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 a hundred satellite images dating from the 1960s to the present day (via Argon , LANDSAT 1, 2, 3, 4 and 5 MSS, LANDSAT 4 and 5 TM, ERS 1 and 2, RADARSAT and ASTER).

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

In fact, from 1945 to 1954, 62% of these glaciers were increasing, 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 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 change, those located between -5 ° C and -9 ° C have decreased, while there is none in the hottest area (above -5 ° C). This particular distribution induces a link with the atmospheric warming that this area has known since 1950 (+ 2 ° C), but the team remains cautious and does not wish to make this warming solely responsible for the retreat of the glaciers (of as much as a slowing of the 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 the temperature of the oceans and the amount of precipitation.

Read also: Peace by water

There remains a clear conclusion: the retreat of the Antarctic glaciers turns out to be greater than what was estimated.

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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