Climate change is causing the Arctic to warm more quickly than the rest of the world, causing a dramatic loss of Arctic sea ice. For at least 800,000 years, the Arctic Ocean has had at least some sea ice throughout the year. Today, sea ice loss is occurring even more rapidly than models predicted just a few years ago. As warming seas cause its ecosystem to restructure, the Arctic is becoming a different place.
Global Effects of Arctic Warming
© Harper Simmons courtesy of the International Arctic Research Center
Arctic sea ice is carried southwards into the North Atlantic, where it melts. The resulting volume of relatively fresh water affects the ecology of the area and helps drive the worldwide circulation of the ocean. Changes in recent decades have had profound effects, including the transition from cod to shrimp in Greenlandic waters. Climatologically, changes in freshwater inputs to the North Atlantic may alter the global ocean currents with far-reaching effects.
Arctic Marine Ecosystem Restructuring
In the Arctic, the consequences of sea ice loss and ocean warming are a comprehensive restructuring of marine ecosystems. Without sea ice, the interactions between atmosphere, water and animals will all change. The system is too complex and our knowledge too limited to predict what will happen in any detail. But the broad outlines are clear.
Walrus in the Bering Sea
© B. Christman, NOAA
Thinner ice threatens hunters who spend time on the ice traveling or in pursuit of fish and marine mammals. Sea ice can be dangerous at the best of times but it becomes even more precarious when knowledge of local patterns is no longer as useful. If the ice retreats too quickly, hunters may have little chance to find marine mammals such as walrus and bearded seals that live among the ice floes.
A recent assessment of the implications of climate change on Arctic marine mammals found that narwhal, polar bear and walrus are among the most susceptible animals. The assessment also found that subarctic marine mammals will benefit at the expense of today’s true Arctic species.
Further down the food web, changes are harder to anticipate. Subarctic species may move north but oceanographic conditions and other variables are not the same as their current habitats. Food webs may shift favoring jellyfish or small invertebrates that are not suitable food for today’s predators.
Responding to Climate Change in the Arctic
Major assessments such as the Arctic Climate Impact Assessment have tried to ascertain the trajectory of climate change and its implications for ecosystems and people. It is clear that many challenges lie ahead. But it is far less clear how humans can best respond to sustain species and subsistence ways of life that thrive under Arctic conditions.
Oceans North is working to ensure that new industrial access to the North American Arctic made possible by the melting ice pack does not further destabilize a rapidly changing ecosystem. At the same time, the The Pew Charitable Trusts supports policy and science including the Pew Campaign on Global Warming – to limit greenhouse gases to levels that will keep the Arctic frozen.
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Hamilton, L.C., B.C. Brown, and R.O. Rasmussen. 2003. West Greenland’s cod-to-shrimp transition: local dimensions of climatic change. Arctic 56(3):271–282.
Laidre, K.L., I. Stirling, L.F. Lowry, Ø. Wiig, M.P. Heide-Jørgensen, and S.H. Ferguson. 2008 Quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. Ecological Applications 18(2) Supplement: S97-S125.
Lawrence et al. 2008. Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss. Geophys. Res. Lett Geophys. 35: L11506.
Moore, S.E., and H.P. Huntington. 2008. Arctic marine mammals and climate change: impacts and resilience. Ecological Applications 18(2) Supplement: S157-S165. http://www.esajournals.org/toc/ecap/18/sp2.