Melting drainage glaciers could have big impact on massive interior ice sheets
By Summit Voice
SUMMIT COUNTY — Climbing temperatures in the Southern Ocean continue to nibble away at the Antarctic ice sheet, as the drainage glaciers at the edge of the frozen continent speed up.
Those changes could have a significant effect on the massive interior ice fields, according to researchers with the University of New South Wales Climate Change Research Centre.
“It has long been known that narrow glaciers on the edge of the Antarctica act as discrete arteries termed ice streams, draining the interior of the ice sheet,” said Dr. Chris Fogwill, author of a new study published in the journal Proceedings of the National Academy of Sciences.
“However, our results have confirmed recent observations suggesting that ocean warming can trigger increased flow of ice through these narrow corridors. This can cause inland sectors of the ice-sheet - some larger than the state of Victoria – to become thinner and flow faster.”
The modeling showed that glacier acceleration triggered by ocean warming is relatively localized, but the extent of the resultant ice-sheet thinning is far more widespread. The glaciers that responded most rapidly to warming oceans were found in the Weddell Sea, the Admundsen Sea, the central Ross Sea and in the Amery Trough.
The finding is important because of the enormous scale and potential impact the Antarctic ice sheets could have on sea-level rise if they shift rapidly, said Fogwill.
“To get a sense of the scale, the Antarctic ice sheet is 3km deep; three times the height of the Blue Mountains in many areas. And it extends across an area that is equivalent to the distance between Perth and Sydney.
“Despite its potential impact, Antarctica’s effect on future sea level was not fully included in the last IPCC report because there was insufficient information about the behaviour of the ice sheet. This research changes that. This new, high-resolution modelling approach will be critical to improving future predictions of Antarctica’s contribution to sea level over the coming century and beyond,” he said.
The researchers, led by Dr Nicholas Golledge from Victoria University of Wellington, New Zealand, tested high-resolution model simulations against reconstructions of the Antarctic ice sheet from 20,000 years ago, during the last glacial maximum.
They used a new model, capable of resolving responses to ice-streams and other fine- scale dynamic features that interact over the entire ice sheet. This had not previously been possible with existing models. They then used this data to analyze the effects of a warming ocean over time.