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NASA Satellite Measurements Show Unprecedented Greenland Ice Sheet Melt

Posted by Soulskill on from the cave-man-army-activated dept.

NASA reports that measurements taken from orbiting satellites indicate the Greenland ice sheet underwent melting over a larger area than they've seen in 30 years of observations. On July 8, the satellites found evidence that about 40% of the ice sheet's surface had melted. Observations just four days later showed 97% of the surface had melted. "This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. 'Each successive ridge has been stronger than the previous one,' said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate. Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12." Photos also surfaced last week showing the Petermann Glacier in Greenland 'calving' — some very large chunks of it broke off and started to drift away.

13 of 411 comments (clear)

  1. I'm not going to panic just yet... by oraclese · · Score: 5, Informative

    At the risk of sounding like a denier, I'm not going to freak out just yet, since it says in the article (and partially in the summary) that this is believed to happen every 150 years or so, last time being 1889.

    1. Re:I'm not going to panic just yet... by haruchai · · Score: 1, Informative

      Anthony Watts denialist site: WattsUpWithThat.com

      Sorry, thought it was better known around here. They sure get their thongs stuck in awkward places when Slashdot posts a pro-AGW story.

      --
      Pain is merely failure leaving the body
    2. Re:I'm not going to panic just yet... by dr2chase · · Score: 5, Informative

      That, I'm pretty confident they have right. Big volcanos leave world-wide signatures in the ice, these can be cross-referenced to tree rings, varves (fucking spell-check, "varve" is a word, it's layers of mud at the bottom of lakes), sometimes even historical records.

      (There, glaciology in three or fewer sentences :-)

    3. Re:I'm not going to panic just yet... by silentcoder · · Score: 2, Informative

      >Remember: approximately the last 10 years have NOT been increasing significantly in temperature.

      False. Most AGW-deniers claim that but they are wrong- there was heating over the past ten years and the past decade was the hottest in recorded history. It is also true that most AGW-proponents over-estimate the DEGREE of the heating in the past decade. Most believe an average of 5 Degrees Celcius per year, the actual figure is more like 0.5 C per annum.
      That's still huge by climatologists standards though.

      --
      Unicode killed the ASCII-art *
    4. Re:I'm not going to panic just yet... by silentcoder · · Score: 4, Informative

      >And by the way: they have NOT "all" been pointing in the same direction. Here, for example, we've had close to record cool Springs and early Summers for the last two years. In fact most of last summer was fairly cool, as well.

      Those actually DO point in the same direction. Any climatologist will tell you that an increase in the average temperature of the planet will cause some places to actually become colder (at least in the short term). This is not all that surprising, the increased temperature in most places causes changes in various weather patterns, in some cases it could cause polar cold fronts to move into areas they previously didn't often reach (pushed there by warmer air in regions they used to) - and so cool those places down (just one of many examples).
      Warmer climate over-all means more rain, which in some areas (usually not the same ones where the warmth was) would mean more cloud coverage. You could see colder temperatures in some places because of more rain - and ultimately flooding - exactly because of the over-all increase.

      That's not an argument in the debate either way. Climate is about the AVERAGE over many measurements in many places, and that average is indeed going up.

      --
      Unicode killed the ASCII-art *
    5. Re:I'm not going to panic just yet... by Rei · · Score: 5, Informative

      To have to delve into this again: Both Greenland and Iceland have icy areas and "green" areas; Iceland has a larger percent of "green" areas to be sure, but that doesn't stop it from having the largest glacier in Europe and getting lots of snow every winter, nor does it mean that there aren't even forests (albeit stubby) in Greenland.

      Iceland was named by Flóki Vilgerðarson, who witnessed drifting pack ice during his first winter in Barðaströnd in Vestfirðir (the West Fjörds), something unknown in southwestern Norway where he was from (to be fair, it's relatively rare in Iceland, too, but not nearly so rare as in southwestern Norway). Must have seemed crazy to him, to see the sea itself frozen.

      Greenland was named (although not discovered), as mentioned, by Eiríkr (TH)órvaldsson (commonly known as Erik the Red). He landed in the southwest side of Greenland. Look at the southwest side of Greenland in Google Maps with the satellite layer on and tell me what you see. It's green. There are quite significant areas of non-glaciated land there, which is why that's where Greenland's population lives. Greenland, as a whole, was not "melted" then "frozen" and now "melting again" on the order of a thousand years; that area has been, in historic times, constantly ice free, while most of the island has, likewise, been constantly ice covered. There's been advance and retreat of glaciers, but nothing so dramatic as what people are talking about here.

      As for "Grænland": first, think of what was known about Greenland before Eiríkr. It's said that on a very clear day you can see Greenland from certain parts of Vestfirðir, although I've never tried myself. It's about 300 kilometers. About 50% of days here during the summer in Reykjavík we can see details on Snæfell which I think is something like 150 kilometers away, so I wouldn't discount it. If you could see it, all you'd see was icy mountains. Then Gunnbjarnarsker (Grunnbjörn's Skerries) were discovered off the Greenland coast before Eiríkr, which Snæbjörn Galti tried (and horribly failed) to colonize. The east coast of Greenland and the straits are just too harsh. But, exiled from Iceland for three years for murder, Eiríkr sailed through icy seas, and along the frozen coasts of Greenland, and then discovered... well, green. And lots of it. So should it really be a surprise that he named it that? Yes, the saga says that he wanted to give it a good name to encourage colonists, but that wasn't unusual; to him, it compared similarly to Iceland. He wasn't calling a frozen rock "green" to trick people.

      --
      "99 dead duelists of Dios on the wall. 99 dead duelists of Dios! Take one's ring, pass it around..."
    6. Re:I'm not going to panic just yet... by dr2chase · · Score: 4, Informative

      "Ice rings", means you get 6 months of really-really cold, and 6 months of not so cold. It leaves some sort of mark in the ice. To build up a kilometer or three of ice, the net has to be ice growth.

      In the past the earth has witnessed CO2 concentrations like what we have today, and the heat followed (strictly speaking, they happened roughly simultaneously in the past because the CO2 concentrations did not rise so quickly. It takes a really long time to heat the ocean. Our CO2 is ahead of the heat, and we will not reach equilibrium for hundreds of years). Over time, that heat caused ice caps to melt and/or slide into the ocean, raising sea levels quite a bit.

      In the distant past, with very high CO2 concentrations, we had very high temperature increases and mass extinction. If we continue on our present trends ("business as usual", or BAU, in many discussions) we're expected to hit 1000ppm CO2 by 2100, which is well above what it took to melt ice caps (given time), and within perhaps a factor of two of the levels leading to the mass extinction. This is still unclear, the fossil record is old, the climate models have to work with a different configuration of continents and an allegedly cooler sun, and it's not clear exactly how much CO2 was needed to start the heat, versus how much resulted from liberated CH4 degrading to CO2 and stuff dying and rotting. Do we feel lucky?

      The problem for us is that if we were preceding slowly to a somewhat-higher CO2 world (i.e., early Pliocene), we would get a wetter climate, which is not that bad (fresh water is good, though sea levels will be 25 meters higher). But we're not proceeding slowly; we're turning up the heat in a relatively large way. The oceans have a huge thermal mass, and though they absorb the bulk of the heat, their temperature rises more slowly than the land temperature. The result, "temporarily" (for a few centuries) is a slightly lower relative humidity, meaning, less rain, aka, more drought. Furthermore, the likely shrinking of the ice caps will proceed through accelerated sliding into the ocean, not melting in place, which will tend to cool the ocean somewhat. (All this is extremely hand-wavy, and says nothing about changes in ocean currents, which can have a very large regional effect.) See
      http://earlywarn.blogspot.com/2011/12/pliocene-wetter-than-today.html for a more detailed discussion.

  2. Atlantic Currents by gznork26 · · Score: 5, Informative

    With that much fresh water being added to the North Atlantic, we ought to be talking about the health of the Atlantic Ocean currents that are energized by the temperature difference between equator and polar regions, and the deep water exchange, which is driven by the difference in salinization. Most important of these currents is the Gulf Stream. It stopped several hundred years ago, over the course of a single lifetime, and caused the Little Ice Age in Europe. I've already heard some reports about the speed of the current slowing. An awful lot depends on those currents, and we've heard nary a peep about the implications.

    1. Re:Atlantic Currents by phantomfive · · Score: 5, Informative

      and we've heard nary a peep about the implications.

      I don't know why you haven't heard a peep, scientists have taken this quite seriously and have done some research on the topic. The difficulty, of course, is good historical data is hard to find, and frankly, good measurements of the entire ocean are not easy to make even now.

      In any case, the latest scientific research suggests little cause for alarm.

      --
      "First they came for the slanderers and i said nothing."
  3. Re:Bright future for Greenland by WillAffleckUW · · Score: 3, Informative

    Well, remember, Greenland was originally settled during a warming period that allowed Britain to grow wine, and the Viking inhabitants only died off when it reverted to colder temperatures.

    I recommend getting there by steamship. Maybe aboard the Titanic II?

    I'm sure it's safe.

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    -- Tigger warning: This post may contain tiggers! --
  4. Re:hottest in thirty years -must be global warming by DJRumpy · · Score: 4, Informative

    According to TFA, they observed this via ice cores, not via some sort of manmade records or anything of that sort (excluding the 30 years of satellite data of course). At this point, they consider this an interesting but non-threatening event, with the proviso that if it happens again in the next year or two, then it will be much more concerning.

    From TFA:

    "Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. "But if we continue to observe melting events like this in upcoming years, it will be worrisome."

  5. Re:You are the alarmist. by khallow · · Score: 1, Informative

    In all three cases, the economic alarmists were wrong.

    Er, what do you mean by wrong? Obviously the world didn't end. But there was, for example, a mass exodus of the steelworking industry from the developed world of that time. And CFC replacements resulted in higher prices for most things having to do with refrigeration. The point being that there were drawbacks.

    The problem here is that "addressing climate change" or in other words, reducing global generation of greenhouses and in particular, reducing the burning of fossil fuels is a far larger part of the economy than the two examples you give.

    Ye all seem so very confident about it, that you don't even have to learn what scientists and economists have to say on the issue.

    The economists are in agreement that there are substantial costs for AGW mitigation, on the order of some percentage of global GDP hit per year. Where there is disagreement is in how big the hit is and whether it's smaller than the benefit to be gained.

  6. Re:Greenland used to be... by Anonymous Coward · · Score: 2, Informative

    Forgot you pills perhaps??

    The name Greenland comes from the early Scandinavian settlers. In the Icelandic sagas, it is said that Norwegian-born Erik the Red was exiled from Iceland for murder. He, along with his extended family and thralls, set out in ships to find a land rumored to lie to the northwest. After settling there, he named the land GrÅ"nland ("Greenland"), supposedly in the hope that the pleasant name would attract settlers.

    http://en.wikipedia.org/wiki/Greenland

    Maybe you should fix wikipedia page with your awesome original knowledge there?