The Arctic region may be particularly vulnerable to global warming. The average air temperatures in the Arctic between January and August of this year were 3.6° to 5.4°F (2° to 3°C) warmer than the average temperatures for that same period over the last 50 years.
Records show that global temperatures have increased 1°F (0.6°C) in the past century. Most scientists attribute this warming to human activities such as burning fossil fuels.
Researchers warn that the sea ice decline may contribute to even higher Arctic temperatures in the future. While bright ice reflects much of the sun's radiation, dark open water absorbs most of the heat from the sun, making the ocean warmer.
"That means when we get to the next winter we don't get as much growth of ice," Serreze said. "That means it will melt out even easier the next spring. By the end of the summer, you got even more of this open water area, absorbing even more solar energy. As the ocean gets more heat put into it, you have even less ice growth next winter, and so on."
Serreze says the satellite observations are consistent with climate models that predict the sea ice will continue to decline as the Arctic heats up. Some conservative computer models suggest there will be no summer sea ice in the Arctic by the year 2100.
Rising Waters, Shrinking Habitats
Global warming could lead to a rise in sea levels due to thermal expansionas water heats up, it expandsand the melting of above-sea level glaciers. If the Greenland Ice Sheet, the largest ice mass in the Northern Hemisphere, were to melt completely, ocean levels would rise 22 feet (7 meters), scientists say.
Melting sea ice may lead to greater coastal erosion, because Arctic storms could produce much larger waves on the open ocean.
Several remote villages in Siberia and Alaska have already been evacuated due to coastal erosion.
As the sea ice continues to melt, polar habitat also continues to shrink.
"Much of the polar bears' livelihood is [based on] access to that sea ice," Serreze said. "There are some projections that within a century polar bears could be extinct."
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