Summer ice is melting at a faster rate in the Antarctic Peninsular than at any time in the past 1000 years, new research has shown.
The evidence comes from a 364-metre ice core containing a record of freezing and melting over the previous millennium.
Layers of ice in the core, drilled from James Ross Island near the northern tip of the peninsular, indicate periods when summer snow on the ice cap thawed and then refroze.
By measuring the thickness of these layers, scientists were able to match the history of melting with changes in temperature.
Lead researcher Dr Nerilie Abram, from the Australian National University and British Antarctic Survey (BAS), said: "We found the coolest conditions on the Antarctic Peninsula and the lowest amount of summer melt occurred around 600 years ago. At that time, temperatures were around 1.6B0C 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 10 times as much [5%] of the annual snowfall melting each year.
"Summer melting at the ice core site today is now at a level that is higher than at any other time over the past 1000 years. And 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."
Levels of ice-melt on the Antarctic Peninsular were especially sensitive to rising temperatures during the past century. "The Antarctic Peninsular has warmed to a level where even small increases in temperature can now lead to a big increase in summer melt," Mr Abram added.
Dr Robert Mulvaney, from the BAS, led the ice core drilling expedition in 2008. He said: "Having a record of previous melt intensity for the peninsula is important because of the ice shelf loss we are now seeing in the area."
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