The South Pole is melting too
Published 23rd November 2009 - 32 comments - 5411 views -
The ice masses on Antarctica are melting into the oceans a recent study confirms. For the last seven years the rate of loss has been approximately 190 gigatonnes each year. And no, it didn't stall, it has increased.
The data is quite fresh: published in Nature Geoscience on 22nd of November 2009. And it agrees with another recent study of entirely different methodology which in 2008 estimated a loss of ice at about 196 ± 92 Gt yr-1.
A GRACEful study?
The research is based on measurements from the Gravity Recovery And Climate Experiment (GRACE) [project website, Wikipedia]. It's data from a satellite measuring gravity, hence indirectly mass. 79 monthly samples covering April 2002 to January 2009 have been used. Those measurements have been “cleaned” for noise such as atmospheric pressure and ocanic signals to produce accurate estimates for ice mass.
More precisely, the result is ice loss of about 190 ± 77 Gt yr-1. So it's a bit more precise than the 2008 study. Both studies vary in their estimates of regional changes. Apparently, the Amundsen Sea Embayment is losing the most ice: about 110 Gt yr-1. And at an accelerating rate during 2006-2009.
Less room for scepticism
That's yet another nail for the coffin of climate change scepticism. Fair enough: it hasn't been very obvious that the South Pole was melting. Three main explanations for this are the following [2, 3]:
Ozone hole has had a cooling effect of 2 to 6 degrees; incl. increases in winter storms.
Increased precipitation freshens cold surface water causing less mix with warmer water currents below hence colder water near the ice.
More snow-ice created (due to both precipitation and storms).
Perhaps a fourth reason being wishful thinking by the sceptics? The mixed message from the south has led to claims of Antarctica disproving global warming [3, 4]. The GRACE studies does show much variability across the continent, including local ice mass increases.
“Antarctica may soon be contributing significantly more to global sea-level rise.”
 (Source unless otherwise noted)
Chen, J., Wilson, C., Blankenship, D., & Tapley, B. (2009). Accelerated Antarctic ice loss from satellite gravity measurements Nature Geoscience DOI: 10.1038/NGEO694
This post was chosen as an Editor's Selection for ResearchBlogging.org
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