An unusual polynya, an area of open water surrounded by ice in the center of the image, formed during the melt season in the Beaufort Sea. To the left is the coastline of Alaska, showing fall foliage color, and to the bottom right is the North Pole.
Image credit National Snow and Ice Data Center
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New development of a polynya .....
A notable feature of the 2006 melt season was the development of a large polynya, which is an area of persistent open water surrounded by sea ice, north of Alaska.
When it was near its largest area in early September, the polynya was the size of the state of Indiana.
How the polynya formed is not clear. Unusual wind patterns may have forced the ice cover to spread apart. Scientists also speculate that thin ice moved into the area over the winter, melting out over the summer and creating the polynya. Another possibility is that warm waters rose to the surface.
NSIDC Lead Scientist Ted Scambos added, “Arctic sea ice is an important climate indicator because it's so sensitive to this initial warming trend.” As sea ice melts in response to rising temperatures, it creates a positive feedback loop: melting ice means more of the dark ocean is exposed, allowing it to absorb more of the sun’s energy, further increasing air temperatures, ocean temperatures, and ice melt.
The observed changes in the ice cover indicate that this feedback is now starting to take hold. Sea ice is only one indicator of Arctic change amongst many, such as warming of permafrost, changing patterns of vegetation from tundra to shrubs, a warming ocean, and accelerated melt of the Greenland ice sheet.
“I’m not terribly optimistic about the future of the ice,” Serreze said. “Although it would come as no surprise to see some recovery of the sea ice in the next few years—such fluctuations are part of natural variability—the long-term trend seems increasingly clear. As greenhouse gases continue to rise, the Arctic will continue to lose its ice. You can’t argue with the physics.”
Data for this article was provided by the National Snow and Ice Data Center, Boulder, Colorado.