Arctic sea ice now lowest on satellite record

Tuesday 28 August 2012, 16:20

Paul Hudson Paul Hudson

The extent of sea ice in the Arctic region has dropped sharply in the last few months.

Only in April, Arctic sea ice had staged an impressive recovery and was close to the 1979-2012 average, reaching levels not seen in April for over 10 years.

But yesterday, the National Snow and Ice data centre reported that the extent of Arctic sea ice shrank to 1.58 million square miles, breaking the previous record set in the summer of 2007, based on satellite data which was first gathered in 1979.

Usually the minimum ice extent is not reached until September, suggesting that further ice loss is likely.

Including this year, the six lowest ice extents in the satellite record have occurred in the last six years.

And most scientists, whilst accepting that some of the decline in sea ice is likely to be down to natural factors such as prevailing weather conditions and natural ocean cycles, believe a substantial proportion is down to man-made influences such as global warming due to higher greenhouse gases in the atmosphere.

The big worry is that continued melting sea ice would cause serious feedback mechanisms to kick-in.

Firstly with less sea ice to reflect incoming solar radiation back into space, the sea will warm more quickly than would otherwise be the case, speeding up global warming.

And secondly, natural methane trapped under the sea-bed by permafrost could be released. Methane is a much more powerful greenhouse gas than carbon dioxide, and would also accelerate global warming.

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  • rate this

    Comment number 1.

    "Only in April, Arctic sea ice had staged an impressive recovery and was close to the 1979-2012 average"

    That was purely sea ice extent. Volumes have been steadily going down to the point that some researches refer to much of the 'recovered' ice as rotten or a slushie. That accounts somewhat for the steep decline from near average extent to record low.

  • rate this

    Comment number 2.

    Yes, and crucially very different from the Little Ice Age (which certain groups seem convinced will re occur today) when arctic ice extent increased substantially - according to past research.

  • rate this

    Comment number 3.

    We are currently in an inter-glacial period between ice ages.
    During such periods, the Earth is ice-free, even at the poles.
    About 12500 years ago, Britain was covered in an ice sheet, since when
    the extent of the ice has been declining.
    Is it surprising that the ice is still declining?
    Would it be a good thing if the ice was extending?

  • rate this

    Comment number 4.

    The LIA is interesting. Some say we are still exiting from the LIA so the warming and ice loss are due to that. Others are saying we are entering a LIA and cooling has started. Both can't be right (though both could have wrong conclusions!).

  • rate this

    Comment number 5.

    A quick word on the satellite record

    According to the final report of working group 1 of the intergovernment panel on climate change sea-ice extent has been measured by satellits since the early 1970s

    "Especialy importantly, satellite observations have been used to map sea-ice extent routinley since the early 1970s. The American Navy Joint Ice Centre has produced weekly charts which have been digitised by NOAA"

    Page 224

  • rate this

    Comment number 6.

    My 1950's encyclopedia tells me that the Russian ports along the coast of Siberia were building a roaring trade in the early part of the 20th century transporting mainly flax along the northern sea board. Arctic ice extent was lower than today and the ships sailed for many months during the year. As I personally recall, during the 1950's the ice returned with vengeance and all the ports closed and trade ceased completely by the end of the 50's.

    It's only in the past few years that this sea route has become navigable again. There's also piles of other historical evidence that ice was low then than today.

    So no problem just cyclic and boy I’d not like to see it going in the other direction!!

  • rate this

    Comment number 7.

    The NSIDC have good shipping/photos/naval records back to the 1950's and satellite data from the late 1970's.

    Come on, you'll be mentioning submarines next...

  • rate this

    Comment number 8.

    john_cogger @7 you say:

    "The NSIDC have good shipping/photos/naval records back to the 1950's"

    Agreed. The 50's was when I remember the ice returned with vengence and the shipping trade decreased and the ports shut down. I was talking the previous 50 years when it was in its heyday. Check it out for yourself.

    Your chart starts at the high point of last century. Makes sense.

  • rate this

    Comment number 9.

    Thanks John for the NSIDC sea ice data back to the 1950's
    Ofcourse temperature data up in the Arctic has been available for much longer.
    Climate4you show this graph based on hadcrut3 data

    The temperatures back in 1935-45 were just as high as today
    First commercial crossing of NW passage was 1942
    Look at that temperature rise from 1915 to 1920's!
    No rise in CO2 about then

  • rate this

    Comment number 10.

    How long has satellite information been available, more fear, false evidence appearing real. I would be more concerned about the next 30/40 years, when winters become much colder and food production slows. I wonder what caused the dip in world temperatures after the 2nd world war, when industrial production went through the roof.

  • rate this

    Comment number 11.

    Meanwhile, the HadCRUT3 anomaly figure for July has just been published at 0.446c, slightly down on last month's 0.477c, while the N.H. figure was up from 0.661c to 0.687c and the S.H. was down from 0.293c to 0.205c.
    All of the major global & S.H. anomaly figures showed slight falls, while only HadCRUT3 showed an increase in the N.H.
    In reality, global temperatures have been fairly stable since April and based on the latest AQUA CH5 temperature figures, should remain so in August, possibly showing slight increases over the July figures, i.e. returning to approximately the same levels as in June.

  • rate this

    Comment number 12.

    Graph here suggests sea ice extent in August 1938 was substantially greater than in August 2012

  • rate this

    Comment number 13.

    @9 Neilhamp

    Not sure if the St Roch in 1942 was a commercial vessel but it took 28 months to make the journey. Many times the vessel was frozen in ice.

  • rate this

    Comment number 14.

    The ice extent was also probably much greater in 10000 b.c.

  • rate this

    Comment number 15.

    This report, from NSIDC satellites, is not unexpected given the fact that the NSIDC reported the data from their old satellites which use microwave measurements. These old satellites have a problem with detector degradation that is well documented. There was also a severe storm in early August which broke the ice into pieces and the microwave detectors on these old satellites cannot detect broken ice accurately. The data from these satellites is not reliable. The latest satellites, used by NSIDC and NASA, which do not have the same problems, show ice coverage some 30% above the 2007 ''lowest ever'' figure. But this data was not released to the media presumably to continue the alarmism of AGW.
    Arctic climate cycles are approximately 80 years in length. Satellite observation has been in situ for 33 years, not even half the normal cycle, so why do we attach such importance to this iffy data set from degraded satelites?

  • rate this

    Comment number 16.

    I am wondering why, given that Antarctic ice is still expanding, that this information has not been reported? Recently reports that 25 states of the USA had record(?) temperatures again failed to note that the other 25 states experienced ''lower than average'' temperatures. I might add that the highest ever temperatures in the US were during the 1930's.

  • rate this

    Comment number 17.

    John Marshall wrote:
    "I am wondering why, given that Antarctic ice is still expanding, that this information has not been reported?"

    Probably because the increase in Antarctic ice is what many climate models predicted as an initial sign of global warming. Hansen mentions increased snowfall and net net ice sheet growth in a paper over 30 years ago;

  • rate this

    Comment number 18.

    John Marshall it is nice to see somebody on here with common sense. Too many have watched the day after tomorrow and believed it was true, I am sure that is where the climate modellers get their data from. The met office can't even get a daily forecast correct, they put that many different outcomes out, they have to be eventually right.

  • rate this

    Comment number 19.

    @18 Tim

    The info on the arctic isn't a model. Its now, it's data, it's whats happening right now.

    With cold winters being linked to the drop in ice in the arctic, I'd of thought you'd be happy. You might get the foot deep snow you so often predict.

  • rate this

    Comment number 20.

    #17. - Lazarus wrote:
    Probably because the increase in Antarctic ice is what many climate models predicted as an initial sign of global warming. Hansen mentions increased snowfall and net net ice sheet growth in a paper over 30 years ago;"

    He may mention it, but from this quote from the blog, he doesn't seem to be coming down one way or another.
    “Melting of the world’s ice sheets is another possible effect of CO2 warming.
    If they melted entirely, sea level would rise ~ 70 m. However, their natural response time is thousands of years, and it is not certain whether CO2 warming will cause the ice sheets to shrink or grow.
    For example, if the ocean warms but the air above the ice sheets remains below freezing, the effect could be increased snowfall, net ice sheet growth, and thus lowering of sea level.”
    I am not sure that this is predicting an increase in Antarctic ice at all, more outlining the possibility that global ice "could" be net (global) ice sheet growth.
    Also, it associates such growth in ice sheets with lowering sea levels, which afaik isn't happening.
    What we seem to be getting is a decline in sea ice in the Arctic and an incease in the Antarctic.
    Is it snowing less in the Arctic and more in the Antarctic?


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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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