You’ve heard that the Arctic ice cap has shrunk, and that there are sea lanes open in the northern summer that had not been open previously, and on and so forth.

Since the start of the satellite record in 1979, scientists have observed the continued disappearance of older “multiyear” sea ice that survives more than one summer melt season. Some scientists suspected that this loss was due entirely to wind pushing the ice out of the Arctic Basin — a process that scientists refer to as “export.” In this study, Ron Kwok and Glenn Cunningham at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., used a suite of satellite data to clarify the relative role of export versus melt within the Arctic Ocean.*

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A mosaic of satellite images shows the movement of fragmented ice away from ice edges, which scientists use to track the loss of multiyear ice due to melt. Image credit: NASA Earth Observatory. Click to hugify.

ResearchBlogging.orgSome of the ice in the arctic is “mutiyear sea ice,” or essentially, a floating glacier, in that the ice consists of material built up over multiple winters and not melted away during the summer. The ice flows through the Arctic in a fairly regular pattern, with MYI observed being “exported” through various routes throughout the year. Most of this process occurs because of winds and currents, but an increasing amount seems to be accounted for by in situ melting. Scientists looked at a 17 year record of data collected by polar-observing satellites and instruments such as NASA’s Quick Scatterometer, the Ice, Cloud and land Elevation Satellite, the Advanced Microwave Scanning Radiometer, and the European Space Agency’s European (ERS)-1 and -2 satellites.

The researchers demonstrate that between 1993 and 2009 a significant amount of MYI, about 1,400 cubic kilometers, was lost due to melt. They further demonstrate that the rate of this melting has increased through time.
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…17‐year time series of annual melt areas….

One data set showed that over a 17-year period about 947,000 square kilometers, which amounts to 32% percent of the MYI that had disappeared, was lost in the Beaufort Sea due to melt. Calculations using estimate of ice thickness from 2004 to 2009 show a melt loss of 1,400 cubic kilometers (about 20% percent of the total loss by volume).

In other words, of the loss that happens every year, more is due to melt than previously thought, and this amount seems to be increasing. This has several implications. For example, ice that is blown out of the arctic sea melts in a more dispersed fashion, but extensive in situ melting means an influx of much more fresh water into the Arctic marine environment. This can influence oceanic circulation.

The last year of the study showed a dramatic drop in MYI melt. This is not because less sea ice disappeared that year, but the reasons are not explored in detail. Also, the study only accounts for roughly half of the disappearing ice, because it is not geographically comprehensive. Further studies of other regions where ice melts need to be carried out and integrated with this one.

Kwok, R., & Cunningham, G. (2010). Contribution of melt in the Beaufort Sea to the decline in Arctic multiyear sea ice coverage: 1993-2009 Geophysical Research Letters, 37 (20) DOI: 10.1029/2010GL044678

Comments

  1. #1 Jared
    November 10, 2010

    God wants us to have more beachfront property…or it could be that, just maybe, anthropogenic climate change is real. Nah, must be gawd.

  2. #2 MadScientist
    November 11, 2010

    It is very complex indeed. Over a century ago the Northwest Passage was open – for some months, in some years. It was never reliably open though, so if that particular region were to behave as it did a little over 100 years ago then I would bet it still wouldn’t be used as a commercial shipping route (not even with those huge Russian icebreakers).

  3. #3 baby rocking horse
    November 11, 2010

    The reasons for these is primarily global warming. We need to know the truth because this will have a huge impact in our lives. Although the melting of ice caps are taking a complex process, we really need to be alarmed. Many things can happen like rising of the sea levels and the changes in the salinity of water. Well, there is still a bright future for all of us.

  4. #4 IanW
    November 11, 2010

    Nice. Please let’s see more of this kind of post. This is “Science Blogs” after all!

  5. #5 MacTurk
    November 11, 2010

    “Extensive Beach Front Property” for SALE. “Baffin Bay the New Mediterranean”. “Scenic Views of the Arctic Ocean”. “Santa Claus lives Nearby”(one for the kids, no?)

    I can see the real estate agents drooling already.

  6. #6 Timberwoof
    November 12, 2010

    My roommate tells me that he used to go skydiving at the North Pole, but nobody does this any more because the ice cap is not dense enough—it does not provide a large enough, flat enough, safe enough area for parachutists to land on … any more. It’s way beyond clear that something is happening.

  7. #7 Aldis Walt
    November 20, 2010

    The melting arctic ice is really a big threat to the life on Earth. All the low lying areas may get submerged in sea water. We need to take concrete steps to check it before it is too late.
    http://illumibritereview.net/

  8. #8 Greg Laden
    November 20, 2010

    Yeah, the top of the Grand Canyon rocks are Early Permian, and of course, the canyon itself was formed by the Noachian Flood, so that must have bee the Middle Permian.

  9. #9 Scott
    January 19, 2011

    The ice caps melting has catastrophic effects on the the rest of the world. Not only could the currents that churn the oceans stop churning, (meaning, no oxygen rich water would reach the lower potion of the ocean, killing many organisms we not even know exist). The melting could change hatch time/mating time for certain fish/insects/mammals. These hatch times may be linked to times where migratory species like birds depend on those insect hatches to feed them at a specific time in order to make the journey of the migration. If the hatching happens too early, the insects will have grown and left. If the hatching happens to late, the birds have nothing to eat. Giving one example how melting of the ice caps can and will affect the globe.

Current ye@r *