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RENEE MONTAGNE, HOST:
Scientists studying the Arctic say it is warming twice as fast as the rest of the
planet. And they warn there are no signs of that trend letting up. NPR's
Christopher Joyce has the story on the government's annual Arctic report card.
CHRISTOPHER JOYCE, BYLINE: There are no grades for the Arctic in this report
card. It's more of a progress report.
JACKIE RICHTER-MENGE: We really see the power of persistence in the Arctic.
JOYCE: Jackie Richter-Menge is a polar scientist with the U.S. Army Corps of
Engineers.
RICHTER-MENGE: In this particular case, persistence in the warming air
temperatures and the impact that that's having on this icy environment.
JOYCE: Richter-Menge is one of more than 60 researchers from over 13
countries who collaborated with the National Oceanic and Atmospheric
Administration on the report. Their conclusion...
RICHTER-MENGE: It's warming in the Arctic faster than it is anywhere on the
globe.
JOYCE: That's because of Arctic amplification. Here's how it works. Normally,
snow and ice cool the surface by reflecting a lot of the sun's energy back up into
the atmosphere. But warming melts snow and ice.
RICHTER-MENGE: And when they melt, they expose darker regions.
JOYCE: Darker regions underneath absorb more heat, like a dark shirt on a hot,
sunny day. Same thing when sea ice melts; the exposed water is darker and
warms up. So what happens as a result of this amplification? Well, warmer
water affects what lives in it. Apparently, plankton like it warmer. They're
thriving. Unlike plankton, though, polar bears need cold water and sea ice.
RICHTER-MENGE: There's a strong connection between what's going on with
regard to the sea ice cover and the polar bears.
JOYCE: Where the sea ice is holding steady, bears are doing OK. Where the ice
is gone, bear numbers are down. Then there's Greenland. The giant landmass is
covered in ice that's a mile thick. Geophysicist Bea Csatho at the University of
Buffalo has just completed the most comprehensive satellite survey of that ice
cover.
BEA CSATHO: There are some places where, in the last 20 years, the ice surface
is just lowering, lowering, lowering very uniformly.
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JOYCE: Csatho, whose research appears separately in the Proceedings of the
National Academy of Sciences, says she's noticed something else about
Greenland's blanket of ice. Because the ice melts from the top down, the surface
elevation gets lower over time. And at lower elevations, the air generally is
warmer.
CSATHO: As Greenland is losing ice, it gets more and more irreversible because
you get the ice into lower and lower elevations.
JOYCE: The research shows some exceptions to the warming trend - places
where ice is building back or temperatures are cooling. But overall, warming is
winning in the Arctic. Christopher Joyce, NPR News.
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