Satellites reveal sudden Greenland ice melt

 
Nasa images reveal the extent of the  surface melt over Greenland’s ice sheet on July 8 (l) and July 12 (r) The first image shows Greenland's ice sheet on 8 July, the second, taken four days later, shows the area where ice has melted at the surface

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The surface of Greenland's massive ice sheet has melted this month over an unusually large area, Nasa has said.

Scientists said the "unprecedented" melting took place over a larger area than has been detected in three decades of satellite observation.

Melting even occurred at Greenland's coldest and highest place, Summit station.

The thawed ice area jumped from 40% of the ice sheet to 97% in just four days from 8 July.

Start Quote

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”

End Quote Lora Koenig Nasa Goddard Space Flight Center

Although about half of Greenland's ice sheet normally sees surface melting over the summer months, the speed and scale of this year's thaw surprised scientists, who described the phenomenon as "extraordinary".

Nasa said that nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its centre, which is 3km (two miles) thick, experienced some degree of melting at its surface.

Until now, the most extensive melting seen by satellites in the past three decades was about 55% of the area.

According to ice core records, such pronounced melting at Summit station and across the ice sheet has not occurred since 1889.

"When we see melt in places that we haven't seen before, at least in a long period of time, it makes you sit up and ask what's happening," Nasa chief scientist Waleed Abdalati said.

"It's a big signal, the meaning of which we're going to sort out for years to come."

Watch this space

He said that, because this Greenland-wide melting has happened before - in 1889 - scientists are not yet able to determine whether this is a natural but rare event, or if it has been sparked by man-made climate change.

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The observation is in my view much more important than the recently reported break up of a large iceberg from Petermann Glacier”

End Quote Poul Christoffersen Scott Polar Research Institute

"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," said Lora Koenig, a glaciologist from Nasa's Goddard Space Flight Center in Maryland and a member of the research team analysing the satellite data.

"But if we continue to observe melting events like this in upcoming years, it will be worrisome."

Prof Eric Wolff, from the British Antarctic Survey (Bas) told BBC News: "There have clearly been some very warm days in Greenland this month. As a result, the surface snow has melted across the whole ice sheet.

"This is confirmed by some of my international colleagues who are on the ground at the NEEM ice core drilling site in north Greenland - they are reporting several days with temperatures above zero, and ice layers forming in the snow.

"While this is very unusual, as always we cannot attribute any individual extreme event to climate change: We will have to wait and see if more such events occur in the next few years to understand its significance for both the climate and the health of the ice sheet."

Dr Poul Christoffersen, a glaciologist and engineer at the Scott Polar Institute in Cambridge, told BBC News: "The melting seen in the satellite data is unprecedented, as it extends all the way across the ice sheet including the summit, which is located 3,200 m above sea level. Melting is usually limited to less than 2000m elevation."

The news comes just days after Nasa satellite imagery revealed that a massive iceberg, twice the size of Manhattan, had broken off the Petermann Glacier in Greenland.

"The observation [from Greenland] is in my view much more important than the recently reported break up of a large iceberg from Petermann Glacier," Dr Christofferson added.

Nasa's Tom Wagner said: "This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story."

Scientists said they believed that much of Greenland's ice was already freezing again.

 

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  • rate this
    +1

    Comment number 620.

    I've said it before, and I'll say it again, better to prepare and be proved wrong, then be proved right and be unprepared.

    Our industries and agricultures are already shifting. If that is not evidence enough of climate change for someone, they are fools.

    This shift must be monitored, watched and reacted to - even making changes ready for it! Otherwise, we could suffer far worse.

  • rate this
    +2

    Comment number 619.

    “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,” : Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. This is not unprecedented.

  • rate this
    -6

    Comment number 618.

    Waleed Abdalati, I'll save you a lot of time and expense, the Greenland ice melt isn't down to 'Man Made' Global Warming. But then that 'theory' is probably funding your salary for the next 20 years!!!

  • rate this
    +6

    Comment number 617.

    609. ConnorMacLeod

    'A gross oversimplification. Temperature & pressure DIFFERENCE is what causes winds. Jupiter & Saturn both have v. high windspeeds but are far, far colder than earth.'

    True. I must confess to being way cynical about much of that the people asking such darn' silly questions are capable of (or desirous of) understanding :) They don't seem to want their questions answered...

  • rate this
    -4

    Comment number 616.

    Well, they did say that this happens roughly once every hundred and fifty years, so it's not even worth batting an eyelid over until it starts to happen more often. Anyway, it's not like it's a new thing for the Earth to be much warmer than it is now. The climate is always changing and always has been.

  • rate this
    +3

    Comment number 615.

    Venus' atmosphere wasn't so different from the Earth's at first. Yet, due to too much GHG concentration, there was ironically speaking, a snowball effect, one which you should not consider 100% unlikely on our own planet. Today, the temperatures on Venus are as high as 450 °C at least.
    http://www.astro.unipd.it/planets/barbieri/schneider/astronomia/CosmicPerspective_Ch10.pdf
    Page 313

  • rate this
    -3

    Comment number 614.

    Nothing to do with global warming, if indeed that exists at all. Ever noted how often we seem to see during the past few years, events which happened between prior to 1920.

    And not all cycles occur even that frequently. Its simply that records do not always exist prior to the past century or so.

  • rate this
    +2

    Comment number 613.

    Whatever the natural cycles of weather on the planet, it seems to me that we have now released billions of tonnes of CO2 into the atmosphere by burning fossil fuels. Before the oil age this CO2 was dormant, captured by plants millions of years ago. The atmosphere has a finite volume. CO2 concentrations are higher than ever. If we didn't do it, where did it come from? CO2 is a known greenhouse gas.

  • rate this
    -5

    Comment number 612.

    I'm not a subscriber to the climate change theory. Millions of years ago forest fires and volcanoes probably pumped more CO2 into the atmosphere than we do. Current ice melt, warming of the planet, and weather are more than likely cycles of Earth's life. We have not been around long enough to see these long term changes which will more than likely reverse naturally in another few thousand years!

  • rate this
    -6

    Comment number 611.

    Why are you all so bothered about Greenland.No one lives there and its miles away.Whats it got to do with anything anyway. I'm all for global warming.I'm sick of those southerners in London what get all the sunny summers.Its baltic up here int North.Why can't you tree huggers and Panda lovers give it a rest. Its time we got to use our beaches up here for picnics and all that.Selfish do gooders

  • rate this
    +2

    Comment number 610.

    The issue is water is heavier then ice and drills holes who then undermine the ice base, making a exponential like increase of fresh water going into the sinking area of the Gulf Current, making possible the shutdown of thermohaline circulation scenario, and overall cooling of Europe, no matter other warming effects. This is a clear alarm, no matter the cause.

  • rate this
    0

    Comment number 609.

    597.Ceiswyn
    "Heat is energy; apply it to the atmosphere and you therefore get higher winds, which are what drives weather."

    A gross oversimplification. Temperature & pressure DIFFERENCE is what causes winds. Jupiter & Saturn both have v. high windspeeds but are far, far colder than earth.

  • rate this
    -2

    Comment number 608.

    "According to ice core records, such pronounced melting at Summit station and across the ice sheet has not occurred since 1889."

    - So then it really isn't unprecedented like the article states. I wish we would put our attention to more important environmental matters than this global warmings ride the badwagon nonsense.

  • rate this
    +2

    Comment number 607.

    594. ConnorMacLeod

    'The problem is that you cannot compare like with like. You only have averages for the Carboniferous so that's all you can work with.'

    Oh, I know; which is why gross temperature comparisons like that are so misleading. Look at the temperature changes over the comparable period of the Cenozoic :)

  • rate this
    -2

    Comment number 606.

    Global warming is but a mere trifle compared to our real problems: population vs. resources. The Earth has finite resources (someone going to argue that point?) and the population is growing exponentially (jury still out on that one?). I doubt that the effects of global warming are going to be what spells doom for us...we are teetering off the edge of a cliff created by cheap and abundant energy.

  • rate this
    -5

    Comment number 605.

    Whether we need to be worried or not, is something even scientists are not sure about.

    What I am sure about is though is government's responses: more regulation that favours large scale industry to provide the "solutions to the problem". More regulation that prohibits self-initiative and small scale inventions and developments.

    Especially the EU is good at that

  • rate this
    +4

    Comment number 604.

    579 truthhurtspainfully - Along with other people's answers, increasing the Earth's temperature will also increase the range where tropical storms can form. Just last year we saw Hurricane Irene reach Canada, and whilst it'd be completely wrong to link that one event to climate change, such storms would likely become more common if we don't do something about climate change.

  • rate this
    -2

    Comment number 603.

    Anyone know when the Jetstream last stayed this far south for so long? It wasn't around 150 years ago by any chance?

  • rate this
    -3

    Comment number 602.

    @ 590.Mightiest Martlet. Don't forget good old Harlech castle which when it was built about 1000 years ago had sea access so that they could get supplies in during a seige, but now the sea level has strangely dropped!! I'm sure there are other historical examples that can't be ignored strew all around the world!

  • rate this
    -2

    Comment number 601.

    586. Ceiswyn
    You're comparing a point temperature with a temperature averaged over, uh, 60 million years? And complaining about other people's science? Really??

    That is the whole point! Temperature measurements made over lifetimes, or thousands of lifetimes, are irrelevant on a geological scale.
    We came, we went, we weren't even noticed.

 

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