Eos October 29, 2020

A “timelines of risk” model shows when and where population collapse begins as sea ice wanes in our warming future.ByCheryl Katz<<https://eos.org/articles/polar-bears-to-vanish-from-most-of-the-arctic-this-century>>

With Arctic sea ice in a spiraling decline—2020 was recently declared thesecond-lowest ice yearin the satellite record—it’s an axiom of climate change that polar bears are in peril. But until now, scientists have been unable to pinpoint when and where populations of this charismatic marine mammal will begin to collapse. A novel model combining projections of future sea ice loss by region with calculations of the maximum number of ice-free days polar bears can withstand now gives a timeline for one of the most familiar symbols of global warming.

The outlook is grim. If our greenhouse gas emissions continue at their current high rate, dwindling sea ice will cause nearly all of the 19 polar bear (Ursus maritimus