Arctic Ice Season Shortens by 24 Days as Fewer Lakes Freeze to the Bottom

The winter ice season in the Arctic is 24 days shorter today than it was in the 1950s, according to new research led by University of Waterloo scientists.

Writing in the journal The Cryosphere, the researchers report that not only is the ice season shorter now than it was more than six decades ago, the ice is also thinner - by 38 centimeters at its thickest point.

"We've found that the thickness of the ice has decreased tremendously in response to climate warming in the region," said Cristina Surdu, a PhD student at University of Waterloo who led the research. "When we saw the actual numbers we were shocked at how dramatic the change has been. It's basically more than a foot of ice by the end of winter."

The ice thinning and overall shorter iceing season was documented across 400 lakes on the North Slope of Alaska. The researchers said their study was the first to document the magnitude of lake-ice changes in the region over such a long time period.

"Prior to starting our analysis, we were expecting to find a decline in ice thickness and grounded ice based on our examination of temperature and precipitation records of the past five decades from the Barrow meteorological station," Surdu said. "At the end of the analysis, when looking at trend analysis results, we were stunned to observe such a dramatic ice decline during a period of only 20 years."

Using satellite imaging data, the researchers found that in 1992, 62 percent of the region's lakes were frozen to the bottom, but that by 2011 only 26 percent of the lakes froze solid.

"The changes in ice and the shortened winter affect Northern communities that depend on ice roads to transport goods," said Surdu. "The dramatic changes in lake ice may also contribute to further warming of the entire region because open water on lakes contribute to warmer air temperatures, albeit to a lesser extent than open sea water."