Thawing Alaskan Lakes This image shows a slice of land near Barrow, on the northern coast of Alaska.

Thawing Alaskan Lakes This image shows a slice of land near Barrow, on the northern coast of Alaska. This area is full of small lakes, many only a couple meters deep, which sit in channels and lowlands carved the last time major glaciers crossed these lands. New research led by scientists at the University of Waterloo shows that these lakes are responding quite rapidly to the area’s warming climate. The European Space Agency’s ERS satellites provided radar data covering these lakes going back for over 20 years. Radar signals are able to penetrate water and ice at these depths and can give information about whether or not the lakes fully freeze. These 2 images are radar coverage of the lakes taken 20 years apart. The dark blue lakes are lakes that are completely frozen at the height of winter; the lighter blue lakes have liquid water still at the bottom of them. As you can see, the number of lakes freezing completely has declined by a lot over the past 2 decades. The change is a combination of 2 factors. First, the lakes are just getting warmer – this area has warmed by almost 2°C over the past 20 years on average. Second, the winter snowfall has started coming earlier in the year, and a thick snowpack helps insulate the lakes and keeps them from melting. Although the melting of these lakes could free up more fresh water, it also poses challenges. The fact that these lakes aren’t freezing fully could allow additional methane to leak out of them, making the atmospheric warming even worse. On top of that, these frozen lakes are occasionally used for transportation, with trucks and equipment driving over them in the winter. If they’re not frozen fully, falling through is an obvious potential problem. -JBB Image credit: ESAhttp://www.bbc.co.uk/news/science-environment-26017431 Original paper:http://www.the-cryosphere.net/8/167/2014/tc-8-167-2014.pdf -- source link

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