s agriculture or forests in the next 50 years. Competition

for land, environmental regulation, and competitiveness will remain the key stresses in

agriculture. Similarly, other external stresses, such as land-use change and the chemical

environment (ozone, nitrogen deposition, acid precipitation) will be continue to be more

important than climate change in the forest sector. Agriculture appears to be more

resilient than forests, in part because of its shorter production periods, greater commercial

character, and value of output. Many forest values are unmarketed and the use of money

to protect value and take adaptive actions has not been a priority. Public sector responses

to protect nonmarket values are much more critical for forests than for agriculture.

Recreation

Many types of recreation adaptation can be envisaged. For example, increased risk of

contamination at freshwater or marine beaches can be offset by more use of swimming

pools. Warmer average evening temperatures may tempt more night-time outdoor

exercise, especially if daytime temperatures are uncomfortably warm. Similarly, an

increase in hot weather might lead to more requests for golf tee times very early in the

morning or the installation of more water fountains. Golf course owners may need to

irrigate more, an illustration that some forms of outdoor recreation may become more

costly.

Many of the potential recreation impacts--and thus adaptation strategies--are tied to

other topics discussed during the workshop. One example would be bird watching.

Ecological changes that modify the distribution of birds would affect people’s ability to

observe particular bird species. Thus management actions to protect bird migration

corridors also would help preserve this recreational opportunity.

Some types of adaptation initially seem obvious. For example, if the projected decline

in cold water recreational fish is more than offset by increased populations of warm water

species, trout anglers could switch to fishing for (say) largemouth bass. But the

recreational experience may be sufficiently different that former trout anglers suffer a

decline in well-being even when they catch more fish. It is an empirical question whether

adaptation (e.g., a large increase in bass fishing days) more than offsets the decline in wellbeing associated with a decrease in the earlier preferred recreational activity (e.g., a smaller

number of trout fishing days).
62

Natural hazards/extreme events

The types of adaptation that would reduce vulnerability to increased frequency or

severity of extreme weather events are the same as those frequently proposed for reducing

vulnerability to current patterns in extreme events. Among others, these strategies

include:

• Bringing more communities (and their residents) into the Federal Flood Insurance

Program, and enforcing its requirements.

• Planning more sensibly to restrict development in flood-prone areas.

• Reducing subsidies that encourage development and rebuilding in areas likely to

have flooding or severe winds.

Some of this adaptation may require more reliance on the insurance industry for

private insurance to reduce individuals’ and businesses’ financial risk from extreme events.

Possible avenues for adaptation include incorporating more knowledge about actual risks

when setting premiums, expanding available funds through further pooling and

accumulation of funds (which may require significant changes in practices and institutional

cooperation), as well as proactive efforts to reduce the likelihood of damage from extreme

weather.

Human health

Current information is sufficient for suggesting specific near-term strategies that would

have positive net benefits now because of climate variability and in the future when faced

with climate change. Judicious use of analogs based on past events can suggest

management strategies. For example, early warning and buddy systems can be combined

with the provision of cooled shelters to reduce heat mortality. Improved filtration,

detection, and effective boil-water campaigns can reduce exposure to vector borne disease.

People can be encouraged to move away from the risk of injury, drowning and

contaminated water in flood plains by removing flood insurance subsidies and limiting

government flood recovery assistance in locations prone to frequent flooding. The

appropriate extent of these near-term strategies can be determined (on a sub-regional basis)

by examining both their benefits (e.g., reduced health and property damages) and costs

(e.g., for heat wave warning systems, restricting land uses, protecting and improving water

supplies). Strategies such as removing subsidies for inappropriate behavior are relatively

low-cost. Low-cost options such as removing federally subsidized flood insurance can be

difficult to implement at a regional level without national action. Others are easier to

implement at regional and sub-regional scales.
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The following table proposes a variety of adaptations and management strategies to aid

in adjusting to and counteracting negative health impacts of climate variability and change:

Table 5. Improving Regional Infrastructure for Climate-Related Health Impacts

Heat Related Illness Pollution Related Illness Vector-Borne Diseases Extreme Weather Events

Identify areas at risk

Develop early warning

systems

Education/outreach to

public health

officials/systems

Improve building practices

(e.g. paint roofs, install roof

sprinklers)

Education

Monitoring and

surveillance

Monitoring and

surveillance (e.g. making

more diseases reportable so

that they can be tracked)

Vector control (e.g.

integrated pest

management)

Environmental

modification

(e.g., removing old tires)

Disease ecology

(upstream information)

Remove populations in

high risk areas (e.g. remove

incentives for living in

flood plains)

Strengthen water supplies

against contamination

(public and private)

Educate water managers

Monitoring for climate-related disease is important, but there is debate about the best

way to do so. Looking for indicators (e.g., precursors or vectors) of the potential presence

of the disease may lead to prevention strategies, but such monitoring and prevention can

be both costly and uncertain. In instances where the number of cases is likely to be small,

it may be cost effective to focus on treating people who become ill, rather than

monitoring precursors.

Illness related to climate change provides more opportunity for preventive measures

because its nature is environmental exposure, compared with illnesses with larger genetic

or behavioral components. At this time we cannot resolve the preventive versus

treatment issue; the more cost-effective method may vary by disease and depends upon

disease ecology and the degree of exposure to disease pathogens. A priority should be

promoting interdisciplinary work and collecting data.

Education and communication with stakeholders are essential. Stakeholders include

groups that could be affected by, or who have the potential to influence, health impacts

from climate change. These stakeholders must be identified, along with their information

needs and the most effective information delivery system(s). For instance, the medical

community must be educated in environmental health and be made aware of what diseases

might occur. Effective strategies are unlikely to be implemented unless government (federal,

state, local) and funding officials understand the potential size of regional health impacts of

climate change. Thus these officials are another example of stakeholders. The largest
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stakeholder groups, of course, are among the general public. Educational/informational

programs can help them make informed decisions about adapting to health threats from

climate change.
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CHAPTER 4: RESEARCH NEEDS

A. INTRODUCTION

The previous chapter suggested near-term strategies to address problems already

recognized or that represent a “win-win” approach to climate impacts in the Mid-Atlantic

Region. Closer examination of their potential effectiveness and costs can be expected to

reveal gaps in our knowledge that can be filled by information gathering and research.

Even more compelling reasons for research are the substantial uncertainties about just

how the region’s climate is likely to change over the next century, how this will affect

both managed and unmanaged ecosystems, and how individuals and communities will

respond and adapt to these changes. This chapter brings together suggestions about

research judged to be most useful for helping the region’s citizens make wise decisions

related to the impacts from climate change.

B. DIVERSE RESEARCH NEEDS

Economic growth, industry and commerce

Workshop participants perceived climate impacts to be a limited threat to the MidAtlantic region’s wide range of industry although there might be substantial impacts on

other economic activity. They were not confident in these perceptions, because of the

lack of information on the local climatic impacts that business may face, as well as how

likely such climate change risks are relative to other risks facing the economy.

Whether risks are short or long term is important for business planning, especially for

long term capital investment, plant location, and raw material availability. Thus, studies

of possible climate change impacts should involve risk comparisons, including the time

horizon of these risks. Because of its vulnerability to climate change, the insurance

industry is particularly interested in risk research.

Options developed in the past to minimize business risk, such as flexible input sources,

support the perception that industry generally can adapt. Because such observed

adaptability makes many future scenarios seem less threatening, extreme case scenarios can

be a useful planning tool. The chances of such events are remote, but their disastrous

consequences would be beyond the means of adaptation and amelioration by current

institutional frameworks. Research that identifies institutional vulnerabilities and

remedies would be valuable to society in general, as well as to industry in particular.
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Assessing the importance of climate variability and climate change on industry and

commerce requires information on a much finer scale than currently available, a scale that

can be used by water managers and individual firm-level decision-makers. Thus workshop

participants perceived research at the localized level to be much more beneficial than

continued research on global scale general circulation models (GCMs). Such research is

likely to be most effective if focused on sensitive sectors and areas within the region.

Historical data, including data collected by industry, may be useful in this regard. The

dissemination of information from climate change studies, such as the IPCC reports, also

can aid industry decisions. The business community’s expectations about climate change

and variation are important because current investment decisions influence the region’s

future vulnerability.

Research is needed to determine how increased frequency of extreme weather events

and changes in water supplies (e.g., because of their use in production processes and for

diluting chemically and thermally contaminated effluents) could affect the region’s

economic productivity and competitiveness. We also need research on the effectiveness of

existing and new technological, economic, and public policy adaptations that could

ameliorate adverse impacts.

Recreation is expected to be an increasingly important economic activity in this region

and elsewhere. Substantial research is available on recreation in the Mid-Atlantic Region,

but it may not cover all forms of recreation potentially affected by climate change.

Relatively little of this research has been tied to factors that might be influenced by

climate change. An assessment of which types of recreation are likely to be most affected

and the importance of these activities to the region could suggest near-term adaptation

strategies as well as further recreation research priorities.

Ecosystems

Workshop participants agreed that climate variability and change could have profound

effects on natural and human-modified terrestrial and aquatic ecosystems, in conjunction

with other driving forces of ecological change. Yet the specifics of those profound effects

are unclear. As a first step, we need to synthesize existing information to determine which

species in the Mid-Atlantic Region are especially vulnerable to exacerbated climate

variability and likely trends in average precipitation and temperature. Along with a

preliminary assessment of the ecological roles of vulnerable species, this synthesis will

allow identification of gaps in available data and suggest priorities for a research agenda.

Differing time scales of climate change as well as the intrinsic nature of these changes

directly and indirectly affect ecosystems, ranging in time from short-term stochastic events

to major long-term eras such as the Pleistocene glaciation. We need to understand more

about the directions and rates of climate change anticipated in the region before we can
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understand how ecosystems might respond to these changes in comparison to their

responses to the spectrum of other events that will occur.

An example might be coastal engineering strategies, such as integrated coastal sediment

management. Research could examine the ecological effects (and effectiveness) of

enhancing sediment to increase the rate of vertical growth and avoid consequences from

sea level rise.

As mentioned earlier, climate-induced changes could have significant economic impact,

as well as affecting inherent ecosystem values. Evaluating future ecosystem impacts

requires: (1) determination of the direction and magnitude of climate change (as well as the

speed of its onset) in the region; (2) improvements in the duration and spatial/temporal

resolution of ecological monitoring; and (3) improved theoretical models of ecosystem

functioning. Greater understanding of the present extent, density, composition and

dynamics of ecosystems in the region is needed for assessing the impacts of human,

natural, and climate driving forces.

Water resources: quantity and quality

Because most of the stresses on the Mid-Atlantic Region's water resources are directly

or indirectly associated with population and economic growth, additional research that

aids in projecting the region’s economic growth and population would be especially

helpful.

To assess how great the stresses on water resources from climate variability and climate

change will be, better information is particularly needed for: accurate regional climate

modeling; understanding how climate and water resources interact; how climate affects

unmanaged ecosystems; how climate change will influence natural and agricultural

vegetation and runoff; how ecosystem changes will affect water quality and quantity; and

how to reduce scaling mismatches between climate model output and input information

necessary for water management and planning.

Choosing wise adaptation and management strategies requires good information on

how climate change could affect water supply, both on average and in terms of variability.

Water demand information is important because climate change could affect both instream

and withdrawal uses. Information also is needed on the effectiveness and costs of

alternative demand management and water supply strategies.

Other information needs include projections of land cover change, the frequency,

magnitude and distribution of extreme events, evapotranspiration rates, and how climate

change will affect potential demand for water use in agriculture. Some of this information

is particularly important to water management because of the reliance of water managers

on historical data in planning future infrastructure. For example, the region currently has
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very little reliance on irrigation, which could be an inappropriate signal for future

irrigation demands.

Communication between researchers and politicians, in particular, must be

strengthened so that researchers develop tools that are useful to managers.

Agriculture, forestry and fisheries

The major stresses for the Mid-Atlantic region’s agriculture are economic factors (e.g.,

competitiveness, taxes), regulatory issues (e.g., labor, environment), and land-use pressures

(land competition). These are more important determinants of the viability and vitality of

agriculture in the region than climate variations per se. For forestry, climate variability

may interact strongly with other environmental stresses (insect pests, ozone, nitrogen

deposition, acid precipitation) on forests. The working group lacked detailed information

on how humans use and enjoy forests, and the forest economy, thus making it difficult to

understand how climate change and variation will affect forest values, particularly those

non-timber values, such as recreation, scenic views, wildlife habitat.

As is the case for other sectors, predictive scenarios are the largest unmet information

need to facilitate adaptation in agriculture and forestry. For example, will the region’s

climate be wetter or more variable, and how much wetter or more variable? Short-term

climate scenarios (the next few decades), including realistic transient representations of

climate change, are particularly important. More research also is needed on forecasting

medium run (6-18 months) climatic conditions with a focus on extreme weather events

and on understanding how to prepare for these events.

Agricultural and forestry research can help farmers and forest managers adapt. For

example, developing new crop cultivars could make agriculture less climate sensitive.

Maintaining the genetic base for the development of crops is crucial, especially for the socalled “minor crops” that are important for this region. Similarly, forestry research can

help forestry managers adapt, although forests’ slower growth rates mean it will take

longer than in agriculture.

Although fisheries were not well represented by the experience and expertise at the

workshop, it is clear that recreational fishing is economically more important than

commercial fishing in the region. This is due to the large and growing public participation

in this activity and the economic impacts of recreational spending. Research needs for

recreational fishing include learning more about the relative values anglers place on

different types of fishing opportunities, as well as refining projections of how climate

change would affect different recreational fishing opportunities.

Integrated regional-scale research on how climate change and variability will affect

agriculture, forests, and fisheries is essential to understand impacts on people and
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communities economically dependent on these sectors. However, beyond their

contributions to income and employment, each of these sectors is a source of important

nonmarket services (e.g., open space amenities, wildlife habitat, ecosystem services,

cultural values) that could be increased or diminished. Further research on regional

climate change and variability, direct and indirect impacts on biophysical productivity,

and technological and economic adaptation options and costs in Mid-Atlantic Region

agriculture, forests, and fisheries is essential to understanding potential consequences for

land use, land cover, water supply and quality, and other issues of societal concern.

Natural hazards

Climate change may alter the frequency and intensity of natural hazards, thereby

changing this stress on natural and managed ecosystems and on socioeconomic systems.

It would be ideal to know how climate change will affect the natural hazards profile of

the Mid-Atlantic Region. Regionally specific climate predictions on all time scales would

help planning efforts to prevent or moderate damage from floods, droughts, heat waves,

cold-air outbreaks, and other climate-related disasters. Such information would save lives

and reduce economic losses. However, precise regional predictions of weather and climate

may never be possible, and it is unlikely that accurate socioeconomic forecasts will ever

exist. Nevertheless, there are many research and information needs that, if satisfied, could

reduce current and future vulnerability to weather- and climate-related natural hazards.

Workshop participants identified four basic research and information needs for

weather- and climate-related hazards:

• More must be known about the links between individual hazards and the

vulnerabilities of the region, including overall vulnerability and vulnerability by

socioeconomic sector. Gaining this knowledge requires research on climate

impacts, hazards, and socioeconomic drivers.

• Relationships between individual events and variation in the climate system on all

time scales must be clarified. For example, does a wetter summer climate over the

Mid-Atlantic Region translate into more locally severe storms and flash floods?

Does increased (decreased) climate variation mean increased (decreased) natural

hazards?

• Climate and natural hazards data must be collected at finer spatial and temporal

scales. A match between the space and time scales of natural and socioeconomic

data must be developed and incorporated into monitoring networks.

• The needs and concerns of interested parties must be incorporated in weather and

climate research relating to disaster mitigation.
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Although it will take time to develop the first three of these items, action should be

taken now to build user requirements into climate-related hazards research.

Human health

Choosing long-run regional health strategies in the face of climate change will require

improved general climate information such as the nature of projected climate variability in

the Mid-Atlantic Region and the impact of the North Atlantic Oscillation (e.g., the

distribution of rainfall and temperatures, including freezes that reduce disease vectors,

etc.). Thus reference radio sondes (the weather balloon instruments that broadcast their

measurements of temperature, humidity, air pressure, etc.) should be supported.

More must be learned about how climate change would affect genetic mutations and

diseases resistance, as well as how ecosystem changes would affect disease vectors.

Research on changes in the dynamics of transmission, distribution and resistance of disease

agents (ranging from environmental factors such as temperature, humidity, and rainfall

that affect survival of the disease organism, to vectors such as insects that carry the disease

to people, to the human host that actually experiences the disease) can help in projecting

the potential for the emergence of diseases new to the region. For example, warmer

temperatures could increase algal blooms in the Chesapeake Bay, which might harbor

cholera. At the same time, other diseases may move out of the region. Increased rainfall

and flooding could contaminate public and private water supplies (e.g., with

Cryptosporidium), accompanying the property damages often thought of as the primary

impacts from weather hazards. More climate variability also could lead to poor water

quality during drought conditions, accompanied by health impacts for people with limited

access to clean water.

A key issue in determining the health effects of climate change is understanding what

will happen to the threshold level of tolerance of the population and of the region’s disease

agents. The threshold could stay the same if adaptation to climate change occurs. But the

threshold could move, for example, if higher humidity levels cause people to be less

resistant to disease-carrying insects. Climate variability may be a more important

influence on health than climate change. Negative impacts of climate change would

increase health care costs and stress on health care facilities.

Furthermore, knowledge of sociological response to physical stress is important (i.e.,

will people move or adapt; and if they do adapt, what is the adaptation process?) in

addition to understanding how the risk and cost of climate change will be spread across

the region’s population. Mental health may be affected by increased precipitation (grey

weather) and by dislocation of people due to extreme weather events. Thus

interdisciplinary research teams that can account for the physical, biological and social

interactions will be essential for projecting regional health implications. Similarly,

multidisciplinary prevention planning teams can avoid trading one problem for another.
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C. MOVING TOWARD A RESEARCH AGENDA

The list of research needs described in the sections above can seem overwhelming.

However, research needed from one perspective or sector to enhance wise decision-making

about climate change often also is needed for another sector or perspective. In addition,

data or understanding from much of the suggested research would improve the region’s

ability to make smart decisions even in the absence of climate change. Recognizing these

linkages may make it easier to a) get support for research that will have benefits for

planning the region’s future in general and b) setting priorities among the research topics

more targeted to projecting and ameliorating negative impacts from climate change.

The research agenda outlined in Table 6 summarizes the research needs identified

above. The table identifies research that would provide answers broadly applicable to the

Mid-Atlantic Region’s overall vulnerability to climate change, as well as research needed

for the major sectors likely to be affected by climate change.

The final chapter in this report summarizes the findings of the workshop and

recommendations for the next steps.

Table 6. Research Agenda

Basic research important for many sectors:

Climate research

• Regional models and scenarios

• Extreme events

• At scale useful for public and private decision-makers

Biochemical/Ecosystem research

• How nutrient cycles, plant growth, and competitive advantages for individual species within

communities will be affected by increased CO2, temperature, sea level rise, induced soil salinity, and

flooding from extreme weather events

• Changes in animal populations, based on changing plant food supply, particularly for

• hunted species

• disease vectors

• charismatic bird species

• agricultural pests

• Improved techniques for ecological monitoring and collaborative ecosystem management

Socioeconomic research

• Improved predictions of human migrations and demographic changes
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• Links between human demography and climate variables

• Attitudes toward and values for environmental and ecological characteristics

• Differences in risk between private and public sector activities

• Issues of environmental justice; where are impacts greatest?

• The role of information in initiating responses to minimize risks or maximize opportunities

• How institutional and technological change can diminish risks and enhance opportunities

Sector-specific research (given answers to basic research questions):

Forestry

• Clarify most vulnerable aspects of forest business

• Separate climate impacts and other human impacts along urban/rural gradients

• Link human demography with forest history and climate predictions to understand potential forest

species migration

Agriculture

• Improve prediction of soil moisture, and its timing

• Clarify most vulnerable aspects of agriculture related to potential changes in plant growth

• Link human demography with agricultural history and climate predictions to understand potential

for farmer willingness to adapt to climate change

• Identify best potential species under climate change

Water

• Given results of human demography studies, project location and extent of stress on water,

including effects of land use/land cover

• urban/rural gradients

• coastal/inland gradients

• Improve predictions of climate change impacts surface and ground water availability and impacts on

its quality

Health

• Link human demography, disease vector migration, water quality, and climate predictions to

understand potential health changes, overall and in sub-regions

• Potential impacts on mental health and disease resistance

Recreation

• Clarify climate-sensitive aspects of recreation, especially as related to plant and animal populations

• Given human demographic and valuation research, prioritize conservation efforts
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CHAPTER 5: SYNTHESIS, CONCLUSIONS AND NEXT STEPS

A. INTRODUCTION

Four questions guide the organization of this chapter:

1. What do we know about the impacts of climate change in the Mid-Atlantic

Region?

2. What strategies can be considered now for reducing vulnerability and taking

advantage of opportunities presented by climate change?

3. What else do we need to know?

4. How do we make sure the results of research are useful for and available to the

region’s decision-makers?

The chapter ends with an update on next steps for assessing impacts from climate

change in the Mid-Atlantic Region.

B. FOUR QUESTIONS

1. What do we know about the impacts of climate change in the watersheds of the

Chesapeake and Delaware Bays?

The Region’s Unique Characteristics

The Mid-Atlantic Region has several characteristics that make its people, economy,

and ecosystems sensitive to climate change. These include:

• Extensive shorelines

• Significant agricultural, forest, and fishery sectors

• A large population

• Historical settlement patterns along waterways

• An economy based on abundant water

• Unique natural resources, such as the Chesapeake Bay
74

The region also has features that may help to make is resilient to climate change.

These include:

• A highly developed, diversified, dynamic economy.

• Significant potential to adapt through technological and institutional change

Major Findings

• The Mid-Atlantic Region is reasonably robust with respect to climate variability.

This conclusion is based on factors such as the region's abundant water resources,

varied ecosystems, diversified economy, and history of managing weather-related

disasters. Working groups representing different sectors (economic growth, industry

and commerce; ecosystems; water resources; natural hazards; human health;

agriculture, forestry and fisheries) potentially vulnerable to climate impacts ranked

climate low in importance relative to factors such as poverty, global market pressures,

and water and air quality. They viewed these other factors as presenting more

immediate, tangible impacts.

• Climate change could have adverse impacts on the region’s people, economy, and

ecosystems. When working groups accepted model-based future climates as indicative

of the futures, climate impacts took on greater importance. Some impacts were judged

to be as important as other major issues that influence the region’s economic and

societal well-being.

• Potential impacts could vary widely by sector depending on the sensitivity of the

sector and the potential for adaptation. The working groups that discussed health,

ecosystems, and recreation expected profound effects in these sectors. Significant sea

level rise would have a marked and extensive impact in the Mid-Atlantic area. In

contrast, the working group for agriculture did not consider this highly adaptable

component of the regional economy to be seriously threatened under the climate

change scenarios. Global markets are likely to be a greater driver for agriculture than

climate. Similarly, the region’s economic growth was not viewed as seriously

threatened under the climate change scenarios adopted for the workshop. This

conclusion largely reflects the working group’s expectation that the regional

economy’s size, diversity, and adaptability make it resilient with respect to the impacts

of climate change. On the other hand, impacts could be substantial and important on

a local scale. This group expressed uncertainty about how factors governing economic

growth, such as water availability and transportation infrastructure, might be affected

by climate change.

• The importance of climate change in influencing the severity or frequency of

natural disasters is unclear. In general, working groups could identify the types of
75

vulnerabilities, but were unable to assess their magnitudes given the uncertainties

inherent in future climate predictions.

2. What strategies can be considered now for reducing vulnerability and taking

advantage of opportunities presented by climate change?

Despite substantial uncertainties about many potential regional impacts from increased

climate variability and change, adaptation strategies can be identified for problems that are

already recognized or that represent a “win-win” approach to climate impacts. These

include:

• Enforcing restrictions on construction and eliminating subsidies that promote rebuilding within areas of high natural hazard risk.

• Expanding the use of warning systems, such as those that activate under conditions

of high heat stress.

• Improving on land-use and drought planning efforts, which will address issues

already of importance in the region whether climate changes are significant or not.

• Instituting flexible strategies for water management across regional or local districts.

While many strategies can be conceived that would reduce existing and expected

stresses, some would have high economic or societal costs. For example, enhancing the

infrastructure for water management through increased storage capacity is one logical

option given the Mid-Atlantic region’s propensity to drought. But increasing concerns

about the environmental implications of dams and reservoirs now require closer

evaluation along with the actual construction and operating costs. Additional analysis can

examine the cost effectiveness of proposed strategies to address current stresses likely to be

exacerbated by expected economic and population growth. Such actions offer benefits of

reducing the region’s vulnerability to climate as a bonus.

3. What else do we need to know?

This chapter lists relatively few identified near-term strategies for adapting to climate

change. A closer look at the suggested strategies suggests important gaps in our knowledge

of how to evaluate alternative approaches to implementing them. Workshop participants

provided valuable perspectives on research needs, but could not be expected to represent

the full range of (admittedly limited) scientific knowledge available for assessing the

regional impacts of climate variability and change. The workshop discussions,

supplemented by the Organizing Committee’s reflections, suggest the following topics as

the highest priority research needs:
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Research Needs: The scientific information available for assessing regional impacts of

climate change and variability is extremely limited. Assessments based on this limited

information could grossly miscalculate either the threat or opportunities to the region.

Essential information for improving the assessment of how the Mid-Atlantic region would

be affected by climate change include:

• how climate change will affect the regional climate (i.e., frequency and intensity of

severe weather, the nature and timing of precipitation events, frequency and

severity of droughts);

• the rate and magnitude of climate change at the scale of public and private decision

makers in climate sensitive sectors (e.g., agriculture, forestry, water supply);

• how climate change will affect the region’s natural resources and ecosystems;

• how climate change will affect the productivity of agriculture, forests, fisheries and

other sectors;

• differences in risk between private and public sector activities;

• differences in risk for different population segments;

• the role of information in initiating responses to minimize risks or maximize

opportunities;

• how institutional and technological change can diminish risks and enhance

opportunities;

• the current state of Mid-Atlantic ecosystems, and the associated monitoring and

modeling of ecosystem changes; and

• expected regional demographic changes.

4. How do we make sure the new knowledge is useful for and available to the region’s

decision-makers? (A summary of workshop rapporteur Baruch Fischhoff’s insights)

• Who wants or needs to know?

The region’s decision-makers range from individual citizens to heads of interstate

compacts. They can be grouped into three categories with respect to regional impacts

from climate variability and change. These categories include those decision-makers who

are 1) likely to experience direct negative impacts, 2) concerned about costs of policies to

reduce the impacts from climate change, or 3) potentially able to benefit from climate

change. The first group includes the energy and chemical industries, government officials,

environmental groups, health care managers, casualty and non-casualty insurers,

infrastructure managers, the travel/recreation industry, and coastal land owners. It also

includes the disadvantaged, who may be more vulnerable to negative impacts. Actions by

many of these same groups could contribute to or complicate the problem, so they might
77

be part of the second group that is especially concerned about the costs of policy proposed

to reduce greenhouse gas emissions or moderate its impacts. People in the third category

might be able to take advantage of new economic opportunities, including those in

agriculture, engineering, and industrial associations.

• What is worth knowing?

A plan for producing and disseminating information on climate variability and change

starts by noting that information needs differ among members of a very diverse audience.

“Broad-band” dissemination can be helpful for a wide audience with general needs, but

“narrow-band” information may be more helpful for a targeted audience with specific

needs. Communication planning should start with a needs assessment that determines

what people already know, explores their trust in scientific and social sources, and

evaluates whether they need information simply to feel informed or for structured

decisions (e.g., to choose an action). If the goal is informed decisions, a value-ofinformation analysis can help identify what information will be most useful to the

decision-makers.

Research shows that decision-makers often are aware that research is available, but

cannot figure out how to make use of it. This suggests the need for affirmative answers to

four questions:

1. Is the research relevant for decisions?

2. Is the research available to decision-makers?

3. Is the research compatible with their existing decision models?

4. Are decision-makers receptive to research?

• How do we make information useful?

Going beyond “business as usual” will be essential to develop an effective regional

strategy for responding to both challenges and opportunities from increased climate

variability and change. It would be easy for climate researchers to say, “too bad we can’t

give them the data they want” when people express discomfort about the many

uncertainties in projecting climate variability and change and their potential impacts.

Policy makers must recognize the need for coordinated research and analysis to fill holes

in the incomplete picture of the climate issue. They also need integrated management

plans so that solutions to one public problem do not exacerbate another. An important

component of a regional strategy is a communication and collaboration infrastructure,

such as that initiated for the Mid-Atlantic Workshop.
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This communication and collaboration infrastructure should:

• Clarify the costs and benefits of climate change

• Show interconnections among different impacts of climate change

• Have the people who will use the information help plan the research, so that the

impacts they care about will be included

• Use multiple communication channels to

• give people reasons to think about and make sense of an issue

• show the links between research results and actions they can take.

C. NEXT STEPS AND UPDATE

What does this all mean for assessing climate change impacts and adaptation strategies

for the Mid-Atlantic Region? We know that climate change will bring ecological and

social impacts, some positive and many threatening, and that these impacts call for

anticipation, evaluation, and amelioration or adaptation. How do we proceed from here?

The complex linkages among causes and regional consequences of climate change

suggest the need for an integrated regional assessment, but integrated assessments easily can

become unmanageable. Thus we need to choose the key elements and linkages for each

assessment component. The bigger the potential costs from climate change, the greater

the value of conducting a careful assessment to avoid poor choices. The long time scales

associated with climate change inherently involve uncertainties about changes in

technology and socioeconomic factors. This suggests an initial focus on climate impacts

and corresponding strategies that might make sense even without climate change.

The September 1997 workshop participants anticipated that the U.S. Global Change

Research Program (USGCRP) would collaborate with federal agencies (represented in the

National Assessment Working Group, NAWG) to sponsor several regional assessments.

They also anticipated that an interdisciplinary National Assessment Synthesis Team

(NAST), with members in academia, government, and the private sector, would draw

upon the assessments to account for regional differences in its synthesis report due to

Congress by January 2000.

With encouragement from USGCRP and the U.S. Environmental Protection Agency

(EPA), Penn State began assembling a multi-disciplinary team of faculty members to lead

the first Mid-Atlantic Regional Assessment (MARA) of Climate Change Impacts. The

region to be assessed was expanded beyond the boundaries of the Chesapeake and

Delaware Bay watersheds, and now includes all or parts of eight states (NY, NJ, PA, DE,
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MD, WV, VA, and NC) and the District of Columbia. A draft preliminary MARA report

will be ready by April 1999 to meet the NAST schedule.

Penn State’s approach is based on a framework developed by its Center for Integrated

Regional Assessment (CIRA), as shown in Figure 6, and models such as the one they

developed for the Susquehanna River Basin assessment. NAST and NAWG are

recommending specific global climate models (GCMs) and socioeconomic projections, to

enable aggregation across the regional assessments. Penn State also will use its own

empirical downscaling and nested GCM/mesoscale models, which provide finer resolution

for regional assessment. The CIRA framework accommodates an iterative approach, with

increasingly complex quantitative analysis for important components.

Figure 6. Framework for integrated regional assessment.
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The basic questions posed for the September 1997 workshop also will guide MARA:

1. What are the region's current stresses and issues?

2. How would climate change and variability affect these stressors, or

create new ones?

3. What new information is needed to better answer questions 1) and 2)?

4. What are the options for coping with climate-induced stresses?

A major MARA objective is to identify strategies for increasing the region’s resiliency

to climate variability, actions that would reduce negative impacts and take advantage of

opportunities created by climate change. Another objective is to identify research needed

for evaluating adaptation options.

A June 8-9, 1998 researchers’ meeting explored questions raised during Penn State’s

September 1997 workshop and identified available databases and current research useful

for MARA. As a result of this open process, MARA is addressing all five topics being

emphasized in the national synthesis– forests, agriculture, water, coasts, and human

health– as well as cross-cutting issues such as ecosystems. The MARA report will provide

an overview of baseline conditions and how they might be affected by climate change. Indepth case studies will illustrate how impacts will vary within the Mid-Atlantic Region.

For example, the assessment is examining potential consequences of forest changes for the

timber industry as well as for campers or hunters who use forests for recreation. Farming

practices might change with the climate, which could affect the health of waterways, or

the safety of water supplies. Examples of other case studies include: potential impacts on

fishing; ecological and land-use linkages that might increase mosquito-borne or tick-borne

diseases; community water supply managers’ information needs for coping with more

variability in water sources; and the potential for increased damages from sea-level rise

combined with possibly more frequent, more intense storms.

Working groups for each of the five topics include collaborators from other universities

and government. The assessment report will bring together information about diverse

beneficial and detrimental impacts into a picture of the effects on the region as a whole.

More detailed information can be found at http://lumen.deasy.psu.edu/mara/.

To maximize is usefulness, the assessment must go beyond researchers analyzing data

and summarizing results. Input from stakeholders (i.e., potentially interested or affected

parties) can improve the assessment’s usefulness by 1) indicating what information they

need to make more informed decisions related to regional impacts of climate change, 2)

ensuring the assessment is responsive to climate-related concerns most important to the

people who live and work in the region, 3) identifying relevant data not otherwise
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available to the assessment team, and 4) recognizing that their knowledge of regional and

local social, cultural, and political institutions may help prioritize options for building

resilience and flexibility within the region.

To tap this resource, Penn State has set up an Advisory Committee with 45 diverse

stakeholders, 20 representatives of local, state, and federal government, and 12 researchers

(in addition to 15 research collaborators who are working with the core Penn State team).

Many of them participated in an October 19-20, 1998 meeting, during which they

commented on Penn State’s assessment plans and began to explore effective ways to

display future results and strategies for disseminating results. About 20 members of the

Advisory Committee responded to our December 1998 request for feedback on draft

outlines for the working group reports. Their input is helping to shape the continuing

stages of the assessment. At a May 2-3, 1999 meeting, the Advisory Committee will

review draft preliminary assessment results and recommend specifics about how to display

and disseminate the findings. The draft preliminary MARA report, a more complete

report drafted after an additional year of assessment, and supporting documents will be

circulated for review, revised and submitted to the NAST.

The regional assessment is still in its early stages. Much work remains and the

collective wisdom of stakeholders has only begun to be tapped. Still, the focus on the

unique elements of our region is leading the MARA team to clear assessment and research

priorities. Understanding these linkages can reduce the uncertainties in assessing impacts

within the region. Assessment and research have the potential to identify cost-effective,

socially acceptable amelioration and adaptation strategies that will help maintain and

enhance the economic and societal vitality of the Mid-Atlantic Region.
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APPENDIX

Web Site

Much of the material in this report also is available on our web site for the September

1997 workshop:

www.essc.psu.edu/ccimar

(The “essc” stands for one of our sponsors: Penn State’s Earth System Science Center.

The last acronym can be remembered as representing “Climate Change in Mid-Atlantic

Region.”) The printed report integrates material on the web site and adds background

material about the watersheds for the Chesapeake and Delaware Bays.

In turn, the web site has information not printed in this report. The web site

information has been set up so that it is easy to download for your use. Major additions in

the web site include summaries of agenda presentations:

• Kent Mountford, “Chesapeake: History from a Different Perspective”

• Plenary Session on Variability in Today’s Climate

• Plenary Session on Climate Change and Regional Impacts

• Plenary Session on How the News Media Report on Environmental Issues

• Synthesis Plenary Session

Perhaps most important, the web site has the complete text and figures from the

workshop’s Public Address by Joel Scheraga, “Climate Change: What Does It Mean For

You?”

Other web site items include:

• Titles of the posters presented by workshop participants. Abstracts are on the web

site for many of the posters, with full text for a few of them.

• A photo gallery showing most of the workshop organizers and participants, in

working group and plenary sessions

• Video clips of the campus and four workshop speakers

• Letter from Vice President Gore

• Links to related sites
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Steering Committee Members

Janine Bloomfield

Environmental Defense Fund

Dan Botkin

Department of Biology

George Mason University

Irene Brooks

Pennsylvania Department of

Environmental Protection

John Carberry

DuPont

Charles Carson, III

U.S. Steel Group, USX Corporation

Tom Cronin

U.S. Geological Survey

Joanne Denworth

Pennsylvania Environmental Council

Pat Devlin

Alliance for the Chesapeake Bay

Gerald Hansler

Delaware River Basin Commission

Laurence Kalkstein

Department of Geography

University of Delaware

John McSparran

Susquehanna River Basin

Jon Plaut

NAFTA Environmental Commission

Joel Scheraga

U.S. Environmental Protection Agency

Climate and Policy Assessment Division

Gwynne Schultz

Maryland Department of Natural Resources

Coastal Zone Management Division

David Schwarzwaelder

Columbia Gas of Pennsylvania & Maryland

Michael Slimak

U.S. Environmental Protection Agency

National Center for Environmental Assessment

Bud Ward

Environmental Health Center

National Safety Council
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List of Participants

Richard Artz

National Oceanic and Atmospheric Administration

Air Resources Lab

Allan Auclair

Science & Policy Associates, Inc.

Mark Ayers

U.S. Geological Survey

Timothy Banfield

Allegheny Power

Thomas Barnwell, Jr.

U.S. Environmental Protection Agency

Eric Barron

Earth System Science Center

Pennsylvania State University

Ana Barros

Department of Civil Engineering

Pennsylvania State University

Brad Bell

WJLA TV-7

Chris Bernabo

Science & Policy Associates, Inc.

Rosina Bierbaum

Executive Office of the President

Donald Boesch

Center for Environmental Science

University of Maryland

Dan Botkin

Department of Biology

George Mason University

Irene Brooks

Pennsylvania Dept. of Environmental Protection

Arthur Butt

Virginia Department of Environmental Quality

Michael Calaban

New York State Dept. of Environmental Conservation

John Carberry

DuPont

Jeff Carmichael

Center for Integrated Regional Assessment/Earth

System Science Center

Pennsylvania State University

Charles Carson, III

U.S. Steel Group, USX Corporation

Lynne Carter

Graduate School of Oceanography

University of Rhode Island

Betty Conner

League of Women Voters of Pennsylvania

Robert Crane

Associate Dean for Education

Pennsylvania State University

Tom Cronin

U.S. Geological Survey

Pierre Crosson

Resources for the Future

Benjamin DeAngelo

Natural Resources Defense Council
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Joanne Denworth

Pennsylvania Environmental Council

John Dutton, Dean

College of Earth & Mineral Sciences

Pennsylvania State University

William Easterling

Department of Geography

Pennsylvania State University

Peter Eisenberger

Columbia Earth Institute

Columbia University

Jenni Evans

Department of Meteorology

Pennsylvania State University

Baruch Fischhoff

Department of Engineering & Public Policy

Carnegie Mellon University

Ann Fisher

Dept. of Agricultural Economics & Rural Sociology

Pennsylvania State University

Ken Frederick

Resources for the Future

Richard Fromuth

Delaware River Basin Commission

William Gburek

U.S. Department of Agriculture

Lewis Gilbert

Columbia Earth Institute

Columbia University

Caren Glotfelty

School of Forest Resources

Pennsylvania State University

Richard Hallgren

American Meteorological Society

Carol Hartgen

U.S. Department of the Interior

Minerals Management Service

Wanda Haxton

U.S. Environmental Protection Agency

Climate Policy & Assessment Division

Gil Hirschel

Susquehanna River Basin Commission

Joseph Hoffman

Pennsylvania Department of Environmental

Protection

John Hom

U.S. Department of Agriculture Forest Service

Tom Horton

Baltimore Sun

Susan Hunter

National Aeronautics & Space Administration

Goddard Space Flight Center

Greg Jenkins

Department of Meteorology

Pennsylvania State University

Laurence Kalkstein

Department of Geography

University of Delaware

John Karish

National Park Service

John Kermond

National Oceanic and Atmospheric Administration

Office of Global Programs

Richard Kiang

National Aeronautics & Space Administration

Goddard Space Flight Center
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C. Greg Knight

Department of Geography

Pennsylvania State University

Charles Krueger

Department of Agronomy

Pennsylvania State University

Jeff Lawson

WVEC-TV 13

Daniel Leathers

Center for Climatic Research

University of Delaware

Barbara Levinson

U.S. Environmental Protection Agency

Office of Research & Development

Archie McDonnell

Environmental Resources Research Institute

Pennsylvania State University

Edgar Mercado

Maryland Department of the Environment

Kent Mountford

U.S. Environmental Protection Agency

Chesapeake Bay Program

Ray Najjar

Department of Meteorology

Pennsylvania State University

Nancy Parks

Sierra Club

Jonathan Patz

Division of Occupational & Environmental Health

Johns Hopkins School of Public Health

John Paul

U.S. Environmental Protection Agency

Office of Research & Development

Michele Pena

Climate Institute

Theresa Pierno

Maryland Department of Natural Resources

Rick Piltz

U.S. Global Change Research Program

Jon Plaut

NAFTA Environmental Commission

Robert W. Popham

Maryland Space Grant Consortium

John Reilly

U.S. Department of Agriculture

Bruce Richards

Center for the Inland Bays

Chester Ropelewski

National Oceanic and Atmospheric Administration

Climate Prediction Center

Adam Rose

Dept. of Energy, Environmental, & Mineral Economics

Pennsylvania State University

Stephen Runkle

Pennsylvania Dept. of Environmental Protection

Joel Scheraga

U.S. Environmental Protection Agency

Climate and Policy Assessment Division

Kyle Schilling

Institute for Water Resources

Gwynne Schultz

Maryland Department of Natural Resources

Coastal Zone Management Division
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Peter Schultz

Earth System Science Center

Pennsylvania State University

David Schwarzwaelder

Columbia Gas of Pennsylvania & Maryland

George Segelken

CIGNA Property & Casualty

Jim Shortle

Dept. of Agricultural Economics & Rural Sociology

Pennsylvania State University

Kelly Sims

Ozone Action

Michael Slimak

U.S. Environmental Protection Agency

National Center for Environmental Assessment

Peter Sousounis

College of Engineering

University of Michigan

Robert Steele

College of Agricultural Sciences

Pennsylvania State University

William Stevens

Science News Department

The New York Times

Chung-Hsiung Sui

National Aeronautics & Space Administration

Goddard Space Flight Center

John Topping, Jr.

Climate Institute

Lawrence Tropea, Jr.

Global Environmental Services

AMP Incorporated

David Trostle

Pennsylvania Dept. of Environmental Protection

Dennis Trout

U.S. Global Change Research Program

Anthony Vega

Dept. of Anthropology, Geography & Earth Science

Clarion University

Bud Ward

Environmental Health Center

National Safety Council

Fred Wertz

Pennsylvania Department of Agriculture

Brent Yarnal

Department of Geography

Pennsylvania State University
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Working Group Questions

For all participants:

1. How important is climate variability compared to other current stresses and sources of

vulnerability?

2. What kinds of physical, social, and economic changes and consequences do you expect

if current climate projections are correct? Are the impacts positive or negative? How

important are these changes relative to other future sources of stress and vulnerability?

3. Is adequate information available to assess the importance of climate variability and

change for the sector(s) and to form adaptation and management strategies? What are

the most important unmet information needs?

4. What regional adaptation and management strategies would help in adjusting or

counteracting the impacts of climate variability and climate change?

5. Which strategies are most cost effective? Best for social equity? Robust to the

uncertainty concerning where, when, and to what degree climate change and

variability will occur?

6. What public policy actions or other outside assistance could help implement these

strategies?

For leadership teams (long set):

1. Past and current climatic impacts

How important have the effects of climate variability and climate change been on the

sector(s) over the last few decades and how important are they currently?

What major changes (i.e., social, economic, technological, and other environmental

issues) in the sector(s) are occurring that are not related to human-induced climate change

and variability?

How do current climate variability and climate change compare in importance with

other current stresses and sources of vulnerability?

2. Future climatic impacts

What major future changes (i.e., social, economic, technological, and other

environmental issues) in the sector(s) are expected but are not related to human-induced

climate change and variability?
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What kinds of physical, social and economic changes and consequences in the sector(s)

do you expect as a result of human-induced climate change, if current climate projections

are correct?

If current climate model projections are correct, how important is future climate

change for the sector(s), relative to other future sources of stress and vulnerability?

Evaluate the degree to which the climate-induced impacts and consequences may be

positive or negative for specific groups and for society as a whole.

3. Information issues

What kinds of information are needed to ensure a reasonable assessment of the

importance of climate variability and climate change for the sector(s)?

What kinds of information are needed to form adaptation and management strategies

in the face of possible climatic variability and climate change?

Do you believe that this information is available but poorly communicated or that

new research or partnerships are required to obtain it?

How can the media contribute to greater public understanding of scientific study

results about climate change? How can the media contribute to public understanding of

long-term trends (in contrast to extreme events)? How can government agencies

contribute in these areas? The scientific community? Private industry?

4. Strategies and policy issues

What regional adaptation, management, and economic strategies can be used in the

sector(s) for adjusting to or counteracting the impacts of climate variability and climate

change? Can climate variability be buffered to reduce impact severity?

How are the strategies affected by uncertainty concerning where, when, and to what

degree climate change and variability will occur? Are there any “no regrets” or “low

regrets” strategies?

How cost effective are the strategies?

What are the societal impacts of the strategies? Who will benefit and who will lose?

In what ways are existing institutions well, or poorly, structured for facing potential

climate change? Are there significant institutional or other barriers to these strategies?

How could these be removed? Are there significant public policy actions or other outside

assistance that could ease implementation of these strategies?
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Workshop Agenda
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Letter from Vice President Gore