Massive Melt In Greenland

For the upcoming issue, I got to interview Michael E Mann, the director of the Earth System Science Center at Pennsylvania State University and one of the researchers behind the famed hockey stick graph.  I asked him if there’s a new piece of evidence for climate change that he finds particularly compelling. He said he couldn’t pick just one because he sees new, compelling evidence almost every day.

And as it happens, I’m looking through the science news last night, and sure enough, I come across a story about how almost all of Greenland’s surface ice vanished over four days in July.


From the NASA website:

For several days this month, Greenland’s surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland’s ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

And here’s a pic of that melt. On the left, a July 8, 2012 satellite image. On the right, one from July 12, 2012. White is surface ice, light pink is probable melt, dark pink is actual melt.

And in case you think this is just some kind of data error, the melt has been confirmed by three satellites.

Author: Paul Dechene

Paul Dechene is 5'10'' tall and he was born in a place. He's not there now. He's sitting in front of his computer writing his bio for this blog. He has a song stuck in his head. It's "Girl From Ipanema", thanks for asking. You can follow Paul on Twitter at @pauldechene and get live updates during city council meetings and other city events at @PDcityhall.

19 thoughts on “Massive Melt In Greenland”

  1. You know those disaster movies, where the heroes figure out before everyone else that the world is coming to an end, and act to prevent it (or at least save themselves)? Maybe it’s more likely that the world ending landmark events will get a 3 minute mention on some newscasts after the local and international shooting stories.

  2. I recall hearing years ago that one concern about Greenland and Antarctica melting especially, where that the ice is up on land, so when it runs off into the ocean, sea levels rise a great deal. The north polar ice cap is at least in water already, so it won’t affect the sea level quite as significantly. The salt content of the ocean could change to an important degree too, however.

  3. Talbot: Not quite. It’s the surface ice. Normally, about 50 per cent of the surface ice cover does start to melt in a Greenland summer. What’s weird and worrying here is that almost all of Greenland has started to melt and it happened over a really short period of time.

    I’ve been reading more on this since putting up the original post and apparently there’s ice core evidence to suggest that a melt event like this happened 150 years ago. So this news from NASA might just represent an occasional weather anomaly and not a sign of an impending catastrophe.

    But something that lends credence to the “Greenland’s ice shelf is collapsing” catastrophe idea is that just after this melt event, an iceberg broke off Greenland’s Petermann Glacier — an iceberg with a surface area larger than Manhattan.

  4. @ John #4: melting ice will raise the ocean’s levels no matter whether the ice is on land or in the water. Think.

  5. @Barb#7
    If i fill a glass with ice and then fill it wiht water to the rim, what happens to the water level when the ice melts?

  6. #8 nothing, except that you have have a full glass of slightly warmer water.

    #7 Don’t glaciers melt & create rivers that flow into the oceans almost all year round? I could be wrong tho’.

  7. @anonymous #8: the glass is sitting on my counter right now.
    @Ron #9: they can. Our river system in North America is the result of past major glaciation.
    I don’t know how thick the Greenland icesheet is, but ancient North America’s is estimated to have been several km thick. When it melted and retreated, it not only created lakes and rivers, it also allowed the continent to rise in elevation because the weight had been removed (isostatic rebound). This is still going on.

  8. Result of the experiment: inconclusive.
    As the volume of ocean is greater than the glaciers’, I half-filled a glass with ice cubes and filled the rest to the brim with water. The ice has melted and I have what looks like overflow, but as I cannot control for relative humidity, that water could be condensation, rolling down the outside of the glass.

  9. Did a bit of reading on this question because I didn’t trust my common sense notions on the subject.

    Looks like if the floating arctic ice melts, that melt water won’t affect sea level because the ice sheet rises and displaces less water.

    However, sea level will be affected by the thermal expansion of the ocean as it warms. Also, as the sea ice disappears, it no longer buttresses the glacial ice, so the Greenland and Antarctic ice sheets will deteriorate more quickly and that melt water does cause the ocean levels to rise.

    Then there’s the albedo effect. Ice reflects energy back into space and as ice cover shrinks, the planet warms more quickly.

    And finally, as John points out, adding fresh water to the oceans decreases its salinity and this has a bunch of impacts that scientists are still trying to figure out. Less-salty water is apparently less dense and that affects ocean currents. And, because less-salty water evaporates more quickly than salty water, the water cycle accelerates.

    Anyway, looks like the arctic melt water doesn’t directly cause sea levels to rise. But indirectly, a melting arctic does contribute to more rapid sea level rise.

    And regardless, a melting Greenland is a very bad thing.

  10. @Paul #12: unless, of course, it’s an anomaly, as noted in para. #2, comment #5.

  11. Barb: If this melt occurred in isolation then maybe it could be dismissed as an anomaly. But it hasn’t. The scientists who are alarmed by this event feel that way because this is one more link in one of the chains of evidence to suggest the Greenland ice sheet is in danger.

    A related point: Back in the 80s, the number of hot weather records broken in a year more-or-less matched the number of cold weather records that were broken. Nowadays, hot weather records are being broken 10 times more often than cold weather ones.

  12. As stated in #9 nothing.
    Yer right #11 it was just condensation.
    I did the experiment tonight.

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