Sunday, April 30, 2017

An Ice-Free Summer in the Arctic Ocean Would Be Deadly for the Northern Hemisphere

New modeling suggests it could happen as soon as mid-century.

March sea ice extent has been declining by 2.74 percent per decade. (Chart: NSIDC) Click to Enlarge.
Climate scientists don’t like to get pinned down on making date-specific projections about the effects of global warming.  But after months of watching Arctic sea ice languish at a record low, the big question has surfaced once again:  When will we see the Arctic’s first ice-free summer?

According to University of Exeter climate researcher James Screen, the latest modeling suggests that, unless heat-trapping greenhouse gas emissions stop soon, an ice-free Arctic summer will happen as soon as 2046.

“That’s our best estimate, give or take 20 years,” Screen said during an April 24th press conference at the European Geosciences Union conference in Vienna.  The ice decline is clearly linked with rising global temperatures, and the chances that the Arctic will be ice-free increase dramatically when the average global temperature rises between 1.7 and 2.1 degrees Celsius, Screen said.

There’s a good chance an ice-free Arctic Ocean in the summer would have a strong effect on seasonal weather patterns across land areas in the Northern Hemisphere, and it would have big implications for ocean ecosystems.  Polar bears use sea ice to hunt for seals, and a complete meltdown would also affect the blooming cycles of plankton, which serves as food for whales, fish, and birds.  Further, ice-free conditions in the Arctic Ocean would also spur an increase in shipping, fishing, and, potentially, oil and gas drilling.

Screen, an expert on how the melting sea ice affects the path of weather systems around the Northern Hemisphere, said that the regional distribution of ice decline is important.  In recent years, most melting has been in the Barents Sea, which leads to cooling over Eurasia.  That spatial variation means that, as the pattern of melting changes, the effects over land areas will shift as well.

Read more at An Ice-Free Summer in the Arctic Ocean Would Be Deadly for the Northern Hemisphere

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