** rnA United States	AuOUSt 2016
agsigW §"|^[OL Environmental Protection
#1 Agency	EPA 430"F-16"004
What Climate Change
Means for Alaska

Alaska's climate is changing. Over the past 60 years,
most of the state has warmed three degrees (F) on
average and six degrees during winter. As a result, Arctic
sea ice is retreating, shores are eroding, glaciers are
shrinking, permafrost is thawing, and insect outbreaks
and wildfires are becoming more common. In the coming
decades, these effects are likely to accelerate.
Our climate is changing because the earth is warming.
People have increased the amount of carbon dioxide in
the air by 40 percent since the late 1700s. Other heat-
trapping greenhouse gases are also increasing. These
gases have warmed the surface and lower atmosphere
of our planet about one degree during the last 50 years.
Evaporation increases as the atmosphere warms, which
increases humidity, average rainfall, and the frequency
of heavy rainstorms in many places—but contributes to
drought in others.
Greenhouse gases are also changing the world's oceans
and ice cover. Carbon dioxide reacts with water to
form carbonic acid, so the oceans are becoming more
acidic. The surface of the ocean has warmed about one
degree during the last 80 years. Warming is causing
snow to melt earlier in spring, and mountain glaciers
are retreating. Even the great ice sheets on Greenland
and Antarctica are shrinking. Thus the sea is rising at an
increasing rate.
Temperature change ( F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 B.5
Rising temperatures in the last century. Alaska has warmed
more than most of the United States. Source: EPA, Climate
Change Indicators in the United States.
Sea ice provides habitat for polar bears, walruses, and other animals;
hunting grounds for Alaska Native communities; and a buffer against storm
damage. But all of that is threatened by rising temperatures.

Permafrost, Infrastructure, and Energy Production
Permafrost soil lies beneath about 80 percent of Alaska's land
surface. Much of this land could shift or sink if rising temperatures
thaw the permafrost. That can damage pipelines, buildings, roads
and other transportation infrastructure, water supplies, and sewer
systems. Thawing permafrost is likely to increase the cost of
maintaining public infrastructure by 10 to 20 percent in the next
20 years.
Energy production depends on vehicles that must drive on frozen
tundra and ice roadways to support oil and gas exploration activities
in areas without conventional highways. Because of melting, the
travel season has shrunk from more than 200 days in 1970 to
around 100 days in 2002. Energy production and transportation
could benefit from warming in other ways, though. For example,
less sea ice could allow more ship travel and oil and gas exploration
in the Arctic Ocean.
Fisheries and Wildlife
Increasing ocean acidity threatens fishing, which is Alaska's third
largest industry and a key source of food for many native commu -
nities. Higher acidity harms shellfish and certain types of plankton
that depend on minerals in the water to build their skeletons and
shells. Less plankton means less food available to support popula-
tions of salmon and other fish.
Climate change is likely to affect Alaska's animal biodiversity.
Declining Arctic sea ice can harm polar bear populations, by
reducing their ability to hunting seals. Polar bear, walrus, and seal
populations are expected to decline further, due to loss of snow
and ice cover—especially walrus, which bear and nurse their
calves on summer sea ice. Higher evaporation, permafrost thaw,
and other factors have decreased the area of lakes in the past half-
century, particularly in southern Alaska. Continued loss of lake and
wetland areas in Alaska is likely to reduce habitat for the millions
of migratory birds that rely on these areas for breeding.
Forests and Tundra
Rising temperatures in interior Alaska have increased the length of
the growing season by 45 percent during the last century, and the
growing season will continue to lengthen. While a longer growing
season could boost agriculture and plant growth, other changes
could harm Alaska's forest and tundra plants. Wetland drying;
warmer, drier summers; and more frequent thunderstorms have
led to more large forest and tundra fires in the last 10 years than in
any decade since recordkeeping began in the 1940s. The number
of acres burned each year is likely to double by 2050 and triple
by 2100.
In south-central Alaska,
during the 1990s, milder
winters and warmer
temperatures increased
the winter survival of the
spruce bark beetle and
allowed it to complete
its life cycle in one year
instead of the normal
two years. Nine years of
drought stress weakened
spruce trees' normal
defense mechanisms
against the beetles. This
combination of ecological factors—all related to climate change—
led to the largest reported outbreak of spruce bark beetles in the
world, which killed many trees.
Alaska Native Communities
Many of Alaska's native communities are vulnerable to climate
change, because their travel, hunting, food, and infrastructure
depend on a landscape that is frozen for at least part of the year.
The loss of sea ice restricts the subsistence lifestyle of groups such
as the Yup'ik, Inupiat, and Inuit by limiting hunting grounds and
reducing habitat for traditional food sources such as walrus. Erosion
and thawing permafrost are forcing some coastal communities
to consider relocating to more stable land. Jobs in the general
economy are scarce in these villages, so threats to the resources on
which Alaska Natives rely make them particularly vulnerable to the
impacts of climate change.
Health and Vulnerable People
Climate change is likely to amplify some threats to health in Alaska.
Certain people are especially vulnerable, including children, the
elderly, the sick, and the poor.
"Drunken forests" occur when the perma-
frost under trees thaws, causing them to
lean. Credit: NOAA,
The sources of information about climate and the impacts of climate change in this publication are: the national climate assessments by the U.S. Global Change Research
Program, synthesis and assessment products by the U.S. Climate Change Science Program, assessment reports by the Intergovernmental Panel on Climate Change, and EPA's
Climate Change Indicators in the United States. Mention of a particular season, location, species, or any other aspect of an impact does not imply anything about the likelihood or
importance of aspects that are not mentioned. For more information about climate change science, impacts, responses, and what you can do, visit EPA's Climate Change website
at www.epa.aov/climatechanae.