Centuries before fossil fuel emissions began warming the globe, Antarctica was heating up, indicates a new research published in Nature.
AP Photo/Greenpeace, Morgan
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 on 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 degrees Celsius (4.7 Fahrenheit) 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 sq km (9,500 sq miles) of ice has been lost, roughly the size of Haiti.
Burning of fossil fuels since the Industrial Revolution in the 18th century has emitted heat-trapping greenhouse gases, raising temperatures and causing floods, droughts and rising sea levels as ice melts, according to a U.N. panel of scientists.