Alaska: Climate Change Ground Zero
New climate system emerges in Alaska and the Arctic
The Earth’s temperature is now increasing faster than anytime in the last 1,000 years. In Alaska and the Arctic, temperatures are rising at twice the global rate—more rapidly than anywhere else in the world, making the region ground zero for climate change. The best estimate is that human activity is responsible for all of the observed increase in global temperatures since 1985. The effects of the temperature changes are transforming a once-frozen seascape into an evolving, navigable ocean. These rapid changes occurring in the North have created a new Arctic climate system.
This briefer highlights the signals, risks and costs of climate change in Alaska and the Arctic, including those associated with worsening wildfires, permafrost thaw, melting sea ice and glaciers.
Arctic temperatures are rising
Alaska has warmed more than 3°F (1.7°C) over the past 60 years—a rate more than twice that of other US states—and the average winter temperature in Alaska has increased by 6°F (3.3°C), a temperature change nearly half of the temperature change that ended the last ice age. In 2014, Anchorage experienced no days below zero for the first time since temperature monitoring began. On June 17, 2015, Anchorage saw its warmest day on record, with a high of 83°F (28.3°C), breaking the previous all-time record of 82˚F (27.7°C) set in 1969. In March, the 2015 Iditarod was forced to move 225 miles north due to warmth and lack of snow. Also in 2015, Alaska experienced its hottest May temperatures in 91 years of record-keeping, 7.1°F (3.9°C) above average. It was so hot that on May 23 Fairbanks recorded a temperature of 86˚F (30°C) and the Arctic town of Bettles, a temperature of 82.4°F (28°C), the same day Arizona recorded a high of 82.4°F (28°C). As one reporter put it, “The state with the Arctic Circle running through it [was] warmer than most of the US.” All this heat at the start of 2015 caused early snowmelt and the drying out of the Alaskan landscape.
Scientists are actively studying the processes that amplify the Arctic’s extreme sensitivity to global temperature change.
Most of the warming has occurred since the mid-1970s, due to a combination of global warming and a switch in 1976 from the cold to warm phase of the Pacific Decadal Oscillation (PDO), a large-scale climate pattern. However, despite the PDO’s switch back to the cold phase from 1998 to 2002 and 2007 to 2012, Alaska and the Arctic region have continued to see a rapid rate of average temperature increase. In Barrow, Alaska—the northernmost city in the US—the temperature from 1972 to 2008 was 5.2°F (2.9°C) above average. Throughout Alaska, the average temperature in 2014 was 35.6°F (2.5°C), a substantial 3.0°F (1.67°C) increase over the 30-year average of 32.6°F (0.33°C). Rapid temperature increase is projected to continue, with future warming likely to be greatest in the Arctic.
Warming fuels extreme wildfires
Persistent heat and drought conditions in Alaska fueled an extreme wildfire season in 2015. A swath of land the size of Massachusetts, comprising more than 5.1 million acres, burned across the state, making it the second-worst wildfire season on record. This is the latest in a trend towards more severe wildfire seasons that is consistent with regional climate change forecasts. The number of large wildfires over 1000 acres increased rapidly in the 1990s, and the 2000s saw nearly twice as many large fires as the 1950s and 1960s. By mid-century, models predict that Alaska could see a 150 to 390 percent increase in the area burned by wildfires each year, due to higher surface air temperatures linked to climate change.
The Arctic region of Alaska is seeing the most dramatic increase, with the number of large wildfires increasing nearly tenfold in the 2000s, compared to the 1950s and 1960s. Alaska’s 2015 wildfire season began with two arctic tundra fires, after low precipitation left the region exceptionally dry. The largest tundra fire in recorded history occurred in 2007, north of the Arctic Circle—the fire burned 256,000 acres over a period of almost three months, and marked the first time fire had burned in the area in at least 5,000 years. The tundra fire of 2007 released as much carbon into the atmosphere as the tundra has stored in the previous 50 years.
Increased wildfire frequency worsens air quality and causes harmful respiratory and cardiovascular health effects. Wildfire smoke contains particulate matter and toxins known to cause early mortality and morbidity and can significantly worsen air quality both locally and far downwind, lasting for days or months. Smoke from June 2015 wildfires burning in Alaska and Canada drifted hundreds of miles, creating a hazardous haze all the way to Washington D.C. Research indicates that an increase in patient admissions at hospitals due to poor air quality can be linked to wildfire smoke as far as 200 to 300 miles away from the impacted area.
Average annual fire suppression costs have soared since the 1990s, from $1 billion to $3 billion. In 2015, the US Forest Service spent more than half its budget preparing for and fighting fires—the vast majority of which occurred in Alaska—compared to just 16 percent in 1995. Ten years from now, the agency’s fire suppression costs are projected to increase from just under $1.1 billion in 2014 to nearly $1.8 billion.
Fire suppression costs are only a fraction of the true costs (including property losses, healthcare costs, lost revenues, etc.) associated with a wildfire event. The total cost of US wildfires is presently estimated to be between $20 billion and $125 billion annually. With climate change, that number could climb drastically, adding $10 billion to $62.5 billion to the annual cost of wildfires within just four decades. In today’s economy, that’s about $80 to $500 per American household.
Alaska’s wildfires are not only worsening due to climate change; they also cause climate change to worsen. This is because Alaska’s land and subsurface store vast carbon and methane reserves. In addition to burning and releasing the carbon stored in trees, wildfires in Alaska burn through the land’s organic and carbon-rich surface soil, uncovering frozen soil underneath, known as permafrost. If permafrost becomes exposed, it can thaw and release vast amounts of carbon dioxide and methane. The more severe the fire, the more deeply the Earth is scorched, and the more warming we can expect.
Permafrost, the Arctic's glue, is melting
"Permafrost is the most important part of the ecosystem for engineering in Alaska. When you thaw the permafrost, everything falls apart."
-- Larry Hinzman, hydrologist and director of the International Arctic Research Center
Permafrost lays underneath about 80 percent of Alaska’s surface. It is thickest and widespread in northern Alaska, diminishing to a permafrost-free region in the far south. 70 percent of permafrost land in Alaska is vulnerable to land sinkage due to the steady rate of permafrost thaw. In Fairbanks, rising temperatures have already led to permafrost loss that has damaged forests as well as roads, buildings, and other infrastructure. Both the temperature and extent of permafrost are highly sensitive to climate changes. In the arctic region of Alaska, permafrost warmed up to 5.4°F (3°C) from 1980 to 2000. Over the same period in the subarctic region—home to Alaska’s boreal forest—permafrost warmed 0.5-1.8°F (0.3°C-1°C) and is already beginning to thaw.
Collapsed permafrost block of coastal tundra on Alaska’s Arctic Coast. USGS
Some climate models project that near-surface permafrost will be lost entirely from large parts of Alaska by the end of this century. Some areas such as Fairbanks—Alaska’s second-largest city—are particularly vulnerable, because the ground temperature now hovers near the thaw point, making the permafrost less stable and prone to thawing unevenly.
Thawing permafrost presents considerable challenges for infrastructure maintenance. One study has estimated that the cost of maintaining Alaska’s public infrastructure will increase by 10 to 20 percent ($3.6-$6 billion) in 2030 due to warming, with roads and airports accounting for about half of this cost. By 2080, that tally could rise another 10 to 12 percent ($5.6 billion to $7.6 billion).
Permafrost contains about 50 percent of the global soil carbon. The release of CO2 and methane from thawing arctic permafrost represents another critical feedback loop triggered by global warming. The melting of frozen methane in thawing permafrost is judged likely to have been one of the mechanisms in past abrupt warming events when global temperatures spiked by as much as 11˚ F (6.1°C). As long as permafrost remains frozen, it locks away massive reserves of carbon and methane. However, due to the changes in temperatures and permafrost thaw, the global boreal forest may have already started transitioning from a carbon sink to a carbon source—meaning the boreal forest is likely adding more carbon to the atmosphere than it is absorbing.
None of the models used to inform estimates of warming (such as those cited elsewhere here) account for carbon emissions from permafrost warming. In its most recent climate report, the UN Intergovernmental Panel on Climate Change states, “There is high confidence that reductions in permafrost extent due to warming will cause thawing of some currently frozen carbon,” but also that, “there is low confidence on the magnitude of carbon losses through CO2 and CH4 emissions to the atmosphere.” Recent evidence suggests that there will be a gradual and prolonged release of carbon and methane emissions from permafrost in a warming climate, though the magnitude and timing of these emissions remains uncertain.
Melting ice exposes seas to further warming from the sun
Climate change is reducing both the extent and thickness of Arctic sea ice, exposing previously ice-covered water to heat from the sun. Ocean temperatures in all the Arctic’s marginal seas bordering the continents are increasing. The most significant upward trend is in Alaska’s Chukchi Sea, where surface temperatures are rising by 0.9°F (0.5°C) per decade. In 2014, the Bering Strait region (which includes the Chukchi Sea) saw surface temperatures as much as 7.2°F (4°C) above the 1982-2010 average.
There has been a rapid and substantial decline in summer sea ice extent. The summer Arctic sea ice minimum in September is decreasing at a rate of 13.3 percent per decade, and the past seven years have seen the lowest ice extents ever recorded. Alaska’s Beaufort and Chukchi Seas witnessed a 44 percent and 46 percent increase in open ocean water, respectively, for the month of October from 1921 to 2012. Over the same time period, Barrow, the Northernmost community in Alaska, observed a 13°F (7.2°C) increase in October temperatures, due to the large amount of open water in the Chukchi and Beaufort Seas. At its minimum, sea ice covers about half of the area it did in 1979, when records began. Sea ice minimum, however, is not the only ice metric showing signs of global warming. In February 2015, the Arctic maximum sea ice extent was the smallest on record, as well as one of the earliest.
The trends in maximum and minimum sea ice extent are driven by an overall thinning and decrease in ice extent. Sea ice extent decreased by 3.8 percent per decade from 1979 to 2012, and winter thickness thinned by 1.8 meters from 1978 to 2008. As sea ice becomes thinner overall, with less ice lasting over multiple years, the ice becomes more vulnerable to further melting.
The models that best match historical trends project that, by the 2030s, northern waters will be virtually ice-free in late summer. As with thawing permafrost, reduced sea ice extent amplifies global warming. Sea ice cover acts as a shield between the Arctic Ocean and atmosphere, preventing the ocean from absorbing the Sun’s energy. As sea ice melts, there is more open ocean to absorb this energy. The additional heat causes more ice melt, leaving more open ocean water to absorb even more heat.
Melting glaciers are causing the oceans to rise
“Because the global glacier ice mass is relatively small in comparison with the huge ice sheets covering Greenland and Antarctica, people tend to not worry about it. But it's like a little bucket with a huge hole in the bottom: it may not last for very long, just a century or two, but while there's ice in those glaciers, it's a major contributor to sea level rise."
-- Tad Pfeffer, CU-Boulder Professor and glaciologist at CU-Boulder's Institute of Arctic and Alpine Research ICESat.
Mountain glaciers—as opposed to continental ice sheets—represent less than 1 percent of the Earth’s glaciers in terms of volume, but their rapid rate of mass loss accounts for nearly one third of the current observed sea level rise. Melt from Alaska's glaciers and other glaciers around the world contributed as much to global sea rise as the Greenland and Antarctic ice sheets combined from 2003 to 2009.
Glaciers form when snow accumulates over several years and transforms to ice. Once formed, gravity forces glaciers to flow to lower elevations where temperatures are warmer, causing the ice to melt. Whether or not a glacier shrinks on average depends directly on atmospheric conditions. From 2003 to 2009, all glacial regions shrunk. Alaska was among the regions that saw the greatest loss of ice, with about 75 percent of 46 glaciers measured in Alaska and northwestern Canada shrinking at an increasing rate.
Glacier mass and areas in 19 regions. Gardner et al. 2013
Climate change threatens ecosystems & native communities
“The rapid rate at which climate is changing in the polar regions will impact natural and social systems and may exceed the rate at which some of their components can successfully adapt.”
Alaska’s arctic and boreal regions have diverse and dynamic ecosystems which are sensitive to climate change. All of the changes described in the previous sections affect Alaska’s ecosystems. Already, warmer air temperatures have altered water availability and flows. Permafrost thaw has changed vegetation patterns. Changes to the availability of different nutrients is causing competition among plant species. In the high northern latitudes, shrubs and grasslands are expected to shift to boreal forests. Increasingly frequent and severe fires are leading to a shift in forest composition and distribution. Storm surges enhanced by sea-ice retreat have led to increased coastal erosion and salinization. As warming continues, one comprehensive study looking at 60 different environmental indicators found that shrub and tree expansion, fire, permafrost thaw and movement of plant and animal species will be the major drivers of ecological change through 2100.
Alaskan natives are experiencing climate change impacts firsthand through destructive coastal erosion, devastating wildfires, thawing permafrost and other problems that have severe social and economic costs. For example, certain roads in the tundra can only be used when the ground is frozen solid. In the past 30 years, the number of days when travel is allowed on the tundra has decreased from 200 to 100 days per year.
With the exception of oil-producing regions in the north, rural Alaska is one of the poorest areas in the US. Coastal towns and villages are particularly vulnerable to sea level rise and more frequent and intense storms. In at least three western Alaskan villages, the erosion of coastal areas and increased flooding events are forcing residents to relocate from established areas, making these communities some of the first environmental migrations that can be directly linked to climate change. In the coastal community of Shishmaref, increased windiness and storminess, increased erosion and diminished sea ice threaten the community with habitual flooding.
Cost estimates of shoreline protection and native village relocation continue to rise. The Alaska Village Erosion Technical Assistance Program found in 2006 that communities in Kivalina, Newtok and Shishmaref each had 10 to 15 years before erosion would impact critical infrastructure, and the cost to move each village would range from $80 million to $200 million. In 2009, the US Army Corps of Engineers found 178 communities had already reported erosion problems, and the Corps designated 26 of these as “Priority Action Communities,” indicating they should take immediate action to identify solutions or continue with ongoing efforts to manage erosion.
- Age of Alaskan Wildfires, June 2015
- Arctic Report Card, December 2014
- Risky Business—Alaska, June 2014
- Third US National Climate Assessment—Alaska, May 2014
- IPCC AR5, WGI, Chapter 4—Cryosphere, September 2013
- IPCC AR5, WGII, Chapter 28—Polar Regions, September 2013
- Arctic Biodiversity Assessment, May 2013
- Understanding Alaska’s Remote Rural Economy, January 2008
- Alaska Region Climate Change Response Strategy 2010-2014