Far-reaching Implications |
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While these large shifts in temperature and ice cover appear to be tucked far away in the Arctic, our Earth’s processes are dynamic and interconnected. In other words, rapid loss of sea ice and a warming Arctic will undoubtedly have far-reaching and serious effects for everyone. “Societies have developed and gotten used to climate the way it is now, and changes will very likely be highly disruptive,” Rind says. |
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For starters, as sea ice melts, Arctic waters warm, greatly altering ocean processes, which in turn have an effect on Arctic and global climate, says Michael Steele, senior oceanographer at the University of Washington, Seattle. As the oceans warm and ice thins, more solar energy gets absorbed by the water, creating a positive feedback that leads to further melting and warming. Such mechanisms can change the temperature of ocean layers and impact ocean circulation and salinity, Steele says. For example, the Arctic Ocean during winter is usually very cold and produces lots of sea ice, which creates cold, salty water that sinks to deep levels and drives ocean circulation. But if surface waters warm and ice does not form as well in winter, these processes involving salinity and circulation could be reduced or eliminated. “Then the Arctic Ocean and the North Atlantic Ocean will look very different,” Steele says. Also, if expansive areas now covered by year-round sea ice were to melt and the water were to open up, it could create shipping lanes where none are possible today. While that may be good for some industries, loss of sea ice would also alter wildlife habitats. Polar bears, walrus, and seals, for example, are all adapted to life on sea ice. Indigenous communities based around the Arctic may face enormous changes in terms of both culture and how they meet their people’s basic needs of food, shelter, and clothing. |
Scientists observe a crack in the Ward Hunt Ice Shelf on the northern shore of Canada’s Ellesmere Island. The crack developed between 2000 and 2002, and allowed the waters of a rare freshwater Arctic lake to empty into the Arctic Ocean. The thinning of this 3,000-year-old shelf—the Arctic’s largest—was caused by the climbing temperatures that are also reducing sea ice. (Photograph copyright V. Sahanatien, Parks Canada) | ||
Moreover, Arctic warming and sea ice loss are likely to influence the loss of land ice, says Rind. Temperatures may rise to levels where land ice melts, and feedbacks created by sea ice loss reinforce regional Arctic warming, which in turn could cause more land ice to melt. While sea ice already floats and does not contribute to sea levels, melting land ice adds new water to the oceans. By 2100, sea levels are projected to rise by almost 1 meter (0.9 meters), according to the 2001 Intergovernmental Panel on Climate Change report. Loss of land glaciers, which is already evident, could cause sea levels to rise even further. “Sea levels will continue to rise long after greenhouse gases are stabilized, further endangering coasts and island communities,” says Rind. The loss of sea ice by itself initiates ocean and high-latitude warming regardless of greenhouse effects. | These walruses are taking a rest on a small ice floe in the Bering Sea. Marine mammals living in the polar regions rely on sea ice, and continuing reductions in the amount of ice will harm populations of seals, walruses, and polar bears. (Photograph courtesy NOAA Photo Library) | ||
Additionally, some scientists say Arctic warming could change our atmosphere. If Arctic areas continue to warm, scientists speculate that thawing Arctic soils may release significant amounts of carbon dioxide and methane currently trapped in permafrost. Slightly warmer ocean water may also release frozen natural gases in the sea floor, all of which act as greenhouse gases in the atmosphere, says Rind. However, the extent to which Arctic warming will add greenhouse gases to our atmosphere is a matter of debate. To test the future climate, Rind used the Goddard Institute for Space Studies climate model to run a few simple experiments on how a warming Arctic might impact, say, the state of Kansas. The model was run to test how Kansas might be affected by sea ice loss by itself—that is, without assuming any additional greenhouse warming and without any temperature increases to the oceans. The air over sea ice is generally cold, and when you remove that ice, the air masses above warm considerably. Those Arctic air masses consistently blow south over North America during winter. As a result, the model predicts that sea ice loss will result in warming of over 2 degrees Celsius (4 degrees Fahrenheit) in Kansas in the winter, with a loss of 40 percent of the typical snow cover. “While to some this may sound positive, the vernalization of winter wheat requires subfreezing temperatures; warmer winters would likely require a change in the type of wheat that would be grown which would affect inputs and markets. Worldwide agricultural impacts are likely,” Rind says. In summer, the model tests found that loss of sea ice by itself will raise the temperature a few degrees Fahrenheit and reduce soil moisture in Kansas by up to 10 percent. “Loss of snow cover and associated spring runoff from this reservoir will affect wide regions,” Rind adds. Rind’s simple model simulation clearly illustrates that changes to Arctic ice alone alter climates the world over. And that’s just the start. As the Arctic warms and sea ice declines the ramifications will play out in social, political, and scientific realms. “The implications of Arctic warming can be enormous,” Comiso says.
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The additional warming caused by melting sea ice could also influence glaciers and Greenland’s continental ice sheets. (Photograph courtesy NOAA Photo Library) |
