Current global warming unlike any other in the past

Washington, Oct 24 : Current global warming seems to be unlike any other in the past, which were the outcome of natural processes, says new evidence unearthed by geologists.

Sediments retrieved by University at Buffalo (UB) geologists from a remote Arctic lake are unlike those seen during previous warming episodes. Researchers found that dramatic changes began occurring in unprecedented ways after the midpoint of the 20th century.

'The sediments till the mid-20th century were not all that different from previous warming intervals,' said Jason P. Briner, assistant geology professor at the UB College of Arts and Sciences. 'But after that things really changed. And the change is unprecedented.'

The sediments are considered unique because they contain rare paleoclimate information about the past 200,000 years, providing a far longer record than most other sediments in the glaciated portion of the Arctic, which only reveals clues to the past 10,000 years.

'Since much of the Arctic was covered by big ice sheets during the Ice Age, with the most recent glaciations ending around 10,000 years ago, the lake sediment cores people get there only cover the past 10,000 years,' said Briner.

'What is unique about these sediment cores is that even though glaciers covered this lake, for various reasons they did not erode it,' said Briner, who discovered the lake in the Canadian Arctic while working on his doctoral dissertation.

'The result is that we have a really long sequence or archive of sediment that has survived arctic glaciations, and the data it contains is exceptional,' he said, according to an UB release.

Working with Briner and colleagues at UB who retrieved and analysed the sediments, study co-authors at the Universities of Colorado and Queens, have pooled their expertise to develop the most comprehensive picture of how warming variations throughout the past 2,00,000 years have altered the lake's ecology.

These results were published in the Proceedings of the National Academy of Sciences.