Greenland seeing unprecedented melting

Bad Astronomy
The entire universe in blog form
July 24 2012 11:30 AM

Greenland seeing unprecedented melting

Last week, a huge chunk of ice broke off of Greenland's Petermann glacier, an event called a "calving". The iceberg is now moving down the glacier's fjord, as seen by NASA's Terra Earth-observing satellite on July 21, 2012:

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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Note the scale. The iceberg is well over 100 square kilometers in size - about 50 square miles, or 30,000 acres. That's larger than the island of Manhattan in New York City. An even larger iceberg broke off in 2010.

This image comes on the heels of an announcement that Greenland is seeing "unprecedented" melting. By July 12, 2012, as much as 97% of Greenland's ice sheet had experienced some degree of melting. On July 8, just four days earlier, only 40% of the ice had experienced some melting:

[The map shows ice that has had some melting in red, and areas showing no melting in white. The left map is from July 8, the right from July 12.]

This does not mean that 97% of the Greenland ice sheet has melted away! The map shows all the places where at least some melting has occurred. Some of this melting is simply due to it being summer, and in some places there is evidence of a historic cycle of melting. But this widespread a melting has not happened in the 30 years satellites have been used to map the region. Normally, about half the ice on Greenland experiences some melting.

The culprit appears to be several waves of warm high-pressure ridges that have swept over Greenland, each stronger than the last, with the most recent one squatting over the island for about a week.

As always, it's difficult to pin any specific weather event on global warming. But every day, the list of suspicious events grows longer. The Petermann calving happened much farther up the glacier than has occurred before. Waves of warm air over Greenland are unusual. And the weird weather we've been getting is consistent with what's been predicted for a planet that's warming up.

And while climate change deniers put up insulting billboards and compare climate scientists to child molesters, the Earth is getting warmer. While antiscience Congressmen write fallacy-laden op-eds and elected officials run witch hunts against scientists, the Earth is getting warmer.

We need serious people in charge, because it's way, way past time to take this seriously.



Image credits: Terra picture: Jesse Allen and Robert Simmon, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team; Melting map: Jesse Allen, NASA Earth Observatory and Nicolo E. DiGirolamo, SSAI and Cryospheric Sciences Laboratory



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