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Showing posts with label ice core. Show all posts
Showing posts with label ice core. Show all posts

Monday, April 15, 2013

Antarctic Peninsula: nonlinear intensification of melt unprecedented in last 1000 years

This study analysing an Antarctic Peninsula ice core from James Ross island has determined that there has been a ten fold increase in melt intensity over the last 600 years. I reported recently that the Antarctic Peninsula summer melt season prolonged by global warming according to research from the British Antarctic Survey.

"The warming has occurred in progressive phases since about AD 1460, but intensification of melt is nonlinear, and has largely occurred since the mid-twentieth century. Summer melting is now at a level that is unprecedented over the past 1,000 years. We conclude that ice on the Antarctic Peninsula is now particularly susceptible to rapid increases in melting and loss in response to relatively small increases in mean temperature." concludes the study.

The information comes from a 364 meter ice core drilled by a joint UK and French research team on James Ross Island, near the northern tip of the Antarctic Peninsula. Analysis of the ice core can reveal past temperature changes as well as revealing past extent of ice melt events.

West Antarctic Ice Cores find changes at upper bound of normal

A new ice core study from the West Antarctic Ice Sheet (WAIS) concludes that current dramatic and unusual warming changes on the West Antarctic Ice Sheet may still be in the bounds of natural decadal variability.

In other words, the warming trend signal is still not strong enough to distinguish it above the noise of peak warming periods in multi-decade long cycles involving the Tropical Pacific atmospheric circulation, sea surface temperatures and the El NiƱo (ENSO) cycle.

While acknowledging the rapid warming over the West Antarctic Ice Sheet the authors conclude that "It is unknown whether these changes are part of a longer-term trend."

Related: Global warming in Antarctica: Thwaites and Pine Island Glaciers | Waking the giant: Global Warming in the Weddell Sea | Southern Ocean warming impact on Antarctic Ice Sheet and global sea level | Antarctic Paradox: ocean warming melting ice shelves causing sea ice expansion