The Arctic and Its Future
April 2009
Banner photo: © Tim Hibo/Getty Images
A Changing Climate
A melting glacier [Garyhartz/Dreamstime.com] Climate change is being experienced particularly intensely in the Arctic. The Arctic average temperature has risen at almost twice the rate of that of the rest of the world in the past few decades, and there has been widespread melting of glaciers and sea ice and thawing of permafrost (frozen soil). These changes provide an early indication of the environmental and societal significance of global warming. These Arctic changes will, in turn, impact the planet as a whole. For this reason, people outside the Arctic have a great stake in what is happening there.
Climate change is taking place at the same time as many other changes in the Arctic, including an increase in chemical contaminants entering the Arctic from other regions, overfishing, land-use changes that result in habitat destruction and fragmentation, as well as cultural, governance and economic changes. Impacts on the environment and society result from the interplay of all of these changes.
Sea Change
While there are regional variations due to atmospheric winds and ocean currents, with some areas showing more warming than others and a few areas even showing a slight cooling, for the Arctic as a whole, there is a clear warming trend.
The Arctic is warming faster than lower latitudes largely because as Arctic snow and ice melt, the darker land and ocean surfaces that are revealed absorb more of the sun's energy, creating a self-reinforcing cycle of warming.
In Siberia, Alaska and western Canada, winter temperatures have increased as much as 4ºC in the past 50 years. Snow-cover extent over Arctic land areas has declined by about 10 percent over the past 30 years.
Satellite images showing the Arctic sea ice in September, when it reaches its annual minimum, in 1979 (left) and 2007 (right)Arctic sea ice is a key indicator and agent of climate change. Changes in sea ice also have enormous environmental, economic and societal implications. Over the past 30 years, sea ice extent in September (the yearly minimum) has decreased by 31.5 percent or 2.34 million square kilometers, about the size of Germany, France, Italy, Spain, Sweden and the United Kingdom combined, and the melting trend is accelerating. Sea ice has also become thinner in recent decades. It is thought that the Arctic Ocean could be ice-free in summer within decades.
Because the Arctic plays a special role in global climate, Arctic changes have global implications.
Climate change causes sea levels to rise because water expands as it warms, and because land-based ice melts, adding water to the oceans.
Studies suggest that the Greenland ice sheet is melting more rapidly than anticipated. Climate models indicate that the local warming over Greenland is likely to be as much as two to three times the global average, and ice-sheet models project that sustained local warming of that magnitude would eventually lead to a virtually complete melting of the ice sheet, with a resulting sea-level rise of about seven meters.
Carbon is currently trapped as organic matter in the permafrost that underlies much of the Arctic. During the summer, when the surface layer of the permafrost thaws, organic matter in this layer decomposes, releasing methane and carbon dioxide to the atmosphere. Global warming increases these releases, and can create an amplifying feedback loop whereby more warming causes additional releases, which causes more warming, and so on.
An Altered Ecology
The major Arctic vegetation zones include the polar deserts, tundra and the northern part of the boreal forest. Rising temperatures will promote the expansion of forests into the Arctic tundra. The shrinking of the tundra will greatly reduce the breeding area for many birds and the grazing areas for land animals. Not only are some threatened species very likely to become extinct, some currently widespread species are projected to decline sharply.
An arctic fox in summer coat [Michael Haferkamp, GNU] Many animal species from around the world depend on summer breeding and feeding grounds in the Arctic. For example, several hundred million migratory birds migrate to the Arctic each summer and their success in the Arctic determines their populations elsewhere.
In the marine environment, the sharp decline in sea ice is likely to have devastating impacts on polar bears. Other ice-dependent species at risk include ringed seals, walrus and some species of marine birds.
Terrestrial animal species also face threats due to warming. Caribou and reindeer herds depend on the availability of abundant tundra vegetation and good foraging conditions. In winter, lemmings and voles live and forage in the space between the frozen ground of the tundra and the snow, almost never appearing on the surface. Mild weather and wet snow lead to the collapse of these under-snow spaces, destroying the animals' burrows, while ice-crust formation reduces the insulating properties of the snow pack vital to their survival.
Well-established population cycles are no longer seen in some areas. Declines in populations of lemmings, for example, would be very likely to result in even stronger declines in the populations of predators that specialize in preying on lemmings, such as snowy owls, skuas, weasels and ermines.
As water temperatures rise, spawning grounds for cold-water species will shift northward and are likely to be diminished. As southerly fish species move northward, they may introduce new parasites and diseases to which Arctic fish are not adapted. The implications of these changes for both commercial and subsistence fishing in far northern areas are potentially devastating, as the most vulnerable species are often the only fishable species present.
Caribou on the Arctic tundra [Oskarlin /Creative Commons] The effects of rising temperatures are already altering the Arctic coastline. Thinner, less extensive sea ice creates more open water, allowing stronger wave generation by winds, thus increasing wave-induced erosion along Arctic shores. Dozens of Arctic communities are threatened by these changes, and some are already planning to relocate. Hundreds more could be at risk in the future. The costs of protecting or relocating these communities will be enormous. Coastal erosion will also pose increasing problems for some ports, tanker terminals and other industrial facilities around the Arctic.
Marine Access
As summer sea ice retreats, new shipping routes will open, and the period during which shipping is feasible through existing routes will expand.
The Northern Sea Route across the north of Eurasia represents up to a 40-percent saving in distance for journeys from Europe to Asia and the northwest coast of North America compared to southerly routes via the Suez or Panama Canals. The navigation season for the Northern Sea Route is projected to increase from the current 20-30 days per year to 90-100 days by 2080; for ships with ice-breaking capability, the season could expand to 150 days. This could have major implications for transportation as well as access to natural resources.
On the Canadian side of the Arctic, home to the fabled Northwest Passage, near-term benefits are less clear. Recent sea-ice changes could, in fact, make the Northwest Passage less predictable for shipping. High year-to-year variability can make planning for transport very difficult. In addition, a warming climate could lead to more icebergs and greater ice movement in the Northwest Passage, presenting additional hazards to navigation. Thus, despite the widespread retreat of the sea ice, the Canadian Arctic Archipelago is likely to have complex and challenging ice conditions for the decades ahead.
Increased marine access also raises new issues relating to sovereignty, security and safety--for example, the risk of oil spills and other industrial accidents in the challenging Arctic environment.
Across the Arctic, indigenous people are already reporting the effects of climate change. Local land-, sea- and ice-scapes are becoming unfamiliar. Climate change is occurring faster than indigenous knowledge can adapt. Unpredictable weather, snow and ice conditions make travel hazardous, endangering lives. Impacts of climate change on wildlife are having enormous effects, not only for the diets of indigenous peoples, but also for their cultures and their very identities.
The changes already under way in the Arctic provide an early indication for the rest of the world of the environmental and societal significance of global climate change. Changes in climate and their impacts in the Arctic are projected to become much greater. These changes will also reach far beyond the Arctic, affecting global climate, sea level, biodiversity, and many aspects of human social and economic systems.
Susan Joy Hassol, a climate change communicator, analyst and author, was lead author of Impacts of A Warming Arctic, the synthesis report of the Arctic Climate Impact Assessment (2004), and is the director of Climate Communication, LLC.
Robert W. Corell was chair of the Arctic Climate Impact Assessment and is vice president for programs and policy at the H. John Heinz III Center for Science, Economics and the Environment.
This article has been adapted and updated from a chapter in Avoiding Dangerous Climate Change (Cambridge University Press, 2006).
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