Friday, September 9, 2011

Inconvenient truth: Antarctica sea ice extent growing 1.43% per year

A paper published today in the Journal of Climate examines the trend of sea ice extent along the East Antarctic coast from 2000 to 2008 and finds a significant increase of 1.43% per year.

Journal of Climate 2011

East Antarctic landfast sea ice distribution and variability, 2000–2008

Alexander D. Fraser et al

Abstract: We present the first continuous, high spatio-temporal resolution time series of landfast sea ice extent along the East Antarctic coast, for the period March 2000 to December 2008. The time series was derived from consecutive 20-day cloud-free MODIS composite images. Fast ice extent across the East Antarctic coast shows a statistically-significant (1.43±0.30% yr−1) increase. Regionally, there is a strong increase in the Indian Ocean sector (20° E to 90° E, 4.07 ± 0.42% yr−1), and a non-significant decrease in the Western Pacific Ocean sector (90° E to 160° E, −0.40 ±0.37% yr−1). An apparent shift from a negative to a positive extent trend is observed in the Indian Ocean sector from 2004. This shift also coincides with a greater amount of interannual variability. No such shift in apparent trend is observed in the Western Pacific Ocean sector, where fast ice extent is typically higher and variability lower than the Indian Ocean sector. The limit to the maximum fast ice areal extent imposed by the location of grounded icebergs modulates the shape of the mean annual fast ice extent cycle, to give a broad maximum and an abrupt, relatively transient minimum. Ten distinct fast ice regimes are identified, related to variations in bathymetry and coastal configuration. Fast ice is observed to form in bays, on the windward side of large grounded icebergs, between groups of smaller grounded icebergs, between promontories, and upwind of coastal features (e.g., glacier tongues). Analysis of the timing of of fast ice maxima and minima is also presented and compared with overall sea ice maxima/minima timing.

4 comments:

  1. This isn't news and here's an explanation from a couple years ago:
    http://www.newscientist.com/article/dn16988-why-antarctic-ice-is-growing-despite-global-warming.html

    But it's not all bad as we'll have lots of crab for dinner:
    http://www.newscientist.com/article/dn20876-giant-red-crabs-invade-the-antarctic-abyss.html

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  2. Oh, that old chestnut again.

    The hypothesis that increased Antarctic sea extent is due to the "the ozone hole" is just that, an untested hypothesis.

    Come back when you have found a study that correlates observed sea-ice extent with observed ozone levels.

    A more interesting theory, one actually backed up by direct data shows that a correlation exists between temperature changes in the Arctic and Antarctic.

    Researchers on the European Project for Ice Coring in Antarctica (EPICA) have used ice-cores from Antarctica and Greenland to study 150,000 years of climate history which reveal both regions are connected by ocean currents in a see-saw climate relationship.

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  3. Senator Inhofe mentions this study on the Senate floor:

    http://epw.senate.gov/public/index.cfm?FuseAction=Minority.Speeches&ContentRecord_id=e841f28c-802a-23ad-42b3-7c8aa4ac8b1b

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  4. So the Antarctic sea ice extent is growing. And the Arctic sea ice extent is shrinking. Taking the two together, global sea ice extent is about average.

    ReplyDelete

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