Antarctic warming at historic rates
The summer ice melt in the Antarctic Peninsula has posted a 10-fold increase over the last 600 years, with the most rapid melting occurring in the last 50 years, according to a new collaborative research project conducted by the Australian National University (ANU)and the British Antarctic Survey (BAS).
The study saw an international science team drill a 364-metre deep ice core to measure past temperatures in the northern tip of the Antarctic Peninsula. The efforts yielded a unique and unexpected insight into ice melt in the region.
“Summer melting at the ice core site is now at a level that is higher than at any other time over the last 1,000 years,” says lead author, Dr Nerilie Abram of the ANU Research School of Earth Sciences and British Antarctic Survey.
Visible layers in the ice core indicated periods when summer snow on the ice cap thawed and then refroze. By measuring the thickness of these melt layers, the scientists were able to examine how the history of melting compared with changes in temperature at the ice core site over the last 1,000 years.
“We found that the coolest conditions on the Antarctic Peninsula and the lowest amount of summer melt occurred around 600 years ago,” said Dr Abram.
“At that time, 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%. Today, we see almost ten times as much of the annual snowfall melting each year.
“Whilst temperatures at this site increased gradually in phases over many hundreds of years, most of the intensification of melting has happened since the mid-20th century.”
“What that means is that the Antarctic Peninsula has warmed to a level where even small increases in temperature can now lead to a big increase in summer ice melt. This has important implications for ice instability and sea level rise in a warming climate.”