# Impacts of global warming in Alaska

July 30, 2012, 11:21 am
 Topics: More

The Shoup Glacier in Alaska has been in retreat for most of the last century. Source: Univ. of Alaska

Surface Air Temperature Trends 1942-2003. (Source: Chapman and Walsh, 2004)

More than anywhere else in the United States, Alaska has experienced widespread, adverse impacts from global warming, which are well documented and representative of some of the substantial costs associated with human-caused climate change.

While the earth has warmed approximately 1°F in the last 50 years, according to the National Assessment Synthesis Team, Alaska has warmed approximately 4°F during this same time period. In many ways, Alaska is the “Paul Revere of Global Warming”, and serves as a sentinel for the impacts of global warming. In the Last Frontier these impacts are pervasive and include damage to Alaska’s aquatic systems and wetlands, vegetation, ice, glaciers, permafrost, animals, infrastructure, health, economy, quality of life, and indigenous cultures.

## Water bodies and wetlands

Drying Ponds. (Source: Riordan, et al. 2006)

Water bodies throughout almost all of Alaska are shrinking. In an exhaustive study of closed ponds, scientists have documented a significant loss in the number of ponds in key ecological areas in the last half of the 20th century, including: Copper River Basin (54% loss in number of ponds); Minto Flats (36% loss); Innoko Flats (30% loss).

Similarly, wetlands in studied areas in the Kenai National Wildlife Refuge have decreased by 88% from 1950 to 1996. According to evidence from peat core samples, woody plants are now in areas in the Kenai where there were no trees or shrubs during the last 8,000 to 12,000 years. These and other scientific studies confirm reports of disappearing and shrinking ponds from Alaska Native elders, with many ramifications including adverse impacts on migratory birds.

## Vegetation

White Spruce Response to Warming. (Source: Arctic Climate Impact Assessment (ACIA), 2004)

Forests throughout much of Alaska have been adversely affected by global warming, including white and black spruce, yellow cedar, birch and larch.

According to a study that analyzed thousands of satellite images taken over two decades, there are vast reaches of boreal forest where photosynthesis has decreased over the last 22 years. In central Alaska, where it is dry, white spruce and black spruce have shown documented declines in growth. Projecting forward, a 4°C increase in July temperatures would result in no growth of these species in much of interior Alaska.

Spruce Bark Beetle. (Source: Columbia University and USFS)

Throughout Alaska trees are more vulnerable to increased diseases because of warmer temperatures. For example, south-central Alaska experienced the world’s largest outbreak of spruce bark beetles, killing more than 4 million acres of mature tree stands. Three global warming factors were responsible for this unprecedented outbreak. With longer warmer summers, the spruce bark beetle can complete its life cycle in one year instead of two. Winter temperatures have not been cold enough in two consecutive years to depress survival rates. And finally, the trees have not been able to defend themselves with sufficient pitch because of the stress of heat and drought.

Other serious warming-related diseases that have damaged or killed large numbers of trees include the larch saw fly, spruce bud worm, birch leaf miner, aspen leaf miner, spruce aphid, and birch leaf rollers.

Alaska Acres Burned, 1956-2005. (Source: NOAA National Climate Data Center)

In Southeast Alaska, scientists have documented a massive die-off of yellow cedar on over 500,000 acres of land. Many consider yellow cedar the Tongass National Forest’s most valuable tree both economically and culturally. Because of warmer temperatures, there has been less snow to protect the tree roots and also early dehardening of the foliage. Then, when there is a subsequent late freeze, the foliage and roots are severely injured, leading to tree death.

Vegetation has also been impacted by record breaking fire seasons in Alaska. In 2004, over 6.6 million acres burned, in the largest Alaska fire season ever documented. In 2005, approximately 4.6 million acres of Alaska burned, the third largest area ever recorded. Cumulatively, during these two years, over 25% of the forests in the northeast sector of Alaska perished. These burn rates are entirely consistent with global warming models and predictions. During the last thirty years, the area burned in western North America has doubled, and it is forecast to increase by as much as 80% over the next 100 years under projected climate warming.

## Ice, Glaciers, and Permafrost

Glacier Bay (Riggs Glacier), Alaska. (Source: Matt Nolan)
Melting permafrost causes infrastructure collapse. (Source: Vladimir Romanovsky)

The Arctic Ice Cap is a key ecological component of Alaska’s Beaufort and Chukchi Seas. There was a record low amount of Arctic sea ice in September 2005, and it failed to recover. Between 1979 and 2005, an area twice the size of Texas has melted away, over a 20% decrease in the minimum summer area. In November 2006, ice coverage was the lowest ever recorded for that month. The Bering Sea Ice Sheet is also retreating with documented biological impacts.

The rapid retreat of Alaska’s glaciers represents about 50% of the estimated mass loss by glaciers through 2004 worldwide. Between 1961 and 1998, Alaska and a small part of Canada lost over 588 billion cubic yards of glacial mass. In southeast Alaska, glacier surface elevations decreased over 95% of the area analyzed, with some glaciers thinning in a 52 year period by as much as 640 m (approximately 2,100 feet).

With respect to permafrost, all of the permafrost observatories in Alaska show a substantial warming during the last 20 years, often resulting in damage to infrastructure, rivers, shorelines, lakes, and forests. In locations such as Franklin Bluff on the North Slope, the top layer of permafrost has warmed 3°C between 1987 and 2003. Notably, the warming of permafrost has penetrated deeply, with observations of 2°C warming 60 feet under the ground.

## Animals

Whether on ice, land or water, animals throughout Alaska, have experienced impacts due to global warming.

Polar bears rely on sea ice for their survival, including feeding, mating, and resting. Because of global warming, Alaskan polar bears have experienced less sea ice for their habitat, with subsequent drownings, dislocation from sea ice, cannibalism; starvation, smaller skull size, and higher cub mortality; however, the greater present threat to polar bears Arctic-wide is from overhunting by both indigenous peoples and trophy hunting. Similar ice conditions and trends in the western Hudson Bay population in Canada have resulted in a 22% population decline in 17 years.

Yukon River Warming Temperatures. (Source: Richard Kocan)

In the last fifteen years, the population of Southern Beaufort Sea polar bears has been estimated to be as high as 2,500 bears, and then 1,800 bears. Recently, using the most rigorous surveying methodology yet, the population is believed to be 1,526 bears.

The decrease in sea ice jeopardizes this species. Between 1979 and 1991, 87% of Alaska polar bears surveyed were found mostly on sea ice. This percentage fell to 33% from 1992 to 2004. The impacts include a statistically significant decline in the survival rate for first year polar bear cubs in the southern Beaufort Sea from 0.61 per adult female between 1967-89 to 0.25 per adult female between 1990-2006. Skull measurements of both first year cubs and adult males were also statistically significantly smaller.

In 2006, the World Conservation Union (IUCN) classified polar bears as vulnerable, concluding that five populations of polar bears are declining: southern Beaufort Sea, Western Hudson Bay, Norwegian Bay, Kane Basin, and Baffin Bay. In 2001, they only concluded that one population was declining.

Kenai Streams: Days Above Temperature Standard. (Source: Cook Inlet Keeper, January 2006)

Other Alaska ice dependent species are showing signs of global warming stress, such as walrus and ice seals. As ice pulls away from the continental shelf, the platform used for feeding, there have been observations of abandoned walrus calves. The snow cavities for some ring seals and other ice seals can collapse with warming temperatures, exposing their young to predation or freezing.

Salmon populations, arguably Alaska’s most ecologically and economically significant species, are affected by increased temperatures. Because the Yukon River has warmed over 10°F, up to 45% of Yukon salmon are now infected with the parasite Icthyophonus, never found before 1985. After the warm summer of 2004, the pink salmon harvest in Southeast Alaska was dramatically lower than predicted in 2006. The Alaska Department of Fish and Game (ADF&G) had forecast a purse seine catch of 52 million. According to ADF&G, the actual harvest was only 11.4 million, 40 million less than predicted.

ADF&G also has established standards for salmon habitat water temperatures, concluding that temperatures above 55°F are unhealthy for spawning areas. In four streams monitored in Alaska’s salmon-rich Kenai Peninsula in 2005, each water body exceeded this themperature threshold more than 80 days.

Fish and other species in the Bering Sea, the nation’s fish basket, are also showing signs of stress. The Northern Bering Sea is starting to change from arctic to subarctic conditions caused by warmer air and water temperatures, and less sea ice. Even bottom water temperatures are demonstrably increasing. The prey base of benthic (bottom) feeding walrus, endangered sea ducks like spectacled eiders, and gray whales is declining. Snow crab catches have declined 85% in six years along with other crab decreases; and crab populations have shifted northward. Yellowfin sole and Greenland turbot catches have been dropping, concurrently with declines in fur seals and seabirds. Some pollock are moving into Russian waters because of global warming. Recent surveys have measured the first decrease in U.S. pollock stocks in Alaskan waters in six years, which resulted in reducing the catch allotment. In short, warming waters are creating a northward migration of marine life on an unprecedented scale.

Rapidly retreating glaciers disrupt both fish and birds. Sockeye salmon fry in Skilak Lake showed substantial declines in size in two recent years of large glacial melting. Fry in 2004 were about 50% smaller than average for the prior decade; fry in 2005 were 60% smaller. Similarly, the Kittlitz’s murrelet, which feed at the edge of glaciers, declined 60% between 1991 and 1999 in Glacier Bay and declined 83% since 1976 in Kenai Fjords.

## Infrastructure

Shishmaref, Alaska. (Source: Tony Weyiouanna, Sr.)

Because global warming in Alaska is resulting in accelerated shoreline erosion, melting permafrost and increased flooding, infrastructure is being damaged, and in some cases entire communities must be relocated. Some shorelines have retreated more than 1,500 feet over past few decades. In Western Alaska, the community of Newtok lost 2-3 miles of shore in 40 years. Approximately, 184 communities are at risk from flooding and erosion according to a General Accounting Office estimate.

In 2005, while the nation focused on hurricanes in the Gulf of Mexico, Western Alaska experienced a brutal storm, adversely affecting 34 communities. The storm surge in Nome was nine feet above normal high tides with waves of 12 to 15 feet. Newtok saw 5 to 10 feet of beach disappear along with equipment like a 1,000 gallon fuel tank, and Unalakleet lost 10 to 20 feet of beach.

## Indigenous Cultures

Shishmaref people gathering berries. (Source: Kelly Eningowuk)

Because of their close association with the land, water, vegetation, animals, and weather conditions, Alaska Native cultures are experiencing many consequences of global warming. According to the Arctic Climate Impact Assessment (ACIA), “Climate change is occurring faster than people can adapt. [It] is strongly affecting people in many communities, in some cases threatening their cultural survival.” The ACIA further notes:“…the Arctic is becoming an environment at risk… sea ice is less stable, unusual weather patterns are occurring, vegetation cover is changing, and particular animals are no longer found in traditional hunting areas during specific seasons. Local landscapes, seascapes, and icescapes are becoming unfamiliar, making people feel like strangers in their own land.”

Even artifacts and graves are at risk. For example, indigenous peoples have occupied the region around the coastal village of Point Hope for at least 2,000 years. This area contains some of the richest archaeological resources in Alaska. Because of global warming, the coast is eroding into the sea, permanently washing away precious artifacts and human history. Losing irreplaceable archaeological information is another consequence of global warming.

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