Climate change puts Arctic winters on thin ice

A press release from the University of Waterloo (Canada): Arctic lakes have been freezing up later in the year and thawing earlier, creating an ice season about 24 days shorter than it was in 1950, a University of Waterloo study has found.

The research, sponsored by the European Space Agency (ESA), also reveals that climate change has dramatically affected the thickness of lake ice at the coldest point in the season: In 2011, Arctic lake ice was up to 38 centimetres thinner than it was in 1950.

“We’ve found that the thickness of the ice has decreased tremendously in response to climate warming in the region,” said lead author Cristina Surdu, a PhD student in Waterloo’s Department of Geography and Environmental Management. “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, so it’s very significant.”

The study of more than 400 lakes of the North Slope of Alaska, is the first time researchers have been able to document the magnitude of lake-ice changes in the region over such a long period of time, says author Claude Duguay, a University of Waterloo professor and member of the Interdisciplinary Centre on Climate Change.

The research team used satellite radar imagery from ESA to determine that 62 per cent of the lakes in the region froze to the bottom in 1992. By 2011, only 26 per cent of lakes froze down to the bed, or bottom of the lake. Overall, there was a 22 per cent reduction in what the researchers call “grounded ice” from 1992 to 2011.

Researchers were able to tell the difference between a fully frozen lake and one that had not completely frozen to the bottom, because satellite radar signals behave very differently, depending on presence or absence of water underneath the ice....

Ekutna Lake in Alaska, shot by Frank K., Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license