World’s fastest-thinning glacier identified
A SLIGHT MELTING SENSATION.
A GLACIER IN Patagonia that has lost half its length in 30 years may be the fastest-thinning glacier on the planet.
Known as Hielo Patagónico Sur 12 (HPS-12 or Southern Patagonia Icefield), this huge mass of slow-moving ice is perched in the Andes mountains in Chile. Researchers reporting in the journal Nature Geoscience in September found that HPS-12 has been losing thickness and retreating inland. According to their analysis of satellite data, the glacier lost 30 metres of ice thickness each year on average between 2000 and 2008, near its terminal end. At its fastest, the thinning occurred at a rate of 44 metres per year, according to study co-author Etienne Berthier, a glaciologist at the University of Toulouse in France. The section where that thinning was recorded melted away entirely in 2018.
The Earth Observatory has released before-and-after photos showing the ice loss. One satellite shot – taken on 27 January 1985 by the Landsat 5 satellite – shows the ice of the glacier sweeping down from the mountains in the Southern Patagonia Icefield. A comparison shot taken by the Operational Land Imager on the Landsat 8 satellite in January 2019 shows a different world: the glacier hunkers into just a portion of its fjord, exposing bare rock.
The glaciers of Peru and Chile are known as ‘tropical glaciers’, a seeming oxymoron that signifies that the glaciers sit in Earth’s midsection, rather than near the poles. Tropical glaciers are retreating rapidly. Research released in 2013 found that glaciers in the Andes have lost between 30 per cent and 50 per cent of their surface area since the 1970s. These glaciers are vulnerable to warming both from above (due to air temperatures) and below (due to ocean temperatures at the glacier terminus, or the end of the glacier that is advancing or retreating).