Current Arctic Sea Ice Resumes Decline

two polar bears

©2011 Randy Green

After slowing in July, the current Arctic sea ice melt-rate has increased, according to the National Snow and Ice Data Center (NSIDC). Current Arctic sea ice levels has profound implications for polar bear habitat.

The NSIDC reports that though the melt-rate is increasing dramatically as of mid-August, the sea ice extent has not reached the record low of 2007. However, the southern route of the Northwest Passage seems to be open and free of ice.

In other measurements, the Arctic se ice volume is estimated to be below 2007 levels, and possibly at record lows. Sea ice volume is estimated using computer models combining sea ice thickness with the area, or extent of  the sea ice.

One reason volume is important is that the thinner the ice cap, the more susceptible the sea ice is to disappearing, should melt rates again be above normal in future summers.

As Arctic sea ice shrinks, it exposes more of the sea surface to solar radiation. Since open water is darker and absorbs the sunlight that would normally reflect from the white ice surface, sea temperatures will rise, further melting the ice. The disappearance of sea ice is thought by many scientists to be a significant factor in increased global warming.

And, when the extent of sea ice diminishes, it removes much of the habitat used by polar bear populations that spend much of their time in the High Arctic. In addition, Arctic sea ice extent affects the entire Arctic ecosystem, including the seal populations upon which the polar bears depend as their main food source.

Read more about current Arctic sea ice conditions at the National Snow and Ice Data Center.