South American icefields disappearing fast
Patagonian glaciers are thinning faster than Alaska’s and are boosting sea level more than would be expected from their relatively small size, according to new research. The rate of ice loss in Chile and Argentina more than doubled between 1995 and 2000.
Eric Rignot of the California Institute of Technology and colleagues from Chile studied 63 mountain icefields in Patagonia using a combination of orbital radar topography, cartographic surveys and a digital elevation model. They say in this week’s Science that a combination of higher temperatures, decreased precipitation and ice dynamics have increased the rate of loss.
Altogether, the ice loss from Patagonia’s mountain glaciers accounted for 9 per cent of the yearly rise in sea level. Alaska’s icefields accounted for 30 per cent but are five times larger, so the Patagonian contribution to the overall rise was disproportionately large.
The scientists say ice dynamics were the deciding factor. This included ice creep – thinning from longitudinal stretching – and ‘calving’, where enormous chunks of ice break off into lakewater.
Reference: Science, 302, 434 (2003)