The accelerating Arctic meltdown is worrying enough, but now newly published research on the health of the Antarctic ice cover is also ringing alarm bells. Is a big thaw on the way?
In a recent comment added to my October 2007 post North Polar Meltdown, Bill Alex mentioned that while the northern polar ice is disappearing fast, at the other end of the world the Antarctic ice mass has apparently been growing by some 27 gigatons a year — at least according to the latest research he’d been able to find, which was dated around the year 2000. My own quick Google search turned up a 2005 BBC News item, together with a handful of other news reports from a few years earlier, all of which agreed that (as I put it) there seems to have been a thickening of the Antarctic ice in places, while the edges are thinning and breaking off.
Now new research conducted in part by the University of Bristol and published online this week in the inaugural edition of Nature Geoscience, in a paper titled Recent Antarctic ice mass loss from radar interferometry and regional climate modelling, clarifies things for us. A press release published through EurekAlert provides a precis of the paper.
Increasing amounts of ice mass have been lost from West Antarctica and the Antarctic peninsula over the past ten years, it says. Meanwhile the ice mass in East Antarctica has been roughly stable, with neither loss nor accumulation over the past decade. This information contradicts those previous reports which implied that the overall Antarctic ice sheet was increasing its mass. If there’s been neither loss nor accumulation in East Antarctica, but an increased rate of loss in West Antarctica, then the net result must be an overall loss across the continent.
Using satellite imagery covering ten years and existing snowfall accumulation models, Professor Jonathan Bamber and his colleagues estimate that there’s been a loss of 132 billion tonnes of ice in 2006 from West Antarctica -– up from about 83 billion tonnes in 1996 -– and a loss of about 60 billion tonnes in 2006 from the Antarctic Peninsula.
Putting these figures into perspective, Professor Bamber said that four billion tons of ice is enough to provide drinking water for the whole of the UK population for one year. So nearly fifty year’s worth of the UK’s fresh water requirements drained into the ocean around the West Antarctica region during 2006 alone.
I infer from this latest paper that previous interpretations of available data — which led to the conclusion that the overall ice cover at the Antarctic had been growing due to increased snowfall caused, rather perversely, by global warming — haven’t been telling the whole story. The Antarctic ice sheet mass budget is a complex balance. Sceptics might have argued in the past that there was nothing to worry about because the increased ice loss in West Antarctica was being matched by the increased snowfall accumulation recorded in East Antarctica, but this research clearly shows that over the 10 year time period of the survey, the ice sheet as a whole was certainly losing mass, and the mass loss increased by 75% during this time.
The press release concludes that most of the mass loss is from the Amundsen Sea sector of West Antarctica and the northern tip of the Peninsula where it is driven by ongoing, pronounced glacier acceleration. In East Antarctica, the mass balance is near zero, but the thinning of its potentially vulnerable marine sectors suggests this may change in the near future.
How near? Time will tell.
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