Wednesday, September 09, 2020

More Grim News About Melting Ice

As if this year hasn't been bad enough, there's more grim news on the climate change front. Recent research shows that the Greenland and Antarctic ice sheets are melting at a rate that would match the worst-case scenarios in the Intergovernmental Panel on Climate Change’s (IPCC) 2015 fifth assessment report. That would raise global sea levels by 17 cm. (6.7 inches) by the end of this century. It doesn't sound like much, but it would have major effects on cities and coastal areas already feeling the effects of sea-level rise.

 “That’s enough to double the frequency of storm-surge flooding in many of the world’s largest coastal cities,” Anna Hogg, study co-author and climate researcher in the School of Earth and Environment at the University of Leeds, said in a statement.

Until recently, the main cause of global sea level rise has been thermal expansion—seawater expanding as it heats up. But over the past five years, the researchers say, ice melt has become the main thing pushing up the world’s oceans. The new research follows an August study which found Antarctica’s ice sheet is becoming vulnerable to quick destruction by melt water seeping into its fractures. And on the other side of the world, research published earlier this year found that sunny skies added to the woes of last year’s record Greenland melt. Plenty of smaller sources of ice are also becoming problematic, from disappearing glaciers in the Alps to Iceland.

Alarmingly, the study authors say that since sea level rise is already meeting scientists’ worst-case projections, the actual worst case could be even more severe. It may require completely reimagining the climate models used to estimate sea level rise.

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