Sunday, November 30, 2008

Accelerated melting of continental icepacks is major reason for rise in sea level between 2003 and 2008

Science Daily: Researchers at the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (1) (CNRS/Université Toulouse 3/CNES/IRD) and at a subsidiary of CNES (CLS) (2) have discovered that the accelerated melting of continental icepacks is the major reason for the rise in sea level over the 2003 to 2008 period, something which has minimized the effect of thermal expansion of seawater. This question was resolved thanks to data from the French-American Satellite Jason-1, from two satellites of the GRACE space gravimetry mission and from the buoys of the Argo system. These results have been published online on the website of the journal Global and Planetary Change.

Between 1993 and 2003, the global mean sea level, measured very accurately by the French-American Topex/Poséidon satellites and their successor Jason-1, showed a relatively constant progression of 3 mm/yr. The last GIEC report, published in 2007, showed that more than half of this rise (approximately 1.5 mm/yr) was due to sea water expansion as it warmed up (steric contribution), while 1.2 mm/yr resulted from the reduction in mass of polar ice sheets and mountain glaciers. Since 2003 however, the situation has changed; a quite rapid rise (2.5 mm/yr) in sea water levels is still observed but, over the same period, the warming of the oceans is showing a plateau, only accounting for a rise of 0.4 mm/yr…..

NASA rendering of the JASON-2 satellite

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