The glaciers of the Antarctic Peninsula down

An Anglo-American team reveals in the journal Science that the coastal glaciers of the Antarctic Peninsula have lost ground in the last fifty years.

Researchers from the British Antarctic Survey (BAS) and the US Geological Survey (USGS) analyzed more than 2000 aerial photographs taken between 1940 and 2000 as well as around 1960 satellite images dating from the 1s to the present day (via Argon , LANDSAT 2, 3, 4, 5 and 4 MSS, LANDSAT 5 and 1 TM, ERS 2 and XNUMX, RADARSAT and ASTER).

This made it possible to establish a cartography with a resolution of around thirty meters and a location precision of around 130 meters. Of the 244 glaciers studied, 87% have retreated by 600 meters on average since the 1950s (the others, irregularly distributed, having progressed only slightly), at a rate that has accelerated by 50 meters per year for the past five years.

In fact, from 1945 to 1954, 62% of these glaciers were advancing, but the trend changed from 1954 to reach a retirement rate of 75% in 2004 (these percentages based on average variations calculated with 95% of trust). The American Jane Ferrigno and her colleagues have also noted a very clear difference according to the location of the glaciers, those located in the northern part of the peninsula (warmer) being the most affected by the melting. More precisely, if we consider the isotherms at -5 ° C and -9 ° C as known in 2000, the glaciers located in the coldest zone did not vary, those located between -5 ° C and -9 ° C have decreased, while there is none in the hottest zone (above -5 ° C). This particular distribution induces a link with the atmospheric warming that this zone has experienced since 1950 (+ 2 ° C), but the team remains cautious and does not wish to make this warming the sole responsible for the retreat of the glaciers (d ' as much as a slower decline in certain areas between 1985 and 1994 does not correspond to any relative cooling). The response mechanisms of these ice monsters to climate change are indeed complex and other parameters must still be taken into account, such as ocean temperature and the amount of precipitation.

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Nonetheless, there is one clear conclusion: the retreat of the Antarctic glaciers is proving to be greater than expected.

WP 22 / 04 / 05 (Study says Antarctic glaciers are shrinking, sea levels may
climb) / 21 FT / 04 / 05 (Retreat of Antarctic ice gathers pace)

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