Understanding the Science of Climate Change

Talking Points – Impacts to Alaska Boreal and Arctic

Natural Resource Report NPS/NRPC/NRR—2010/224

National Park Service

U.S. Department of the Interior

Natural Resource Program Center
ON THE COVER

An autumn susnet over the bunkhouse at Serpentine Hot Springs, Bering Land Bridge National Preserve; NPS photo.
Understanding the Science of Climate Change

Talking Points – Impacts to Alaska Boreal and Arctic

Natural Resource Report NPS/NRPC/NRR—2010/224

Caroline Jezierski

Kenai Fjords National Park

500 Adams Street, Suite 103

Seward, AK 99664-1727 

Rachel Loehman

Rocky Mountain Research Station

Fire Sciences Laboratory

5775 West US Hwy 10

Missoula, MT 59808-9361

Amanda Schramm

National Park Service

1201 Oakridge Drive

Fort Collins, CO 80525

With special thanks to the US Forest Service’s Rocky Mountain Research Station and contributions from (in alphabetical order): 

Nancy Fresco, Fritz Klasner, Maggie MacCluskie, Don Callaway, Philip Martin, John Morris, Karen Murphy, Jeff Rasic, Bud Rice, 

Bob Winfree and Leigh Welling. Layout and design: Sara Melena, Angie Richman, Caitlin Shenk, and Katherine Stehli.

July 2010

U.S. Department of the Interior

National Park Service

Natural Resource Program Center

Fort Collins, Colorado
The Natural Resource Publication series addresses natural resource topics of interest and applicability to a broad 

readership in the National Park Service and to others in the management of natural resources, including the scientific 

community, the public, and the NPS conservation and environmental constituencies. Manuscripts are peer-reviewed 

to ensure the information is scientifically credible, technically accurate, appropriately written for the intended audience, and is designed and published in a professional manner.

Natural Resource Reports are the designated medium for disseminating high priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain 

NPS policy considerations or address sensitive issues of management applicability. Examples of the diverse array 

of reports published in this series include vital signs monitoring plans; monitoring protocols; “how to” resource 

management papers; proceedings of resource management workshops or conferences; annual reports of resource 

programs or divisions of the Natural Resource Program Center; resource action plans; fact sheets; and regularly-published newsletters.

Views, statements, findings, conclusions, recommendations and data in this report are solely those of the author(s) 

and do not necessarily reflect views and policies of the U.S. Department of the Interior, National Park Service. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the 

National Park Service.

This report is available from the Natural Resource Publications Management website:

( http://www.nature.nps.gov/publications/NRPM )

Please cite this publication as:

Jezierski, C., R. Loehman, and A. Schramm. 2010. Understanding the science of climate change: Talking points - 

impacts to Alaska Boreal and Arctic. Natural Resource Report NPS/NRPC/NRR—2010/224. National Park Service, 

Fort Collins, Colorado.

NPS 953/104874, July 2010
Contents 

Introduction ............................................................................................................................................................1

Climate Change Impacts to Alaska Boreal and Artic ............................................................................................... 2

Summary.........................................................................................................................................................................................2

List of Parks and Refuges .............................................................................................................................................................3

Sectors:

 Temperature............................................................................................................................................................................4

 The Water Cycle .....................................................................................................................................................................6

 Vegetation................................................................................................................................................................................8

 Wildlife .................................................................................................................................................................................. 10

 Disturbance........................................................................................................................................................................... 14

 Cultural Resources............................................................................................................................................................... 16

 Visitor Experience.................................................................................................................................................................17

No Regrets Actions .................................................................................................................................................18

Global Climate Change...........................................................................................................................................21

Sectors:

 Temperature and greenhouse gases....................................................................................................................................21

 Water, Snow, and Ice............................................................................................................................................................24

 Vegetation and Wildlife .......................................................................................................................................................26

 Disturbance...........................................................................................................................................................................29

References ........................................................................................................................................................... 30
National Park Service 1

Purpose

Climate change presents significant risks to our nation’s natural 

and cultural resources. Although climate change was once believed to be a future problem, there is now unequivocal scientific evidence that our planet’s climate system is warming (IPCC 

2007a). While many people understand that human emissions 

of greenhouse gases have contributed to recent observed climate changes, fewer are aware of the specific impacts these 

changes will bring. This document is part of a series of bioregional summaries that provide key scientific findings about 

climate change and impacts to protected areas. The information 

is intended to provide a basic understanding of the science of 

climate change, known and expected impacts to resources and 

visitor experience, and actions that can be taken to mitigate and 

adapt to change. The statements may be used to communicate 

with managers, frame interpretive programs, and answer general questions to the public and the media. They also provide 

helpful information to consider in developing sustainability 

strategies and long-term management plans. 

Audience

The Talking Points documents are primarily intended to provide 

park and refuge area managers and staff with accessible, up-todate information about climate change and climate change impacts to the resources they protect. 

Organizational Structure

Following the Introduction are three major sections of the 

document: a Regional Section that provides information on 

changes to Alaska Boreal and Artic, a section outlining No 

Regrets Actions that can be taken now to mitigate and adapt 

to climate changes, and a general section on Global Climate 

Change. The Regional Section is organized around seven types 

of changes or impacts, while the Global Section is arranged 

around four topics.

Regional Section

•	 Temperature 

•	 The Water Cycle (including snow, ice, lake levels, sea levels 

and sea level rise, and ocean acidification)

•	 Vegetation (plant cover, species range shifts, and phenology)

•	 Wildlife (aquatic, marine, and terrestrial animals, range shifts, 

invasive species, migration, and phenology)

•	 Disturbance (including range shifts, plant cover, plant pests 

and pathogens, fire, flooding, and erosion)

•	 Cultural Resources

•	 Visitor Experience

Global Section

•	 Temperature and Greenhouse Gases

•	 Water, Snow, and Ice

•	 Vegetation and Wildlife

•	 Disturbance

Information contained in this document is derived from the 

published results of a range of scientific research including 

historical data, empirical (observed) evidence, and model projections (which may use observed or theoretical relationships). 

While all of the statements are informed by science, not all statements carry the same level of confidence or scientific certainty. 

Identifying uncertainty is an important part of science but can 

be a major source of confusion for decision makers and the 

public. In the strictest sense, all scientific results carry some 

level of uncertainty because the scientific method can only 

“prove” a hypothesis to be false. However, in a practical world, 

society routinely elects to make choices and select options for 

actions that carry an array of uncertain outcomes. 

The statements in this document have been organized to help 

managers and their staffs differentiate among current levels of 

uncertainty in climate change science. In doing so, the document aims to be consistent with the language and approach taken in the Fourth Assessment on Climate Change reports by the 

Intergovernmental Panel on Climate Change (IPCC). However, 

this document discriminates among only three different levels 

of uncertainty and does not attempt to ascribe a specific probability to any particular level. These are qualitative rather than 

quantitative categories, ranked from greatest to least certainty, 

and are based on the following: 

•	 “What scientists know” are statements based on measurable 

data and historical records. These are statements for which 

scientists generally have high confidence and agreement 

because they are based on actual measurements and observations. Events under this category have already happened or 

are very likely to happen in the future.

•	 “What scientists think is likely” represents statements beyond 

simple facts; these are derived from some level of reasoning 

or critical thinking. They result from projected trends, well 

tested climate or ecosystem models, or empirically observed 

relationships (statistical comparisons using existing data). 

•	 “What scientists think is possible” are statements that use a 

higher degree of inference or deduction than the previous 

categories. These are based on research about processes that 

are less well understood, often involving dynamic interactions among climate and complex ecosystems. However, 

in some cases, these statements represent potential future 

conditions of greatest concern, because they may carry the 

greatest risk to protected area resources. 

I. Introduction 
2 Climate Change Talking Points NPS/FWS—2010

II. Climate Change Impacts to Alaska Boreal and Arctic Bioregions

The Boreal and Arctic Bioregion that is discussed in this 

section is shown in the map 

to the right. A list of parks 

and refuges for which this 

analysis is most useful is included on the next page. To 

help the reader navigate this 

section, each category is designated by color-coded tabs 

on the outside edge of the 

document.

Summary

Alaska is a huge state spanning 375 million acres and occupying nearly one-fifth of the land area of the contiguous 48 states. 

More than half of the coastline of the entire United States is in Alaska. Due to the great size and geographically diverse nature 

of Alaska, two bioregional documents were produced: “Boreal and Arctic” and “Alaska Maritime and Transitional.” In Alaska, 

the vast majority of the land is public; with approximately 222 million acres (approximately 60%) designated federal lands and 

another 90 million acres (approximately 24%) in state ownership. There are 17 National Park Service (NPS) areas in Alaska 

covering over 54 million acres; this represents two-thirds of the land in the entire National Park system. Wrangell-St. Elias is the 

largest NPS unit at over 13 million acres in size. There are 16 National Wildlife Refuges in Alaska totaling over 76 million acres, 

representing approximately 80% of the entire National Wildlife Refuge system. The two national forests in Alaska encompass 

nearly 22 million acres; Tongass National Forest is the largest United States Forest Service unit, with nearly 17 million acres. The 

Bureau of Land Management manages almost 78 million acres in Alaska. 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
National Park Service 3

List of Parks and Refuges

Summary Continued

Climate changes in the Boreal and Arctic bioregion include increased mean, minimum, and maximum annual and seasonal 

temperatures, especially in the spring and winter, resulting in earlier spring budding, an increase in the length of the growing 

season, and an increase in the annual numbers of snow-free and frost-free days. Hotter, drier summers contribute to drought 

stress in the boreal forest, leading to reduced tree growth, changes in rates of carbon sequestration, and increased disturbance 

from fires and insect outbreaks. In addition, shrub expansion into Arctic tundra is altering forage availability for caribou and 

other wildlife. Additional climate change impacts include changes to regional hydrology, including decreased spatial extent 

of glaciers and sea ice, and increased sea surface temperatures. Secondary effects include shifts in plankton availability in the 

Bering Sea, which in turn is impacting the distribution and population dynamics of fish, seabird, and wildlife species. 

U.S. National Park Service Units

•	 Bering Land Bridge NPR

•	 Cape Krusenstern NM

•	 Denali NP & NPR

•	 Gates of the Arctic NP & NPR

•	Inupiat Heritage Center 

•	 Kobuk Valley NP

•	 Noatak NPR

•	 Wrangell-St. Elias NP & NPR

•	 Yukon - Charley Rivers NPR

U.S. Fish & Wildlife Service Units

•	 Arctic NWR

•	Innoko NWR

•	 Kanuti NWR

•	 Koyakuk NWR

•	 Nowitna NWR

•	 Selawik NWR

•	Tetlin NWR

•	Togiak NWR

•	 Yukon Delta NWR

•	 Yukon Flats NWR

NM National Monument

NP National Park

NPR National Preserve 

NWR National Wildlife Refuge

Acronym Unit Type

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
4 Climate Change Talking Points NPS/FWS—2010

0.14°C (0.25°F) in the summer and 0.24°C 

(0.43°F) in the winter (Keyser et al. 2000). 

•	 Alaska-wide minimum temperatures have 

warmed proportionally more than mean or 

maximum temperatures; the lowest (coolest) temperatures have warmed more than 

the highest (hottest) temperatures. (Stafford et al. 2000; Alaska Climate Research 

Center, Geophysical Institute 2009). 

Per decade average minimum temperatures increased by 0.23°C (0.41°F) during 

the summer and 0.35°C (0.63 °F) during the winter, and spring minimum temperaturesincreased an average of 0.47°C 

(0.85°F) per decade. (Keyser et al. 2000).

•	 Alaska’s mean annual diurnal temperature 

ranges (difference between maximum and 

minimum temperatures) decreased 0.3°C 

(0.5°F) between 1949 and 1998. In the 

Interior and the Arctic, the winter mean 

diurnal temperature ranges decreased by 

0.6 to 0.9°C (1.1 to 1.6°F) respectively. 

Both summer and autumn showed slight 

increases in mean diurnal temperature 

ranges (Stafford et al. 2000).

•	 Fairbanks experienced a general warming 

trend from 1906 to 2006. The mean annual temperature increased 1.4°C (2.5°F) 

compared to 0.8°C (1.44°F) worldwide. 

Temperatures increased during the winter, spring, and summer seasons, while 

autumn showed a slight decrease in temperature. The number of days with very 

low temperatures (less than -40°C) has 

decreased, on average, from 14 to 8 days 

annually (Wendler and Shulski 2009).

•	 An increase in the length of the growing 

season in Fairbanks was observed from 

1906 to 2006. For the 0°C (32°F) freezing 

point, the growing period increased from 

85 to 123 days (45%). At -2.2°C (28°F), the 

temperature threshold for frost-resistant 

plants, the growing season increased from 

ll3 to 144 days, or 27% (Wendler and Shulski 2009).

•	 From 1982 to 2008, summer tundra land 

temperatures, as measured by the summer 

warmth index (sum of the monthly mean 

temperatures that are above freezing), increased 24% for the northern hemisphere 

as a whole; the North America Arctic tunThis weather station in Denali 

National Park is used to monitor temperature and other climatic factors; NPS photo.

A. TEMPERATURE

What scientists know....

•	 Mean annual temperatures in Alaska increased an average 1.7°C over the last six 

decades, with a general warming rate of 

0.16 to 0.37°C per decade from 1951 to 

2001 (Alaska Climate Research Center et 

al. 2009; Hartmann and Wendler 2005).

•	 From 1949 to 2009, regional mean annual 

temperatures for the Arctic, Interior, and 

West Coast of Alaska increased by 1.4 

to 2.5°C (2.5 to 4.5°F) and the greatest 

change in mean seasonal temperatures (2.3 

to 4.9°C, 4.1 to 8.8°F) was observed in the 

winter (Alaska Climate Research Center 

2010).

•	 Maximum temperature increases were 

observed throughout Alaska; the greatest 

increases were observed during the spring 

with an average of 0.46°C (0.83°F) per 

decade (Keyser et al. 2000). Average maximum temperatures increased per decade 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
National Park Service 5

the 21st century, with the most significant 

changes in the northwest U.S. (Meehl et 

al. 2004).

•	 Models predict that the mean number of 

frost days in the Boreal and Arctic bioregion will decrease by between 20 and 40 

days per year by the end of the 21st century, as compared with trends from 1961 

to 1990 (Meehl et al. 2004).

•	 Models based on mid-range (A1B) emissions scenarios project that by 2091, average monthly temperatures for Barrow, 

where the Inupiat Heritage Center is located, will increase by 1.1 to 2.8°C (2.0°F 

to 5.0°F) during the summer months and 

8.9 to 14.6°C (16.0 to 26.0°F) during the 

winter months (Scenarios Network for 

Alaska Planning 2009a). These models also 

predict that temperatures in Kotzebue, the 

closest large community to the Western 

Arctic National Parklands, will increase 3 

to 5 times more in the winter than in the 

summer by the year 2091. Two months 

that historically had average temperatures below freezing will increase to above 

freezing by 2061 (Scenarios Network for 

Alaska Planning 2009b).

What scientists think is possible....

•	 Annual mean temperatures are predicted 

to increase at an average rate of 0.56°C 

(1.0°F) per decade for Alaskan National 

Park units and the Yukon Flats National 

Wildlife Refuge. Average winter temperatures for the national park units are predicted to increase by 5.6 to 7.8°C (10.1 to 

14.0°F) by 2080 (Rupp and Loya 2009a, b, 

c, d, e, f, g, h). 

•	 Modeling indicates that average annual 

temperatures in the Bering Land Bridge 

National Preserve, Denali National Park 

and Preserve, Yukon-Charley Rivers National Preserve, and Yukon Flats National 

Wildlife Refuge are predicted to shift from 

below freezing to above freezing during 

the 21st century (Rupp and Loya 2009; 

Rupp and Loya 2009a, b, h).

•	 By the end of the century, the growing 

season in Yukon Flats National Wildlife 

Refuge could be 1 month longer than it is 

currently (Rupp and Loya 2009).

Comparison photos of Teklanika 

Glacier in Denali National Park 

show glacial retreat.; NPS photo.

dra experienced a 30% increase in summer 

land temperatures (Walker et al. 2009).

•	 Since the mid-1960s, the melt date (date of 

final snowmelt) in northern Alaska has advanced by about 8 days (Stone et al. 2002). 

•	The majority of Alaskans polled anticipate 

that global climate change will result in 

more comfortable temperatures (Leiserowitz and Craciun 2006).

What scientists think is likely....

•	 Warmer arctic temperatures in spring are 

projected to lead to earlier sea ice breakup; warmer fall temperatures could lead 

to delays in autumnal sea ice development 

(Comiso 2003; Overland et al. 2002).

•	 Models predict an overall decrease in the 

number of frost days (days with a nighttime temperature below 0°C) by the end of 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
6 Climate Change Talking Points NPS/FWS—2010

B. THE WATER CYCLE

What scientists know....

•	 All Alaskan glaciers below ~1500 m 

(4,905ft) in elevation are melting, and 

many of Alaska’s 100, 000 glaciers (including tidewater formations) are retreating 

and/or thinning (Molnia 2007, 2008). In 

Denali National Park and Preserve many 

of the glaciers are retreating an average of 

66 ft per year (Adema et al. 2007). 

•	The melting rate of glaciers throughout 

Alaska has increased in recent decades, 

as has their contribution to sea level rise 

(Dyurgerov and Meier 2000; Larsen et 

al. 2007a). From the mid 1990s to the 

early 2000s, the rate of glacial thinning in 

Alaska tripled compared to the mid 1950s 

to mid-1970s time period; the loss of ice 

during this period was equivalent to nearly 

twice the estimated annual loss of ice from 

the Greenland Ice Sheet. Over the last 

half of the 20th century, Alaska glaciers 

contributed the largest single measured 

glaciological contribution to sea level, with 

a total annual volume change of –52 ± 15 

km3/year (12.3 ± 3.6 miles3) water equivalent, which equates to a rise in sea level of 

0.14mm ± 0.04 mm/year, (0.006 ± 0.002 in/

year). (Arendt et al. 2002). 

•	 Changes in sea ice in both the Arctic Ocean 

and the Bering Sea have been observed; 

for example, ice cover on the Bering Sea 

shelf decreased significantly from 1954 to 

2006 (Mueter and Litzow 2008), and a 

net thinning of the Arctic sea ice by ~0.6m 

(1.97 feet) was observed between 2004 

and 2008. In addition, there has been a 

decrease in the amount of perennial sea 

ice, and the the 2009 summer sea ice minimum was the third-lowest recorded since 

1979, and 2007 was the lowest (Perovich 

et al. 2009).

•	The Arctic Ocean sea ice melt season has 

increased by 6.4 days per decade between 

1979 and 2007 (Hansen 2010). 

•	 Spring break-up on the Tanana River has 

advanced by 0.71 days per decade coinciding with increases in spring surface 

temperature in interior Alaska (80+ years 

of data) (Keyser et al. 2000).

•	 Snow patterns at Barrow, Alaska, have 

changed in the past five decades. From 

1972 to 2000, the duration of the snowfree period increased by 3 to 6 days per decade, and the first week in spring without 

snow cover shifted to 3 to 5 days earlier 

per decade (Dye 2002). In addition, the 

snow melt date has advanced by 8 days 

since the mid-1960s (Stone et al., 2002).

•	 Observed decreases in snow and ice extent 

reduce the albedo (proportion of solar 

radiation reflected by a surface) of the 

surrounding land surface (Richter-Menge 

and Overland 2009). With a reduction in 

the albedo of northern Alaska, both from 

reduction of snow and loss of sea ice, more 

of the sun’s energy will be absorbed rather 

than reflected, creating a positive feedback loop of increasing temperatures. This 

positive feedback leads to more ice melt, a 

delay in fall ice formation, and reduced sea 

ice volume (Francis et al. 2009).

(Top) Ruth Glacier at Denali National Park; NPS photo. (Bottom) 

Sea ice in the Beaufort Sea, in 

the Arctic Refuge coastal plain, 

with the Brooks Range Mountains in the background; USFWS 

photo.

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
National Park Service 7

the mean discharge was observed in North 

American Arctic rivers from 2000 to 2007, 

as compared with the 1973-1999 average 

(Shiklomanov 2009). 

•	 From the 1950s to 2000s, closed-basin 

ponds in boreal regions decreased in area 

and number; the area of subarctic ponds 

decreased by 4 to 31%, whereas Arctic 

ponds did not show a marked change in 

pond area (Riordan et al. 2006). During the 

same time period, 22 out of 24 ponds being 

studied near Council, Alaska decreased in 

area (Yoshikawa and Hinzman 2003). 

•	In 2004, a retrogressive thaw slump (slope 

failure resulting from thawing permafrost) 

occurred on the upper Selawik River in 

the Selawik National Wildlife Refuge as 

a result of thawing permafrost. The Selawik slump is the largest of its kind in 

North America. It is increasing in size and 

projected to increase for decades. The 

slump covers an area of 8.7 acres and as 

of 2009 has deposited approximately 12.6 

million ft3 of sediment into the Selawik 

river (Crosby 2009). 

•	 As permafrost thaws, thermokarst features, such as ponds, form. The thawing 

also results in an increase in surface water 

runoff, increased ocean storage of freshwater, increased albedo, and an increase in 

the depth of the active layer of the permafrost (soil overlaying the permafrost that 

experiences seasonal thawing and freezing) (Francis et al. 2009).

What scientists think is likely....

•	 Acidification of Alaska’s oceans is occurring at a faster rate than in tropical waters. 

Cold water, shallow continental shelves, 

and high productivity of Alaska’s marine 

waters facilitate the increased absorption of CO2, reduced deep water circulation, and decomposition, respectively; 

all contribute to increased acidification 

compared to other regions (University of 

Alaska Fairbanks 2009).

•	 Models predict that precipitation will increase in all national park units in this 

bioregion from 12 to 33% in the summers and 25 to 65% in the winter months. 

•	In western and interior Alaska, mean annual precipitation increased by 7 to 9% 

between 1949 and 1998. Precipitation in 

western Alaska increased by 25% in winter, 21% in autumn, and 17% in spring; 

summer precipitation decreased by 11%. 

In the interior, autumn precipitation increased by 19%, with slight increases during the other seasons (Stafford et al. 2000).

•	In the Arctic, the mean annual and seasonal precipitation decreased significantly 

between 1949 and 1998. Annual precipitation decreased by 36%, with the greatest 

decrease observed in the winter (106%) 

and the least decrease in the summer 

(16%) (Stafford et al. 2000). 

•	 Warmer temperature and altered precipitation patterns are leading to an increase 

in the average annual discharge of fresh 

water from rivers to the Arctic Ocean, 

ultimately contributing to sea level rise. 

A 7% increase in discharge was observed 

from 1936 to 1999 for the six largest Eurasian rivers (Peterson et al. 2002). From 

2000–2007, a 10% increase was observed 

in the rate of fresh water discharge, as 

compared with average discharges from 

1936 to 1999. Similarly, a 6% increase in 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

Aerial photos show ponds 

shrinking over time due to increased evaporation and permafrost thawing. Copyright Riordan et al. 
8 Climate Change Talking Points NPS/FWS—2010

Due to increased evapotranspiration (the 

transport of water into the atmosphere 

from surfaces, including soils and vegetation) from temperature increases and 

lengthened growing seasons, summer and 

fall seasons will be drier than they are currently (Rupp and Loya 2009a, b, c, d, e, f, g, 

h). By 2035, Yukon Flats National Wildlife 

Refuge is predicted to be 10% drier; by 

2075, 25% drier in summer and fall (Rupp 

and Loya 2009).

•	 Evidence from studies conducted in southeast Alaska indicates that as watersheds 

become deglaciated and plant succession 

occurs, inputs of organic carbon and inorganic nitrogen into streams will be altered, 

thereby changing the land-to-ocean fluxes 

of nutrients (Hood and Durelle 2008). 

•	 As temperatures increase in the Arctic, the 

sea ice extent decreases. Reduced sea ice 

extent will have an effect on land temperature, potentially extending up to 1,500 km 

(930 miles) inland; higher temperatures on 

land will contribute to more rapid permafrost thawing and further loss of sea ice. 

Water vapor will also likely increase as a 

result, leading to increased precipitation 

(Lawrence et al. 2008, Francis et al. 2009).

What scientists think is possible....

•	 Recent projections of the contribution of 

glaciers and ice caps to sea level rise are 

higher than were determined in previous 

assessments. Current projections suggest 

that glaciers and ice caps may exceed or 

equal the contribution of the Greenland 

and Antarctic ice sheets to sea level rise 

throughout the next century; the volume 

of the glaciers and ice caps will be decreased less than 35%, leaving substantial volume for additional future melting 

(Meier et al. 2007). 

C. VEGETATION

What scientists know....

•	 Based on a meta analysis of studies examining phenological shifts (shifts in life 

cycle processes), species at higher latitudes 

are more sensitive to climatic change than 

species that exist at lower latitudes (Root 

et al. 2003).

•	 Climate has demonstrably affected terrestrial ecosystems through changes in 

the seasonal timing of life-cycle events 

(phenology), plant growth responses (primary production), and biogeographic 

distribution (Parmesan 2006; Field 2007). 

Statistically significant shifts in Northern 

Hemisphere vegetation phenology, productivity, and distribution have been observed and are attributed to 20th century 

climate changes (Walther 2002; Parmesan 

and Yohe 2003; Parmesan 2006). 

•	 Between 1980 and 2000, vegetation responses mainly to changes in temperature 

resulted in an observed trend toward earlier spring budburst and increased maximum leaf area at high northern latitudes 

(Lucht et al. 2002). In the Arctic, there 

is evidence of earlier plant greening and 

later plant senescence (seasonal die-off) 

(Griffith et al. 2001, Stow et al. 2003). 

•	 Based on over 40 years of data collected across Alaska, the growing season has 

lengthened by an average of 2.6 days per 

10 years (Keyser et al. 2000). Onset of the 

growing season occurred 5.6 days earlier 

between 1982 and 1991, 3.9 days later between 1991 and 1992 (attributed to the 

eruption of Mount Pinatubo), and 1.7 days 

earlier between 1992 and 1999 (Tucker 

et al. 2001). On average, an advance in 

average leaf onset date of 1.10 days per 10 

years was observed between the 1950s and 

1990s (Keyser et al. 2000). 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

A cottongrass field in Gates of 

the Arctic. Cottongrass is an important food source for arctic 

snow geese; NPS photo. 
National Park Service 9

•	Increases in temperature and CO2 between the 1980s and the 2000s resulted 

in increased photosynthetic activity or 

growth on tundra ecosystems, including 

a 7% increase in Arctic tundra and 11% in 

North American tundra (Goetz et al. 2005; 

Walker et al. 2009).

•	 Net primary production (photosynthesis) 

for both aspen (Populus tremuloides) and 

white spruce (Picea glauca) stands in Alaska and northwestern Canada increased by 

20% with the advance in the start of the 

growing season (Keyser et al. 2000). However, tree-ring records indicate that radial growth in interior white spruce stands 

has decreased with increasing temperature, due to temperature-induced drought 

stress (Barber et al. 2000).

•	Tree growth, measured from tree-ring 

chronologies, increased from 1900–1950 

at almost all sites at and near alpine and 

arctic treelines; significant declines in tree 

growth were common after 1950 in all sites 

but those in the Alaska Range, and declines were most common in the warmer 

and drier sites at or near alpine and arctic 

treeline (Lloyd and Fastie 2002).

•	 Based on current and historical photographs from the Arctic, a widespread 

increase in shrub abundance, primarily 

along hillsides and valleys, occurred from 

the 1940s to 2000s (Sturm et al. 2001; Tape 

et al. 2006). 

•	 Arctic wetland emissions of methane, a 

powerful greenhouse gas, increased by 

31% between 2003 and 2007 due to temperature increases (Bloom et al. 2010).

What scientists think is likely....

•	 Land use changes in the boreal region may 

result in greater soil carbon losses than 

in other areas. If forests are converted 

to agricultural land, the resulting carbon 

losses could induce a positive feedback to 

climatic warming (Grünzweig et al. 2004).

•	In the Arctic, warming air temperatures 

may result in large areas of tundra being 

converted to shrubland, amplified by a 

positive feedback cycle in which shrub 

abundance leads to deeper snow, which 

promotes higher winter soil temperatures, 

greater microbial activity, and more plantavailable nitrogen; high levels of soil nitrogen in turn favor shrub growth the following summer (Sturm et al. 2005).

•	 Drought stress in the boreal forests limits 

carbon uptake. If this trend continues, 

the carbon sequestration capacity of these 

forests may decrease over time (Barber et 

al. 2000).

•	 Modeling exercises indicate that boreal 

tree ecotones exhibit varying responses to 

warming, and therefore treeline advancement will vary spatially and temporally 

(Lloyd et al. 2003).

•	 During nine years of experimental climate 

change manipulations on tundra vegetation, there was a loss of 30 to 50% of the 

plant species being studied; evergreen 

shrubs and understory forbs (rarer species) declined more strongly than other 

species or disappeared completely (Chapin et al. 1995). A ‘‘greenhouse climate” 

simulation also indicates a reduction in 

the areas occupied by forbs, lichens, and 

mosses, and a northward shift of shrubs 

and forested areas, particularly evergreen 

forests (Kaplan et al. 2003).

What scientists think is possible....

•	 All members of the genus Picea except 

P. sitchensis, and Pinus banksiana exhibited stronger-than-expected declines in 

growth rates with warmer temperatures, 

likely due to conditions such as direct 

Aspen production, as well as 

fruit and vegetable production 

has increased with the longer 

growing season. An aspen forest in Yukon Flats National Wildlife Refuge (top); wild berries in 

Innoko National Wildlife Refuge 

(bottom). USFWS photos.

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
10 Climate Change Talking Points NPS/FWS—2010

D. WILDLIFE

What scientists know....

•	 A meta analysis of climate change effects 

on range boundaries in Northern Hemisphere species of birds, butterflies, and 

alpine herbs shows an average shift of 6.1 

kilometers (3.8 miles) per decade northward (or meters per decade upward), and 

a mean shift toward earlier onset of spring 

events (frog breeding, bird nesting, first 

flowering, tree budburst, and arrival of migrant butterflies and birds) of 2.3 days per 

decade (Parmesan and Yohe 2003 ).

•	 An increase in Porcupine caribou calf 

survival observed from 1985 to 1996 can 

be attributed to increased temperatures 

which led to an increase in available forage for female caribou during calving and 

lactation (Griffith et al. 2001; Griffith et al. 

2002). 

•	The body size of masked shrews in Alaska 

increased significantly during the second 

half of the twentieth century. Evidence indicates that warmer winter weather conditions increased the survival rate of shrew’s 

prey (small invertebrates that are sensitive 

to the cold), providing greater food availability for the shrew (Yom-Tov and YomTov 2005).

•	Thirty percent of the Pacific brant (Branta 

bernicla nigricans) population, a migratory 

goose species, now spends their winters in 

Alaska instead of migrating south to Mexico, whereas in the past only 10% of the 

population wintered in Alaska. This shift 

in migration patterns corresponds with 

warming regional temperatures (Ward et 

al. 2009). 

•	 Hatch dates for geese and spectacled eiders on the Yukon-Kuskokwim delta have 

advanced by 5 to 10 days in the past 25 

years. May temperatures, timing of river 

ice breakup, and onset of the snow-free 

period on the tundra are correlated with 

hatch dates (Fischer et al. 2009). 

•	 Both common and thick-billed murres 

(Uria aalge and Uria lomvia, respectively) 

showed population reductions with large 

sea surface temperature shifts in either 

temperature stress, temperature-mediated 

drought stress, and in some cases air pollution. (Lloyd and Bunn 2007).

•	Treelines will advance into areas currently 

occupied by Arctic tundra, altering ecosystem nutrient availability (Burkett et al. 

2005).

•	 A variety of future climate scenarios for 

vegetation distribution in interior Alaska 

show black spruce (Picea mariana) as the 

emergent dominant vegetation type. A scenario of warming coupled with increasing 

wildfire activity resulted in the greatest expansion of black spruce (Calef et al. 2005). 

•	 A model of the effects of climate warming on Arctic plant communities showed 

different responses in the short term (2 

years), longer term (50 to 75 years) and 

at 200 years. After 200 years, community 

composition was not typical of vegetation 

today. The model showed an increase in 

lichen, decrease in sedges, and increases in 

deciduous and evergreen shrubs (Epstein 

et al. 2000).

•	 Models predict that by 2050, warmer, drier 

conditions and associated increased wildfire activity will alter the vegetation composition of Yukon Flats National Wildlife 

Refuge and similar lands. A decline in 

the proportion of mature trees and shift 

to earlier successional plant communities 

was predicted, with deciduous forests replacing white and black spruce forests, 

which could experience a 50% decline 

(Rupp and Loya 2009).

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

The birthing season for moose is 

closely linked to climatic trends 

that provide the most hospitable conditions for bearing and 

rearing young; climate change 

may hinder moose calf survival 

by throwing this relationship 

out of sync. NPS Photo.
National Park Service 11

direction (Irons et al. 2008), but breeding productivity for these seabirds was 

found to be greater when summer sea 

surface temperatures were colder (Byrd et 

al. 2008). 

•	 On the Pribilof Islands in the Bering Sea, 

red-legged and black-legged kittiwakes, 

small seabirds in the gull family, bred earlier and hatch dates progressed by 0.58 to 

0.88 days per year between 1975 and 2006. 

For both species of kittiwakes, productivity appears to be higher when nesting 

begins earlier, when ice is abundant near 

foraging grounds, and in winter and spring 

when sea surface temperatures cool. (Byrd 

et al. 2008). 

•	The Audubon Christmas Bird count, a 

citizen science project, has documented 

that the center of the mean annual latitudinal center of abundance for over 300 

bird species shifted northward nearly 35 

miles (56.4 km) between 1966 and 2004. 

There is a significant correlation between 

temperature trends and shifts in the center 

of abundance. The mean latitudinal shift 

for the pine siskin, a small finch and yearround resident of southern Alaska, was 

approximately 288 miles (463.7km) north 

(Niven and Butcher 2009). 

•	The timing of the plankton bloom in the 

Bering Sea is associated with sea ice edge 

and extent. For example, late seasonal ice 

retreat supports benthic (bottom-dwelling) organisms that are an important food 

resource for marine species. In contrast, 

ice-free periods or early ice retreats support a mainly pelagic (upper ocean) ecosystem (Hunt and Stabeno 2002; Hunt et 

al. 2002; Overland and Stabeno 2004). An 

increase in air and ocean temperatures, 

a reduction in sea ice, reduction benthic 

prey populations, and an increase in pelagic fish resulted in a shift in marine mammal population distributions (Grebmeier 

et al. 2006).

•	 From 1982 to 2006, fish and invertebrate 

species shifted northward an average of 

34 ± 56 km (21 ± 35 miles) in response 

to the northward retreat of the southern 

edge of the cold water pool on the Bering 

Sea shelf. A reorganization of community 

composition was also observed (Mueter 

and Litzow 2008).

What scientists think is likely....

•	 Changes to the terrestrial and aquatic species compositions in parks and refuges are 

likely to occur as ranges shift, contract, or 

expand. Rare species and/or communities 

may be at further risk, and additional species could become rare (Burns et al. 2003).

•	 Parks and refuges may not be able to meet 

their mandate of protecting current species within their boundaries, or in the case 

of some refuges, the species for whose 

habitat protection they were designed. 

While wildlife may be able to move northward or to higher elevations to escape 

some effects of climate change, federal 

boundaries are static (Burns et al. 2003).

•	 Models suggest that the distribution of the 

little brown bat will expand northward in 

Alaska in the next century in response to 

warming temperatures and shorter winters in its current range (Humphries et al. 

2002).

•	 Of the 83 species of arctic and alpine birds, 

72% are considered moderately or highly vulnerable to the impacts of climate 

change, primarily due to their long-distance migrations and their reliance on arctic and alpine habitats that are vulnerable 

to effects of climate change (NABCI 2010).

•	 As trees and shrubs encroach on areas currently occupied by tundra, arctic and alpine breeding birds’ breeding habitats may 

be reduced or eliminated (NABCI 2010). 

Historically, about 10% of the 

Pacific Brant population wintered in Alaska. The number is 

now closer to 30%, and corresponds with warming temperatures. USGS photo.

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

A Bluethroat Thrush perched in 

the Yukon Delta National Wildlife Refuge. Over 300 bird species in Alaska shifted their population centers between 1966 

and 2004. USFWS photo.
12 Climate Change Talking Points NPS/FWS—2010

•	 Coastal seabirds such as the arctic ivory 

gull, (Pagophila eburnea), aleutian tern 

(Onychoprion aleuticus), and Kittlitz’s 

murrelet (Brachyramphus brevirostris) 

show medium or high vulnerability to climate change due to their low reproductive potential and their reliance on marine 

food webs that are also threatened by climate change (NABCI 2010).

•	 Kittlitz’s murrelets are closely associated 

with glaciated fjords and coastlines. With 

glacial retreat, important habitats will be 

lost and Kittlitz’s populations may decline 

(USFWS 2006). 

•	Thawing permafrost may result in changes in the distribution and abundance of 

waterfowl, shorebirds, and gulls due to 

shifts in the types and locations of plant 

communities and changes in surface water 

availability; contaminants such as mercury 

and organic pollutants may also be released into the aquatic environment as the 

permafrost thaws, increasing contaminant 

exposure for birds that rely on the marine 

ecosystem for food (NABCI 2010). 

•	 Boreal forest birds will expand into the 

arctic as climate changes, causing new avian communities to develop (NABCI 2010). 

•	 Arctic marine mammals that are closely 

linked to sea ice, such as the polar bear, 

are predicted to be the most sensitive 

to climate change (based on an index of 

population size, geographic range, habitat 

specificity, diet diversity, migration, site 

fidelity, sensitivity to changes in sea ice, 

sensitivity to changes in the food web, and 

maximum population growth potential 

(Laidre et al. 2008). 

•	 As sea surface temperatures change, the 

distribution of plankton and forage fish 

will change and as a result, seabirds and 

marine mammal forage patterns, distribution, and population dynamics change 

(Hunt et al. 2002; Irons et al. 2008, Meehan 

et al. 1999). 

•	In the northern Chukchi Sea and in the 

Canada Basin of the Arctic Ocean, an undersaturation of aragonite (a mineral essential for developing the shells or calcium-carbonate skeletons of some marine 

fauna) has occurred due to ocean acidification and freshwater influx from sea 

ice melting (Bates et al. 2009; YamamotoKawai et al. 2009). Models show that high 

latitude ocean waters could become undersaturated with magnesium-calcite minerals of higher solubility than aragonite in 

less than a few decades due to ocean acidification (Andersson et al. 2008). This undersaturation has potential to cause profound shifts throughout arctic ecosystems, 

and may ultimately affect survival of large 

animals such as walruses, gray whales, and 

some birds as the planktonic and bethic 

organisms they eat become more scarce 

(Bates et al. 2009). 

•	 Ocean acidification is likely more rapid 

and severe in Alaska than in tropical waters, and will make shell building more 

difficult for pteropods, oysters, crabs and 

other shelled marine animals. It will also 

impact growth, reproduction, and survival of many marine organisms, includNearly all threatened spectacled 

eiders spend the winter in a 

small area of ocean and sea ice 

south of St. Lawrence Island 

in the Bering Sea. This picture 

shows tens of thousands of 

spectacled eiders roosting in an 

open lead of the ice pack. USFWS photo. 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
National Park Service 13

ing pteropods, which make up nearly half 

of the pink salmon’s diet (University of 

Alaska Fairbanks 2009). 

•	 Changes in marine community organization in the Bering Sea caused by warming 

climate and associated loss of sea ice will 

alter availability of snow crab and other 

fisheries resources (Mueter and Litzow 

2008) 

What scientists think is possible....

•	 Changing vegetation cover in many park 

areas will affect wildlife species dependent 

on those habitats. Animals may eventually 

occupy landscapes vacated by glacial ice, 

and utilize new alpine lakes after ice is 

gone (Burkett et al. 2005). 

•	The synergism of rapid temperature rise 

and stresses such as habitat destruction 

may disrupt connectivity among species, 

lead to reformulation of species communities, and result in numerous extirpations 

and/or extinctions (Root et al. 2003).

•	The population cycles of birds and their 

prey, such as spruce budworm, will be 

decoupled in some Boreal areas due to 

warming temperatures (Burkett et al. 2005; 

Juday et al. 2004). 

•	 Predicted changes in arctic vegetation 

from tundra to taiga and boreal forest 

could result in millions of geese losing 

nearly half of their breeding habitat (Zöckler and Lysenko 2001).

•	 Glacier ice worm populations, which rely 

on a very limited temperature range, are 

in danger of local extinctions in Denali 

National Park and Preserve and the Alaska 

Range as glaciers melt (Shain 2009).

•	 An analysis of potential climate change 

impacts on mammalian species in U.S. national parks indicates that with a doubling 

of atmospheric CO2, about 8% of current 

mammalian species diversity may be lost 

on average. The greatest losses across all 

parks occurred in rodent species (44%), 

bats (22%), and carnivores (19%). Species 

are projected to decline in direct proportion to their current relative representation within parks. (Burns et al. 2003).

•	The timing and synchrony of birth for 

moose in Denali National Park and Preserve are adaptations to long-term trends 

in climate that provide the most hospitable 

conditions to bear and rear young; climate 

change may decouple this relationship, 

hindering moose calf survival (Bowyer et 

al. 1998). 

•	In 2004, there were three instances of polar bear cannibalism in the Beaufort Sea. 

No other similar instances have been observed during more than 20 years of research, and researchers hypothesize that 

nutritional stresses related to longer icefree seasons may have led to the incidents 

(Amstrup et al. 2006).

•	The health of caribou and reindeer may 

be affected by changes in temperature and 

precipitation patterns. Warming could 

lead to an increase in insects and pests 

known to harass caribou. Changes in the 

freeze/thaw cycle may alter forage availability in late summer and winter which 

could decrease the carrying capacity of 

A bearded seal hauls out on sea 

ice. Sea ice in the Arctic is rapidly decreasing due to warmer 

temperatures (top); Ocean 

acidification will affect the food 

sources of marine mammals like 

walruses (bottom); USFWS photos.

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
14 Climate Change Talking Points NPS/FWS—2010

preferred prey of salmonids, are negatively 

impacted by ocean acidification (University of Alaska Fairbanks 2009).

E. DISTURBANCE

What scientists know....

•	Increases in coastal shoreline erosion rates 

were observed in the Arctic along parts of 

the Alaskan Beaufort Sea. Mean annual 

erosion rates increased from 6.8 meters 

(22.3 ft) per year (1955 to 1979), to 8.7 

meters (28.5 ft) per year (1979 to 2002), 

to 13.6 meters (44.6 ft) per year (2002 to 

2007). Different erosion rates were observed in different coastal ecosystems 

during the earlier years of the study, but 

erosion rates during the later years of the 

study were more uniformly high (Jones et 

al. 2009). 

•	 Average storm power (determined by a 

combination of wind speed and duration) 

along the coast of the Arctic Ocean increased 59% between the study periods of 

1955-1978 and 1979-2001. An additional 

increase of 35% was observed between the 

1979-2001 and 2002-2006 study periods 

(Jones et al. 2009).

•	In interior Alaska, the most extensive wildfires burn during unusually dry years. The 

frequency of unusually dry years increased 

from once or twice a decade in the 1950s 

to several times a decade at the end of 

the 20th century (Kasischke and Turetsky 

2006). 

•	 Shifts in the North American boreal region 

fire regime from the 1960s and 70s to the 

1980s and 90s were characterized by an 

increase in large fire events, resulting in a 

doubling of annual burned area and more 

than a doubling of the frequency of larger 

fire years (>1,000 km2 or 620 mi2) (Kasischke and Turetsky 2006).

•	Tundra fires generally accelerate carbon 

loss due to both direct burning and subsequent warming of soils, causing higher 

rates of decomposition. One study found 

that for at least two decades following a 

tundra fire, the area was a carbon source, 

not sink (Oechel 1999).

caribou and reindeer. Warmer and drier 

summers may reduce the availability of 

succulent forage for reindeer causing nutritional stress (Babcock et al. 1998).

•	 Predicted shifts in forest community in 

Yukon Flats National Wildlife Refuge 

could result in less suitable habitat for 

caribou (fewer spruce forests over 80 years 

old), but potentially increased habitat for 

moose (increased deciduous forest) (Rupp 

and Loya 2009).

•	 A retrogressive thaw slump on the upper Selawik River, Selawik NWR, is above 

spawning habitat for sheefish (Inconnu), 

an important subsistence fish. Sediment 

input from the slump may reduce survival 

of eggs developing in the gravel. Other 

fish habitats in permafrost-dominated areas may be similarly threatened by thaw 

slumps and their associated sediment input into rivers (USFWS 2009).

•	 Fisheries (especially for pink salmon) may 

see a dramatic decrease in productivity 

if pteropods and other crustaceans, the 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

Models project slightly more 

fires and much larger fires in 

Alaska with a warmer climate; 

USFWS photo.
National Park Service 15

•	 A tundra site was monitored at intervals 

up to 24 years following a wildfire. An 

increase in shrub abundance and little recovery of Sphagnum moss or fruticose 

lichens were observed (Racine et al. 2004).

•	 An increase in vascular plant cover and in 

particular shrub cover, was observed on 

several 20+ year old fire sites in Noatak 

National Preserve (Racine et al. 2006). 

•	 Permafrost thickness did not return to its 

pre-fire thickness at several sites following 

a fire on the tundra (Racine et al. 2004).

•	Insect outbreaks increase in frequency 

and severity with warmer temperatures 

(Juday et al. 2004). Warming trends have 

coincided with increases in spruce budworm in Alaska in recent years and suggest 

that populations could continue to move 

northward with continued climate warming (Juday 1998; Juday et al. 2004).

•	The majority of Alaskans polled anticipate that global climate change will cause 

increased flooding, worse storms, fewer 

salmon, and the extinction of the polar 

bear (Leiserowitz and Craciun 2006).

What scientists think is likely....

•	Impacts such as vegetation population 

shifts, major permafrost thawing, soil 

decomposition, and surface subsidence 

have been observed that were observed 

in the decades following a major tundra 

Coastal erosion led to the 

collapse of this house in 

Shishmaref, a Native Alaskan 

community that is seeking to 

relocate due to increasingly 

severe coastal disturbances. NPS 

Photo. 

fire event suggest that major tundra fires 

in other permafrost areas could result in 

similar impacts, which could even accelerate the predicted effects of climate warming (Racine et al. 2004).

•	 Research in Gates of the Arctic National 

Park and Preserve found that fire, in the 

short-term, may be an important tool for 

helping to maintain yellow-cheeked vole 

populations, as fire creates new burrowing 

habitat and aids in the growth of forage 

(Swanson 1997). 

•	 Due to ocean acidification, there has been 

a decrease in sound absorption. Based on 

current projections of future pH values for 

the oceans, a decrease in sound absorption 

of 40% is expected by mid-century (Hester et al. 2008).

•	 As sea ice diminishes, increasing commercial ship traffic through the Bering and 

Beaufort Seas and across the Northwest 

Passage will increase the risk, and potentially the environmental damage, from 

accidents, oil spills, and cargo spills (ACIA 

2004). 

What scientists think is possible....

•	 Ichthyophonus, a fish parasite that causes 

mortality in fish populations and is easily 

and rapidly spread among fishes, infected 

45% of Chinook salmon in the Yukon 

River and about 30% of the salmon in 

the Tanana River between 1999 and 2003. 

Warming water temperatures may have 

contributed to these levels of infection, 

as the parasite was not reported to affect 

salmon in these rivers before 1985 (Kocan 

et al. 2004). 

•	 Model simulations suggest that a warming climate may result in greater number 

of fires and as much as a 22% increase in 

the regional area burned, as the result of 

both increased vegetation flammability in 

direct response to increased temperatures 

and expansion of forested areas into previously treeless tundra (Dale et al. 2001; 

Rupp et al. 2000).

•	 Model projections of wildfire activity in 

the Yukon Flats National Wildlife Refuge estimate that 11,000km2

 (4,228 mi2, or 

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
16 Climate Change Talking Points NPS/FWS—2010

25%) of the refuge will burn by 2040, with 

some areas experiencing multiple fires 

within that time frame. In addition, between 2010 and 2080 70% of the refuge is 

predicted to experience new burns, with a 

total cumulative burned area of 42,000km2 

by 2080 (Rupp and Loya 2009). 

CULTURAL RESOURCES

What scientists know....

•	 Sea level rise, increased storm surges, and 

the impacts of permafrost erosion to infrastructure have begun to impact Native 

Alaskan communities, diverting resources 

from subsistence activities and in some 

cases requiring relocation of entire communities (Callaway 2007).

•	 Relocating indigenous communities represents a large financial cost for governments, but also impacts the communities 

themselves, potentially resulting in loss of 

integral cultural elements such as access 

to traditional use areas for subsistence activities, loss of history and sense of intact 

community, and potential loss of social 

networks and extended kin support (Callaway 2007).

•	In Kotzebue, a mostly native community in northern Alaska, effects of climate 

change have been noticeable, but mixed. 

Changes in temperature, storm surges, and 

ice cover have led to easier whitefish and 

clam harvests, better spotted seal and caribou hunting by boat, easier access to arctic foxes, and better access to driftwood. 

Conversely, these same changes have also 

resulted in a shorter ice fishing season, 

reduced access to and from Kotzebue for 

transfer of goods and services, increased 

erosion and flooding, and dangerous travel conditions associated with thawing or 

incomplete freezing of ice (Whiting 2002).

•	 Some traditional subsistence practices are 

more expensive and time-consuming than 

in the recent past, due to difficult hunting 

conditions associated with climate change 

impacts. These changes can place a strain 

on subsistence communities, and in some 

cases can be a deterrent to engaging in traditional hunting at all; for example, as sea 

ice conditions change, marine mammals 

may follow sea ice retreat, altering their 

distribution and taking them out of range 

for some hunters (Berman and Kofinas 

2004; Callaway 2007; Hanna 2007).

•	 According to the Alaska Department of 

Resources, Division of Lands, the winter 

tundra travel season on the Arctic North 

Slope has decreased from about 200 days 

in the 1970s to about 120 days in the early 

2000s. Reliable travel over the frozen tundra enables natural resource development, 

access to subsistence sites, and travel between villages (Bradwell et al. 2004).

•	The majority of Alaskans polled believe 

that global warming will seriously impact 

their families, communities, plants, and 

animals. Many believe that it will have 

serious impacts to Alaska within a decade 

(Leiserowitz and Craciun 2006).

What scientists think is likely....

•	 As glaciers and ice melt, cultural resources 

may be uncovered. Artifacts have been 

recovered from ice patches in WrangellSt. Elias National Park. For example, five 

prehistoric sites were identified that contained artifacts ranging in age from 370 to 

2880 years before present. Such artifacts 

can provide unprecedented glimpses into 

the lives of ancient people (Dixon et al. 

2007). 

•	 Subsistence communities have expressed 

concerns about increased pollution and 

its potential effects on the natural environment’s ability to respond to climate 

change. For example, because heavy metals and other contaminants bio-accumuTemperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience

(Top) Children fishing at Kenai 

National Wildlife Refuge. (Bottom) Subsistence hunting is 

subject to changes caused by 

climate shifts. Some game may 

become easier to hunt, and others may become harder to hunt 

using traditional practices. USFWS photos.
National Park Service 17

late up the food chain, there are concerns 

that marine mammals and other animals 

harvested for subsistence could be sources of contaminants for hunters and their 

families as changes in circulatory patterns 

of water and air bring contaminants into 

the natural system (Callaway 1999). Researchers have found contaminants and 

heavy metals in animals harvested for subsistence in the Arctic (Cooper et al. 2000; 

Dehn et al. 2006).

What scientists think is possible....

•	 Climate change may affect people’s ability to conduct subsistence harvests due to 

changes in wildlife distribution and availability. Subsistence harvesting activities 

are linked to the health of rural residents 

in several ways, including the physical exertion of a hunt that promotes mental and 

physical well being, the nutritional value of 

harvested food items compared to storebought food, and the value of maintaining 

a traditional diet (Callaway 1999).

•	 Modeling of several feedback loops that 

take place within the Arctic hydrologic 

system (including those centered around 

cloud cover, water vapor, surface air temperature, precipitation, sea ice, marine 

productivity, human well-being, and land 

cover) shows that in a seasonally ice-free 

Arctic Ocean model, the complexity of 

the system is greatly reduced, affecting the 

function of the feedback loops and resulting in a decrease in human well-being in all 

scenarios (Francis et al. 2009). 

•	 Some indigenous people in northern 

Alaska are concerned that as polar bears 

have an increasingly difficult time accessing prey and finding appropriate shelter 

for reproduction and protection, they may 

be more likely to approach villages and 

encounter humans. (ACIA 2004).

VISITOR EXPERIENCE

What scientists know....

•	 Glaciers, a main tourist attraction in many 

parks, are disappearing. This is happening 

throughout Alaska, including at national 

parks such as Wrangell St.-Elias, Denali and Kenai Fjords (Adema et al. 2007; 

Dyurgerov and Meier 2000; Larsen et al. 

2007a; Molnia 2007; Rupp and Loya 2009).

•	 With increasing temperatures and more 

snow-free days, the length of the potential 

summer tourist season in Alaska is increasing (Alaska Climate Research Center 2009; 

Dye 2002).

What scientists think is likely....

•	 Locations of climatically ideal tourism 

conditions are likely to shift toward higher 

latitudes under projected change, and as a 

consequence spatial and temporal redistribution of tourism activities may occur. 

The effects of these changes will depend 

greatly on the flexibility demonstrated by 

institutions and tourists as they react to 

climate change (Amelung et al. 2007).

•	Increase in coastal erosion along the Bering Sea and Arctic Ocean could erode 

coastlines, affecting travel and tourist destinations (Smith and Levasseur 2003).

What scientists think is possible....

•	 Warmer temperatures and a reduction in 

sea ice may upen up areas of the Northwest Passage and the Northern Sea Route 

to transportation. If the Northwest Passage becomes ice-free for summer travel, 

an increase in visitation to the Arctic via 

cruise ship is expected (ACIA 2004). 

•	 Damage to roads, buildings, and other 

infrastructure is predicted with climate 

change, due largely to permafrost thawing 

(ACIA 2004; Smith and Levasseur 2003). 

Damage could increase future costs for 

Alaska’s public infrastructure from 3.6 to 

6.1 billion dollars (10% to 20%) by 2030 

to 5.6 to 7.6 billion dollars (10% to 12%) 

by 2080 (Larsen et al. 2007b). 

•	The majority of Alaskans polled believe 

that tourism will increase as a result of 

global climate change (Leiserowitz and 

Craciun 2006).

A visitor hikes the Alaska 

Coastal Plain; USFWS photo.

Temperature Water Cycle Vegetation Wildlife Disturbance Cultural Resources Visitor Experience
18 Climate Change Talking Points NPS/FWS—2010

III. No Regrets Actions: How Individuals, Parks, Refuges, and 

Their Partners Can Do Their Part

Individuals, businesses, and agencies release carbon dioxide (CO2), the principal greenhouse gas, through burning of fossil 

fuels for electricity, heating, transportation, food production, and other day-to-day activities. Increasing levels of atmospheric 

CO2 have measurably increased global average temperatures, and are projected to cause further changes in global climate, with 

severe implications for vegetation, wildlife, oceans, water resources, and human populations. Emissions reduction – limiting 

production of CO2 and other greenhouse gases - is an important step in addressing climate change. It is the responsibility of 

agencies and individuals to find ways to reduce greenhouse gas emissions and to educate about the causes and consequences 

of climate change, and ways in which we can reduce our impacts on natural resources. There are many simple actions that each 

of us can take to reduce our daily carbon emissions, some of which will even save money.

Agencies Can...

Improve sustainability and 

energy efficiency

•	 Use energy efficient products, such as 

ENERGY STAR® approved office equipment, appliances and light bulbs.

•	 Initiate an energy efficiency program to 

monitor energy use in buildings. Provide 

guidelines for reducing energy consumption.

•	 Convert to renewable energy sources 

such as solar or wind generated power.

•	 Specify “green” designs for construction 

of new or remodeled buildings.

•	 Include discussions of climate change in 

park Environmental Management System. 

•	 Conduct an emissions inventory and set 

goals for CO2 reduction.

•	 Provide alternative transportation options such as employee bicycles and shuttles for within-unit commuting. 

•	 Provide hybrid electric or propane-fueled 

vehicles for official use, and impose fuel 

standards for park vehicles. Reduce the 

number and/or size of park vehicles and 

boats to maximize efficiency.

•	 Provide a shuttle service or another form 

of alternate transportation for visitor and 

employee travel to and within the unit. 

•	 Provide incentives for use of alternative 

transportation methods.

•	 Use teleconferences and webinars or other 

forms of modern technology in place of 

travel to conferences and meetings.

Implement Management Actions

•	 Engage and enlist collaborator support 

(e.g., tribes, nearby agencies, private landholders) in climate change discussions, responses, and mitigation. 

•	 Develop strategies and identify priorities 

for managing uncertainty surrounding climate change effects in parks and refuges. 

•	 Build a strong partnership-based foundation for future conservation efforts.

•	 Identify strategic priorities for climate 

change efforts when working with partners.

•	 Incorporate anticipated climate change 

impacts, such as decreases in lake levels, 

rising sea levels, or changes in vegetation 

and wildlife, into management plans.

•	 Encourage research and scientific study in 

park units and refuges.

•	 Design long-term monitoring projects and 

management activities that do not rely 

An interpretive brochure about 

climate change impacts to National Parks was created in 2006 

and was distributed widely. This 

brochure was updated in 2008.
National Park Service 19

solely on fossil fuel-based transportation 

and infrastructure.

•	 Incorporate products and services that address climate change in the development 

of all interpretive and management plans. 

•	 Take inventory of the facilities/boundaries/species within your park or refuge 

that may benefit from or be vulnerable to 

climate change mitigation or adaptation 

activities.

•	 Participate in gateway community sustainability efforts.

•	 Recognize the value of ecosystem services 

that an area can provide, and manage the 

area to sustain these services. Conservation is more cost-effective than restoration 

and helps maintain ecosystem integrity.

•	 Provide recycling options for solid waste 

and trash generated within the park.

•	 Anticipate potential landscape and sealevel changes when designing new or replacement facilities and infrastructure, including positioning new facilities to avoid 

or mitigate impact from sea level rise or 

permafrost thawing.

•	 Work with native communities to identify 

climate refugia as special places for sustaining traditional subsistence living.

Restore damaged landscapes

•	 Restoration efforts are important as a 

means for enhancing species’ ability to 

cope with stresses and adapt to climatic 

and environmental changes. Through restoration of natural areas, we can lessen climate change impacts on species and their 

habitats. These efforts will help preserve 

biodiversity, natural resources, and recreational opportunities.

•	 Strategically focus restoration efforts, both 

in terms of the types of restoration undertaken and their national, regional, and 

local scale and focus, to help maximize 

resilience.

•	 Restore and conserve connectivity within 

habitats, protect and enhance instream 

flows for fish, and maintain and develop 

access corridors to climate change refugia. 

Educate staff and the public

•	 Post climate change information in easily accessible locations such as on bulletin 

boards and websites.

•	 Provide training for park and refuge employees and partners on effects of climate 

change on resources, and on dissemination of climate change knowledge to the 

public.

•	 Support the development of region, park, 

or refuge-specific interpretive products on 

the impacts of climate change. 

•	 Incorporate climate change research and 

information in interpretive and education 

outreach programming.

•	 Distribute up-to-date interpretive products (e.g., the National Park Service-wide 

Climate Change in National Parks brochure).

•	 Develop climate change presentations for 

local civic organizations, user and partner 

conferences, national meetings, etc.

•	 Incorporate climate change questions and 

answers into Junior Ranger programs.

Park Service employees install 

solar panels at San Francisco 

Maritime National Historical 

Park (Top); At the National Mall, 

Park Service employees use 

clean-energy transportation to 

lead tours; NPS photos. 
20 Climate Change Talking Points NPS/FWS—2010

The Climate Friendly Parks 

Program is a joint partnership 

between the U.S. Environmental Protection Agency and the 

National Park Service. Climate 

Friendly Parks from around the 

country are leading the way in 

the effort to protect our parks’ 

natural and cultural resources 

and ensure their preservation 

for future generations; NPS image. 

•	 Help visitors make the connection between reducing greenhouse gas emissions 

and resource stewardship.

•	 Encourage visitors to use public or nonmotorized transportation to and around 

parks.

•	 Encourage visitors to reduce their carbon 

footprint in their daily lives and as part of 

their tourism experience.

Individuals can...

•	 In the park or refuge park their car and 

walk or bike. Use shuttles where available. 

Recycle and use refillable water bottles. 

Stay on marked trails to help further ecosystem restoration efforts.

•	 At home, walk, carpool, bike or use public transportation if possible. A full bus 

equates to 40 fewer cars on the road. 

When driving, use a fuel-efficient vehicle.

•	 Do not let cars idle - letting a car idle for 

just 20 seconds burns more gasoline than 

turning it off and on again.

•	 Replace incandescent bulbs in the five 

most frequently used light fixtures in the 

home with bulbs that have the ENERGY 

STAR® rating. If every household in the 

U.S. takes this one simple action we will 

prevent greenhouse gas emissions equivalent to the emissions from nearly 10 million cars, in addition to saving money on 

energy costs.

Reduce, Reuse, Recycle, Refuse

•	 Use products made from recycled paper, 

plastics and aluminum - these use 55-95% 

less energy than products made from 

scratch. 

•	 Purchase a travel coffee mug and a reusable water bottle to reduce use of disposable products (Starbucks uses more than 1 

billion paper cups a year). 

•	 Carry reusable bags instead of using paper 

or plastic bags. 

•	 Recycle drink containers, paper, newspapers, electronics, and other materials. Bring recyclables home for proper 

disposal when recycle bins are not available. Rather than taking old furniture and 

clothes to the dump, consider “recycling” 

them at a thrift store. 

•	 Keep an energy efficient home. Purchase 

ENERGY STAR® appliances, properly 

insulate windows, doors and attics, and 

lower the thermostat in the winter and 

raise it in the summer (even 1-2 degrees 

makes a big difference). Switch to green 

power generated from renewable energy 

sources such as wind, solar, or geothermal.

•	 Buy local goods and services that minimize 

emissions associated with transportation.

•	 Encourage others to participate in the actions listed above.

For more information on how you can reduce carbon emissions and engage in climatefriendly activities, check out these websites:

EPA- What you can do: http://www.epa.gov/

climatechange/wycd/index.html

NPS- Do Your Part! Program: http://www.

nps.gov/climatefriendlyparks/doyourpart.

html

US Forest Service Climate Change Program: 

http://www.fs.fed.us/climatechange/

United States Global Change Research Program: http://www.globalchange.gov/

U.S. Fish and Wildlife Service Climate change: 

http://www.fws.gov/home/climatechange/

“Humankind has not 

woven the web of life. 

We are but one thread 

within it. Whatever we 

do to the web, we do 

to ourselves. All things 

are bound together. 

All things connect.”

 —Chief Seattle
National Park Service 21

IV. Global Climate Change

The IPCC is a scientific intergovernmental, international body established by the World Meteorological Organization (WMO) 

and by the United Nations Environment Programme (UNEP). The information the IPCC provides in its reports is based on 

scientific evidence and reflects existing consensus viewpoints within the scientific community. The comprehensiveness of the 

scientific content is achieved through contributions from experts in all regions of the world and all relevant disciplines including, where appropriately documented, industry literature and traditional practices, and a two stage review process by experts 

and governments.

Definition of climate change: The IPCC defines climate change as a change in the state of the climate that can be identified (e.g. 

using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, 

typically decades or longer. All statements in this section are synthesized from the IPCC report unless otherwise noted.

A. Temperature and 

Greenhouse Gases

What scientists know...

•	 Warming of the Earth’s climate system is 

unequivocal, as evidenced from increased 

air and ocean temperatures, widespread 

melting of snow and ice, and rising global 

average sea level (Figure 1).

•	 In the last 100 years, global average surface 

temperature has risen about 0.74°C over 

the previous 100-year period, and the rate 

of warming has doubled from the previous 

century. Eleven of the 12 warmest years in 

the instrumental record of global surface 

temperature since 1850 have occurred 

since 1995 (Figure 1).

•	 Although most regions over the globe have 

experienced warming, there are regional 

variations: land regions have warmed faster than oceans and high northern latitudes 

have warmed faster than the tropics. Average Arctic temperatures have increased 

at almost twice the global rate in the past 

100 years, primarily because loss of snow 

and ice results in a positive feedback via 

increased absorption of sunlight by ocean 

waters (Figure 2).

•	 Over the past 50 years widespread changes 

in extreme temperatures have been observed, including a decrease in cold days 

and nights and an increase in the frequency of hot days, hot nights, and heat waves.

•	 Winter temperatures are increasing more 

rapidly than summer temperatures, particularly in the northern hemisphere, and 

Figure 1. Observed changes in (a) global average surface temperature; (b) 

global average sea level from tide gauge (blue) and satellite (red) data and (c) 

Northern Hemisphere snow cover for March-April. All differences are relative 

to corresponding averages for the period 1961-1990. Smoothed curves represent decadal averaged values while circles show yearly values. The shaded 

areas are the uncertainty intervals estimated from a comprehensive analysis of 

known uncertainties (a and b) and from the time series (c) (IPCC 2007a).
22 Climate Change Talking Points NPS/FWS—2010

there has been an increase in the length 

of the frost-free period in mid- and highlatitude regions of both hemispheres.

•	 Climate change is caused by alterations in 

the energy balance within the atmosphere 

and at the Earth’s surface. Factors that 

affect Earth’s energy balance are the atmospheric concentrations of greenhouse 

gases and aerosols, land surface properties, 

and solar radiation. 

•	 Global atmospheric concentrations of 

greenhouse gases have increased significantly since 1750 as the result of human 

activities. The principal greenhouse gases 

are carbon dioxide (CO2), primarily from 

fossil fuel use and land-use change; methane (CH4) and nitrous oxide (N2O), primarily from agriculture; and halocarbons 

(a group of gases containing fluorine, chlorine or bromine), principally engineered 

chemicals that do not occur naturally.

•	 Direct measurements of gases trapped in 

ice cores demonstrate that current CO2 

and CH4 concentrations far exceed the 

natural range over the last 650,000 years 

and have increased markedly (35% and 

148% respectively), since the beginning of 

the industrial era in 1750.

•	 Both past and future anthropogenic CO2 

emissions will continue to contribute to 

warming and sea level rise for more than 

a millennium, due to the time scales required for the removal of the gas from the 

atmosphere. 

Figure 2. Comparison of observed continental- and globalscale changes in surface temperature with results simulated 

by climate models using either 

natural or both natural and anthropogenic forcings. Decadal 

averages of observations are 

shown for the period 1906-2005 

(black line) plotted against the 

centre of the decade and relative to the corresponding average for the period 1901-1950. 

Lines are dashed where spatial 

coverage is less than 50%. Blue 

shaded bands show the 5 to 

95% range for 19 simulations 

from five climate models using 

only the natural forcings due 

to solar activity and volcanoes. 

Red shaded bands show the 5 

to 95% range for 58 simulations 

from 14 climate models using 

both natural and anthropogenic 

forcings (IPCC 2007a).
National Park Service 23

•	 Warming temperatures reduce oceanic uptake of atmospheric CO2, increasing the 

fraction of anthropogenic emissions remaining in the atmosphere. This positive 

carbon cycle feedback results in increasingly greater accumulation of atmospheric 

CO2 and subsequently greater warming 

trends than would otherwise be present in 

the absence of a feedback relationship.

•	 There is very high confidence that the 

global average net effect of human activities since 1750 has been one of warming.

•	 Scientific evidence shows that major and 

widespread climate changes have occurred with startling speed. For example, 

roughly half the north Atlantic warming 

during the last 20,000 years was achieved 

in only a decade, and it was accompanied 

by significant climatic changes across most 

of the globe (NRC 2008).

What scientists think is likely...

•	 Anthropogenic warming over the last 

three decades has likely had a discernible 

influence at the global scale on observed 

changes in many physical and biological 

systems. 

•	 Average temperatures in the Northern 

Hemisphere during the second half of the 

20th century were very likely higher than 

during any other 50-year period in the last 

500 years and likely the highest in at least 

the past 1300 years. 

•	 Most of the warming that has occurred 

since the mid-20th century is very likely 

due to increases in anthropogenic greenhouse gas concentrations. Furthermore, 

it is extremely likely that global changes 

observed in the past 50 years can only be 

explained with external (anthropogenic) 

forcings (influences) (Figure 2). 

•	 There is much evidence and scientific consensus that greenhouse gas emissions will 

continue to grow under current climate 

change mitigation policies and development practices. For the next two decades 

a warming of about 0.2oC per decade is 

projected for a range of emissions scenarios; afterwards, temperature projections 

increasingly depend on specific emissions 

scenarios (Table 1). 

•	 It is very likely that continued greenhouse 

gas emissions at or above the current rate 

will cause further warming and result in 

changes in the global climate system that 

will be larger than those observed during 

the 20th century.

•	 It is very likely that hot extremes, heat 

waves and heavy precipitation events will 

become more frequent. As with current 

trends, warming is expected to be greatest 

over land and at most high northern latitudes, and least over the Southern Ocean 

(near Antarctica) and the northern North 

Atlantic Ocean.

What scientists think is possible...

•	 Global temperatures are projected to increase in the future, and the magnitude of 

temperature change depends on specific 

emissions scenarios, and ranges from a 

1.1oC to 6.4oC increase by 2100 (Table 1). 

Table 1. Projected global average surface warming at the 

end of the 21st century, adapted 

from (IPCC 2007b).

Notes: a) Temperatures are 

assessed best estimates and 

likely uncertainty ranges 

from a hierarchy of models of 

varying complexity as well as 

observational constraints. b) 

Temperature changes are expressed as the difference from 

the period 1980-1999. To express the change relative to the 

period 1850-1899 add 0.5°C. c) 

Year 2000 constant composition 

is derived from AtmosphereOcean General Circulation Models (AOGCMs) only. 

Temperature Change (°C at 2090 – 2099 relative to 

1980 – 1999)a,b

Emissions Scenario Best Estimate Likely Range

Constant Year 2000 

Concentrationsa 0.6 0.3 – 0.9

B1 Scenario 1.8 1.1 – 2.9

B2 Scenario 2.4 1.4 – 3.8

A1B Scenario 2.8 1.7 – 4.4

A2 Scenario 3.4 2.0 – 5.4

A1F1 Scenario 4.0 2.4 – 6.4
24 Climate Change Talking Points NPS/FWS—2010

Figure 3. Sea ice concentrations 

(the amount of ice in a given 

area) simulated by the GFDL 

CM2.1 global coupled climate 

model averaged over August, 

September and October (the 

months when Arctic sea ice concentrations generally are at a 

minimum). Three years (1885, 

1985 & 2085) are shown to illustrate the model-simulated 

trend. A dramatic reduction of 

summertime sea ice is projected, 

with the rate of decrease being 

greatest during the 21st century 

portion. The colors range from 

dark blue (ice free) to white 

(100% sea ice covered); Image 

courtesy of NOAA GFDL.

•	 Anthropogenic warming could lead to 

changes in the global system that are 

abrupt and irreversible, depending on the 

rate and magnitude of climate change.

•	 Roughly 20-30% of species around the 

globe could become extinct if global average temperatures increase by 2 to 3oC over 

pre-industrial levels.

B. Water, Snow, and Ice

What scientists know...

•	 Many natural systems are already being affected by increased temperatures, particularly those related to snow, ice, and frozen 

ground. Examples are decreases in snow 

and ice extent, especially of mountain glaciers; enlargement and increased numbers 

of glacial lakes; decreased permafrost extent; increasing ground instability in permafrost regions and rock avalanches in 

mountain regions; and thinner sea ice and 

shorter freezing seasons of lake and river 

ice (Figure 3).

•	 Annual average Arctic sea ice extent has 

shrunk by 2.7% per decade since 1978, and 

the summer ice extent has decreased by 

7.4% per decade. Sea ice extent during the 

2007 melt season plummeted to the lowest 

levels since satellite measurements began 

in 1979, and at the end of the melt season 

September 2007 sea ice was 39% below 

the long-term (1979-2000) average (NSIDC 

2008)(Figure 4).

•	 Global average sea level rose at an average 

rate of 1.8 mm per year from 1961 to 2003 

and at an average rate of 3.1 mm per year 

from 1993 to 2003. Increases in sea level 

since 1993 are the result of the following 

contributions: thermal expansion, 57%; 

melting glaciers and ice caps, 28%, melting 

polar ice sheets, 15%. 

•	 The CO2 content of the oceans increased 

by 118 ± 19 Gt (1 Gt = 109 tons) between 

A.D. 1750 (the end of the pre-industrial 

period) and 1994 as the result of uptake 

of anthropogenic CO2 emissions from the 

atmosphere, and continues to increase 

by about 2 Gt each year (Sabine et al. 

2004; Hoegh-Guldberg et al. 2007). This 

Figure 4. Arctic sea ice in September 2007 (blue line) is far below the previous low 

record year of 2005 (dashed line), and was 39% below where we would expect to be 

in an average year (solid gray line). Average September sea ice extent from 1979 to 

2000 was 7.04 million square kilometers. The climatological minimum from 1979 to 

2000 was 6.74 million square kilometers (NSIDC 2008).
National Park Service 25

increase in oceanic CO2 has resulted in 

a 30% increase in acidity (a decrease in 

surface ocean pH by an average of 0.1 

units), with observed and potential severe 

negative consequences for marine organisms and coral reef formations (Orr et al. 

2005: McNeil and Matear 2007; Riebesell 

et al. 2009).

•	 Oceans are noisier due to ocean acidification reducing the ability of seawater 

to absorb low frequency sounds (noise 

from ship traffic and military activities). 

Low-frequency sound absorption has decreased over 10% in both the Pacific and 

Atlantic over the past 200 years. An assumed additional pH drop of 0.3 (due 

to anthropogenic CO2 emissions) accompanied with warming will lead to sound 

absorption below 1 kHz being reduced by 

almost half of current values (Hester et. al. 

2008).

•	 Even if greenhouse gas concentrations are 

stabilized at current levels thermal expansion of ocean waters (and resulting sea 

level rise) will continue for many centuries, 

due to the time required to transport heat 

into the deep ocean.

•	 Observations since 1961 show that the 

average global ocean temperature has increased to depths of at least 3000 meters, 

and that the ocean has been taking up 

over 80% of the heat added to the climate 

system.

•	 Hydrologic effects of climate change include increased runoff and earlier spring 

peak discharge in many glacier- and snowfed rivers, and warming of lakes and rivers. 

•	 Runoff is projected to increase by 10 to 

40% by mid-century at higher latitudes 

and in some wet tropical areas, and to decrease by 10 to 30% over some dry regions 

at mid-latitudes and dry tropics. Areas in 

which runoff is projected to decline face a 

reduction in the value of the services provided by water resources. 

•	 Precipitation increased significantly from 

1900 to 2005 in eastern parts of North 

and South America, northern Europe, and 

northern and central Asia. Conversely, 

precipitation declined in the Sahel, the 

Mediterranean, southern Africa, and parts 

of southern Asia (Figure 5).

What scientists think is likely....

•	 Widespread mass losses from glaciers and 

reductions in snow cover are projected 

to accelerate throughout the 21st century, 

reducing water availability and changing 

seasonality of flow patterns.

•	 Model projections include contraction of 

snow cover area, widespread increases 

in depth to frost in permafrost areas, and 

Arctic and Antarctic sea ice shrinkage.

•	 The incidence of extreme high sea level 

has likely increased at a broad range of 

sites worldwide since 1975. 

•	 Based on current model simulations it is 

very likely that the meridional overturning 

circulation (MOC) of the Atlantic Ocean 

will slow down during the 21st century; 

nevertheless regional temperatures are 

predicted to increase. Large-scale and persistent changes in the MOC may result in 

changes in marine ecosystem productivity, 

Figure 5. Relative changes in 

precipitation (in percent) for 

the period 2090-2099, relative 

to 1980-1999. Values are multimodel averages based on the 

SRES A1B scenario for December 

to February (left) and June to 

August (right). White areas are 

where less than 66% of the 

models agree in the sign of the 

change and stippled areas are 

where more than 90% of the 

models agree in the sign of the 

change (IPCC 2007a).

December to February June to August
26 Climate Change Talking Points NPS/FWS—2010

fisheries, ocean CO2 uptake, and terrestrial vegetation.

•	 Globally the area affected by drought has 

likely increased since the 1970s and the 

frequency of extreme precipitation events 

has increased over most areas.

•	 Future tropical cyclones (typhoons and 

hurricanes) are likely to become more 

intense, with larger peak wind speeds and 

increased heavy precipitation. Extra-tropical storm tracks are projected to move 

poleward, with consequent shifts in wind, 

precipitation, and temperature patterns.

•	 Increases in the amount of precipitation 

are very likely in high latitudes and decreases are likely in most subtropical land 

regions, continuing observed patterns 

(Figure 5).

•	 Increases in the frequency of heavy precipitation events in the coming century are 

very likely, resulting in potential damage 

to crops and property, soil erosion, surface and groundwater contamination, and 

increased risk of human death and injury.

What scientists think is possible...

•	 Arctic late-summer sea ice may disappear 

almost entirely by the end of the 21st century (Figure 3).

•	 Current global model studies project that 

the Antarctic ice sheet will remain too cold 

for widespread surface melting and gain 

mass due to increased snowfall. However, 

net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet 

mass balance.

•	 Model-based projections of global average sea level rise at the end of the 21st 

century range from 0.18 to 0.59 meters, 

depending on specific emissions scenarios 

(Table 2). These projections may actually 

underestimate future sea level rise because 

they do not include potential feedbacks or 

full effects of changes in ice sheet flow. 

•	 Partial loss of ice sheets and/or the thermal 

expansion of seawater over very long time 

scales could result in meters of sea level 

rise, major changes in coastlines and inundation of low-lying areas, with greatest 

effects in river deltas and low-lying islands.

C. Vegetation and Wildlife

What scientists know...

•	 Temperature increases have affected Arctic and Antarctic ecosystems and predator 

species at high levels of the food web.

•	 Changes in water temperature, salinity, 

oxygen levels, circulation, and ice cover 

in marine and freshwater ecosystems have 

resulted in shifts in ranges and changes 

in algal, plankton, and fish abundance in 

high-latitude oceans; increases in algal and 

zooplankton abundance in high-latitude 

and high-altitude lakes; and range shifts 

and earlier fish migrations in rivers. 

•	 High-latitude (cooler) ocean waters are 

currently acidified enough to start dissolving pteropods; open water marine snails 

Table 2. Projected global average sea level rise at the end of 

the 21st century, adapted from 

IPCC 2007b.

Notes: a) Temperatures are assessed best estimates and likely 

uncertainty ranges from a hierarchy of models of varying complexity as well as observational 

constraints.

Emissions Scenario

Sea level rise 

(m at 2090 – 2099 relative to 1980 – 1999)

Model-based range (excluding future rapid 

dynamical changes in ice flow)

Constant Year 2000 

Concentrationsa 0.3 – 0.9

B1 Scenario 1.1 – 2.9

B2 Scenario 1.4 – 3.8

A1B Scenario 1.7 – 4.4

A2 Scenario 2.0 – 5.4

A1F1 Scenario 2.4 – 6.4
National Park Service 27

which are one of the primary food sources 

of young salmon and mackerel (Fabry et al. 

2008, Feely et al. 2008). In lower latitude 

(warmer) waters, by the end of this century Humboldt squid’s metabolic rate will 

be reduced by 31% and activity levels by 

45% due to reduced pH, leading to squid 

retreating at night to shallower waters to 

feed and replenish oxygen levels (Rosa 

and Seibel 2008). 

•	 A meta-analysis of climate change effects 

on range boundaries in Northern Hemisphere species of birds, butterflies, and 

alpine herbs shows an average shift of 6.1 

kilometers per decade northward (or 6.1 

meters per decade upward), and a mean 

shift toward earlier onset of spring events 

(frog breeding, bird nesting, first flowering, 

tree budburst, and arrival of migrant butterflies and birds) of 2.3 days per decade 

(Parmesan and Yohe 2003).

•	 Poleward range shifts of individual species 

and expansions of warm-adapted communities have been documented on all continents and in most of the major oceans of 

the world (Parmesan 2006).

•	 Satellite observations since 1980 indicate 

a trend in many regions toward earlier 

greening of vegetation in the spring linked 

to longer thermal growing seasons resulting from recent warming.

•	 Over the past 50 years humans have 

changed ecosystems more rapidly and extensively than in any previous period of 

human history, primarily as the result of 

growing demands for food, fresh water, 

timber, fiber, and fuel. This has resulted in 

a substantial and largely irreversible loss of 

Earth’s biodiversity 

•	 Although the relationships have not been 

quantified, it is known that loss of intact ecosystems results in a reduction in 

ecosystem services (clean water, carbon 

sequestration, waste decomposition, crop 

pollination, etc.).

What scientists think is likely...

•	 The resilience of many ecosystems is likely 

to be exceeded this century by an unprecedented combination of climate change, 

associated disturbance (flooding, drought, 

wildfire, insects, ocean acidification) and 

other global change drivers (land use 

change, pollution, habitat fragmentation, 

invasive species, resource over-exploitation) (Figure 6). 

•	 Exceedance of ecosystem resilience may 

be characterized by threshold-type responses such as extinctions, disruption of 

ecological interactions, and major changes 

in ecosystem structure and disturbance 

regimes.

•	 Net carbon uptake by terrestrial ecosystems is likely to peak before mid-century 

and then weaken or reverse, amplifying 

climate changes. By 2100 the terrestrial 

biosphere is likely to become a carbon 

source.

•	 Increases in global average temperature 

above 1.5 to 2.5°C and concurrent atmospheric CO2 concentrations are projected 

to result in major changes in ecosystem 

structure and function, species’ ecological interactions, and species’ geographical 

ranges. Negative consequences are projected for species biodiversity and ecosystem goods and services.

•	 Model projections for increased atmospheric CO2 concentration and global 

temperatures significantly exceed values 

for at least the past 420,000 years, the 

period during which more extant marine 

organisms evolved. Under expected 21st

century conditions it is likely that global 

warming and ocean acidification will compromise carbonate accretion, resulting in 

less diverse reef communities and failure 

of some existing carbonate reef structures. 

Climate changes will likely exacerbate local stresses from declining water quality and overexploitation of key species 

(Hoegh-Guldberg et al. 2007).

•	 Ecosystems likely to be significantly impacted by changing climatic conditions 

include:

i. Terrestrial – tundra, boreal forest, and 

mountain regions (sensitivity to warming); Mediterranean-type ecosystems 

and tropical rainforests (decreased 

rainfall)
28 Climate Change Talking Points NPS/FWS—2010

Figure 6. Examples of impacts associated with projected global average surface warming. Upper panel: Illustrative examples of global 

impacts projected for climate changes (and sea level and atmospheric CO2 where relevant) associated with different amounts of increase 

in global average surface temperature in the 21st century. The black lines link impacts; broken-line arrows indicate impacts continuing with 

increasing temperature. Entries are placed so that the left-hand side of text indicates the approximate level of warming that is associated 

with the onset of a given impact. Quantitative entries for water scarcity and flooding represent the additional impacts of climate change 

relative to the conditions projected across the range of SRES scenarios A1FI, A2, B1 and B2. Adaptation to climate change is not included 

in these estimations. Confidence levels for all statements are high. Lower panel: Dots and bars indicate the best estimate and likely ranges 

of warming assessed for the six SRES marker scenarios for 2090-2099 relative to 1980-1999 (IPCC 2007a).
National Park Service 29

ii. Coastal – mangroves and salt marshes 

(multiple stresses) 

iii. Marine – coral reefs (multiple stresses); 

sea-ice biomes (sensitivity to warming)

What scientists think is possible...

•	 Approximately 20% to 30% of plant and 

animal species assessed to date are at increased risk of extinction with increases in 

global average temperature in excess of 1.5 

to 2.5°C.

•	 Endemic species may be more vulnerable 

to climate changes, and therefore at higher 

risk for extinction, because they may have 

evolved in locations where paleo-climatic 

conditions have been stable.

•	 Although there is great uncertainty about 

how forests will respond to changing 

climate and increasing levels of atmospheric CO2, the factors that are most 

typically predicted to influence forests 

are increased fire, increased drought, and 

greater vulnerability to insects and disease 

(Brown 2008).

•	 If atmospheric CO2 levels reach 450 ppm 

(projected to occur by 2030–2040 at the 

current emissions rates), reefs may experience rapid and terminal decline worldwide from multiple climate change-related 

direct and indirect effects including mass 

bleaching, ocean acidification, damage to 

shallow reef communities,reduction of 

biodiversity, and extinctions. (Veron et al. 

2009). At atmospheric CO2 levels of 560 

ppmv, calcification of tropical corals is expected to decline by 30%, and loss of coral 

structure in areas of high erosion may 

outpace coral growth. With unabated CO2 

emissions, 70% of the presently known 

reef locations (including cold-water corals) will be in corrosive waters by the end 

of this century (Riebesell, et al. 2009).

D. Disturbance

What scientists know...

•	 Climate change currently contributes to 

the global burden of disease and premature death through exposure to extreme 

events and changes in water and air quality, food quality and quantity, ecosystems, 

agriculture, and economy (Parry et al. 

2007).

•	 The most vulnerable industries, settlements, and societies are generally those 

in coastal and river flood plains, those 

whose economies are closely linked with 

climate-sensitive resources, and those in 

areas prone to extreme weather events. 

•	 By 2080-2090 millions more people than 

today are projected to experience flooding 

due to sea level rise, especially those in the 

low-lying megadeltas of Asia and Africa 

and on small islands.

•	 Climate change affects the function and 

operation of existing water infrastructure 

and water management practices, aggravating the impacts of population growth, 

changing economic activity, land-use 

change, and urbanization.

What scientists think is likely...

•	 Up to 20% of the world’s population will 

live in areas where river flood potential 

could increase by 2080-2090, with major 

consequences for human health, physical 

infrastructure, water quality, and resource 

availability.

•	 The health status of millions of people is 

projected to be affected by climate change, 

through increases in malnutrition; increased deaths, disease, and injury due to 

extreme weather events; increased burden 

of diarrheal diseases; increased cardiorespiratory disease due to higher concentrations of ground-level ozone in urban 

areas; and altered spatial distribution of 

vector-borne diseases.

•	 Risk of hunger is projected to increase at 

lower latitudes, especially in seasonally 

dry and tropical regions.

What scientists think is possible...

•	 Although many diseases are projected to 

increase in scope and incidence as the 

result of climate changes, lack of appropriate longitudinal data on climate changerelated health impacts precludes definitive 

assessment.
30 Climate Change Talking Points NPS/FWS—2010

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National Park Service 39
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides 

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