Alaska: America's Cutting Edge Of Climate Change
Alaska has warmed twice as fast as the rest of the nation, bringing widespread impacts
Alaska is the United States’ only Arctic region. Its marine, tundra, boreal (northern) forest, and rain forest ecosystems differ from most of those in other states and are relatively intact. As such, Alaska represents America's cutting edge of climate change, its effects and consequences on human, animal and plant life. Long-term and short-term modeling projects both benefits and crises.
World leaders are now meeting in Paris in what many consider a last-ditch effort to avert the worst consequences of climate change. Climatologists now say that the best case scenario, assuming immediate and dramatic emissions curbs, is that planetary surface temperatures will increase by at least 2 degrees Celsius in the coming decades.
If the nations involved in the Paris talks follow their current trends and don’t reduce greenhouse gas emissions, temperatures could go up by almost 6 degrees Celsius this century. In that scenario, rising temperatures will destroy plant and animal habitats, and reduce yields of important food crops. More people will be exposed to extreme weather events, rising sea level, flooding, wildfires and drought.
The effects of a warming planet are already being felt in Alaska.
The following represents a distillation of a report to the National Climate Assessment written by Patricia Cochran, Alaska Native Science Commission, Henry Huntington, Huntington Consulting, Carl Markon, U.S. Geological Survey, Molly McCammon, Alaska Ocean Observing System, A. David McGuire, U.S. Geological Survey and University of Alaska Fairbanks and Mark Serreze, University of Colorado.
Alaska has warmed twice as fast as the rest of the United States, bringing widespread impacts. Sea ice is rapidly receding and glaciers are shrinking. Thawing permafrost is leading to more wildfire, and affecting infrastructure and wildlife habitat. Rising ocean temperatures and acidification will alter valuable marine fisheries.Rising temperatures have thawed frozen soil in some areas, leaving coastlines vulnerable to storms and tidal activity.
Energy production is the main driver of the state’s economy, providing more than 80% of state government revenue and thousands of jobs. Mining and fishing are the second and third largest industries in the state, with tourism rapidly increasing since the 1990's. Land-based energy exploration will be affected by a shorter season when ice roads are viable, yet reduced sea ice extent may create more opportunity for offshore development.
Alaska has warmed more than twice as rapidly over the past 60 years as the rest of the country, with state-wide average annual air temperature increasing by 3°F and average winter temperature by 6°F, with substantial year-to-year and regional variability. The overall warming has involved more extremely hot days and fewer extremely cold days.
Because of its cold-adapted features and rapid warming, climate change impacts on Alaska are already pronounced, including earlier spring snow melt, reduced sea ice, widespread glacier retreat, warmer permafrost, drier landscapes, and more extensive insect outbreaks and wildfires.
If global emissions continue to increase (A2) during this century, temperatures can be expected to rise 10°F to 12°F in the north, 8°F to 10°F in the interior, and 6°F to 8°F in the rest of the state. Even with substantial emissions reductions (B1), Alaska is projected to warm by 6°F to 8°F in the north and 4°F to 6°F in the rest of the state by the end of the century.
Disappearing Sea Ice
Arctic summer sea ice is receding faster than previously projected and is expected to virtually disappear before mid-century.
This is altering marine ecosystems and leading to greater ship access, offshore development opportunity, and increased community vulnerability to coastal erosion.Reductions in sea ice increase the amount of the sun’s energy that is absorbed by the ocean. This leads to a self-reinforcing climate cycle, because the warmer ocean melts more ice, leaving more dark open water that gains even more heat.
Arctic sea ice extent and thickness have declined substantially, especially in late summer (September), when there is now only about half as much sea ice as at the beginning of the satellite record in 1979. Models that best match historical trends project northern waters that are virtually ice-free by late summer by the 2030's.
With reduced ice extent, the Arctic Ocean is more accessible for marine traffic, including trans-Arctic shipping, oil and gas exploration, and tourism. This facilitates access to the substantial deposits of oil and natural gas under the seafloor in the Beaufort and Chukchi seas, as well as raising the risk to people and ecosystems from oil spills and other drilling and maritime-related accidents.
A seasonally ice-free Arctic Ocean also increases sovereignty and security concerns as a result of potential new international disputes and increased possibilities for marine traffic between the Pacific and Atlantic Oceans.
Most glaciers in Alaska and British Columbia are shrinking substantially.
This trend is expected to continue and has implications for hydro-power production, ocean circulation patterns, fisheries, and global sea level rise.
Alaska is home to some of the largest glaciers and fastest loss of glacier ice on Earth. Loss of glacial volume in Alaska and neighboring British Columbia, Canada, currently contributes 20% to 30% as much surplus freshwater to the oceans as does the Greenland Ice Sheet – about 40 to 70 gigatons per year, comparable to 10% of the annual discharge of the Mississippi River.
Glaciers continue to respond to climate warming for years to decades after warming ceases, so ice loss is expected to continue, even if air temperatures were to remain at current levels. The global decline in glacial and ice-sheet volume is predicted to be one of the largest contributors to global sea level rise during this century.
Glaciers supply about half of the total freshwater input to the Gulf of Alaska. Glacier retreat currently increases river discharge and hydro-power potential in south central and southeast Alaska, but over the longer term might reduce water input to reservoirs and therefore hydro-power resources.
Permafrost temperatures in Alaska are rising, a thawing trend that is expected to continue.
The thawing is causing multiple vulnerabilities through drier landscapes, more wildfire, altered wildlife habitat, increased cost of maintaining infrastructure, and the release of heat-trapping gases that increase climate warming.
Alaska differs from most of the rest of the U.S. in having permafrost – frozen ground that restricts water drainage and therefore strongly influences landscape water balance and the design and maintenance of infrastructure.
In Alaska, 80% of land is underlain by permafrost, and of this, more than 70% is vulnerable to subsidence upon thawing because of ice content that is either variable, moderate, or high. Models project that permafrost in Alaska will continue to thaw, and some models project that near-surface permafrost will be lost entirely from large parts of Alaska by the end of the century.
Changes in terrestrial ecosystems in Alaska and the Arctic may be influencing the global climate system. Permafrost soils throughout the entire Arctic contain almost twice as much carbon as the atmosphere. Warming and thawing of these soils increases the release of carbon dioxide and methane through increased decomposition. Thawing permafrost also delivers organic-rich soils to lake bottoms, where decomposition in the absence of oxygen releases additional methane. Extensive wildfires also release carbon that contributes to climate warming.
This spectrum of changes in Alaskan and other high-latitude terrestrial ecosystems jeopardizes efforts by society to use ecosystem carbon management to offset fossil fuel emissions.
Changing Ocean Temperatures and Chemistry
Current and projected increases in Alaska’s ocean temperatures and changes in ocean chemistry are expected to alter the distribution and productivity of Alaska’s marine fisheries, which lead the U.S. in commercial value.
Ocean acidification, rising ocean temperatures, declining sea ice, and other environmental changes interact to affect the location and abundance of marine fish, including those that are commercially important, those used as food by other species, and those used for subsistence.
Overall habitat extent is expected to change as well, though the degree of the range migration will depend upon the life history of particular species.
The changing temperature and chemistry of the Arctic Ocean and Bering Sea are likely changing their role in global ocean circulation and as carbon sinks for atmospheric CO2 respectively, although the importance of these changes in the global carbon budget remains unresolved.
Ocean waters globally have become 30% more acidic due to absorption of large amounts of human-produced carbon dioxide (CO2) from the atmosphere. This CO2 interacts with ocean water to form carbonic acid that lowers the ocean’s pH (ocean acidification). The polar ocean is particularly prone to acidification because of low temperature and low salt content, the latter resulting from the large freshwater input from melting sea ice and large rivers.
The rising acidity will have particularly strong societal effects on the Bering Sea on Alaska’s west coast because of its high-productivity commercial and subsistence fisheries.
The cumulative effects of climate change in Alaska strongly affect Native communities, which are highly vulnerable to these rapid changes but have a deep cultural history of adapting to change.
With the exception of oil-producing regions in the north, rural Alaska is one of the most extensive areas of poverty in the U.S. in terms of household income, yet residents pay the highest prices for food and fuel. Major food sources are under stress due to many factors, including lack of sea ice for marine mammals.
Warming also releases human-caused pollutants, such as pole-ward transported mercury and organic pesticides, from thawing permafrost and brings new diseases to Arctic plants and animals, including subsistence food species, posing new health challenges, especially to rural communities.
Greater levels of industrial activity might alter the distribution of species, disrupt subsistence activities, increase the risk of oil spills, and create various social impacts. Native communities must rely not only on improved knowledge of changes that are occurring, but also on support from traditional and other institutions – and on strength from within – in order to face an uncertain future.