James Ross Island, near the top of the Antarctic Peninsula. (Photo Credit: NASA Photo by: Jim Ross)
Antarctic summer 10-fold ice melt increase: study
Tuesday, April 16, 2013, 02:20 (GMT + 9)
Summer ice melting has intensified almost 10-fold in the Antarctic Peninsula in the last 600 years, according to a new 1,000-year climate reconstruction, which shows that levels of ice melt on the Antarctic Peninsula have been especially sensitive to increasing temperature in the last century.
The research was carried out by experts from the Australian National University (ANU) and the British Antarctic Survey (BAS) and was published this week in the journal Nature Geoscience, helping make more accurate projections about the direct and indirect effect of Antarctica’s ice shelves and glaciers on global sea level rise and about the fact that summer ice melt hampers the stability of Antarctic ice shelves and glaciers.
The measuring started in 2008 when a UK-French science team drilled a 364-m-long ice core from James Ross Island, near the top of the Antarctic Peninsula, to measure past temperatures there -- and realized that this ice core could also offer insight into regional ice melt.
As visible layers in the ice core pointed to periods when summer snow on the ice cap thawed and then refroze, measuring the thickness of these melt layers allowed the scientists to examine how the history of melting fared against changes in temperature at the ice core site over the last 1,000 years.
Lead author Dr Nerilie Abram of the ANU and BAS said the coolest conditions on the Antarctic Peninsula and the lowest amount of summer melt took place around 600 years ago, when temperatures were around 1.6 °C lower than those recorded in the late 20th Century and the amount of annual snowfall that melted and refroze was about 0.5 per cent.
Today, in contrast, we see almost 10 times as much (5 per cent) of the annual snowfall melting each summer.
Now, the Antarctic Peninsula has warmed to a level where even small increases in temperature can bring a big increase in summer ice melt, Abram added.
Dr Robert Mulvaney from the BAS, co-author, led the ice core drilling expedition.
“Having a record of previous melt intensity for the Peninsula is particularly important because of the glacier retreat and ice shelf loss we are now seeing in the area. Summer ice melt is a key process that is thought to have weakened ice shelves along the Antarctic Peninsula leading to a succession of dramatic collapses, as well as speeding up glacier ice loss across the region over the last 50 years,” he said.
By Natalia Real