Arctic Seas Warm as Ice Shrinks

As Arctic sea ice shrank to record lows this summer, sea surface temperatures climbed to record highs in some areas, according to new research from the University of Washington (UW).

Deprived of its usual cover of icy "sunscreen," Arctic water temperatures in an area north of the Chukchi Sea rose to 5 degrees Centigrade (9 degrees Fahrenheit) above average this year, researchers at UW's Applied Physics Laboratory reported. Other parts of the Bering Strait and Chukchi Sea saw water temperatures that were 3 to 3.5 degrees Centigrade (5.4 to 6.3 degrees Fahrenheit) warmer than historical averages.

The findings by Michael Steele, Wendy Ermold and Jinlun Zhang are to be published in the journal Geophysical Research Letters.

"Warming is particularly pronounced since 1995, and especially since 2000," the researchers wrote in their study, "Arctic Ocean Surface Warming Trends Over the Past 100 Years."

Warmer summer waters in the Arctic can affect how ice regrows over the winter, according to Steele. In fact, the researchers have already found that, since summer's end in September, winter freezing in some areas has started much later than usual -- up to two months in some spots.

Steele added the warmer waters make it likely this winter's ice growth will also be thinner than in the past. He estimated this year's sea ice might be 23 to 30 inches thinner than the past average of 80 inches. That's a difference of 28.75 to 37.5 percent.

Those conditions could lead to a feedback loop in future years, Steele said. Thinner, smaller expanses of winter ice make it more likely that even more sea ice will melt in the coming summer. As more reflective ice is replaced by darker open waters that absorb heat from sunlight, Arctic seas are likely to warm even more. That means the following winter's ice growth could be even later, thinner and smaller still.

Warmer Arctic seas could also be helping to drive changes being seen on land in the far north, according to Steele. Some coastal tundra areas, for example, are seeing new types of plants that never grew in the region before.

The National Snow and Ice Data Center reported in October that the extent of Arctic sea ice in the summer of 2007 shattered all previous records, reaching a minimum of 1.65 million square miles. The average extent of summer sea ice between 1979 and 2000 was 2.70 million square miles.

University of Washington, "Without Its Insulating Ice Cap, Arctic Surface Waters Warm to as Much as 5 C Above Average." URL: (http://uwnews.washington.edu/ni/article.asp?articleID=38531)