Temperatures in the Antarctic Peninsula started rising naturally 600 years ago, long before man-made climate changes further increased them, scientists said in a study Wednesday that helps explain the recent collapses of vast ice shelves.
The study, reconstructing ancient temperatures to understand a region that is warming faster than anywhere else in the southern hemisphere, said a current warming rate of 2.6 C per century was "unusual" but not unprecedented.
"By the time the unusual recent warming began, the Antarctic Peninsula ice shelves were already poised for the dramatic break-ups observed from the 1990s onwards," said the British Antarctic Survey, which led the study published in the journal Nature.
A warming trend caused by natural variations, perhaps affecting winds and ocean currents, began 600 years ago and made ice shelves - tracts of ice floating on the ocean around the peninsula - vulnerable to even faster warming since 1920.
Several ice shelves around the peninsula have collapsed in recent years, including the Larsen A and B shelves and the Wilkins. About 25,000 square kilometres of ice has been lost, an area roughly the size of Haiti.
