Disappearing snow increases risk of collapsing ice shelves in Antarctica
Global warming will threaten more ice shelves in the next 200 years
A number of floating ice shelves in Antarctica is at risk to disappear entirely in the next 200 years, as global warming reduces their snow cover. Their collapse would enhance the discharge of ice into the oceans and increase the rate at which sea level rises. A rapid reduction of greenhouse gas emissions could save a number of these ice shelves, researchers at Utrecht 木瓜福利影视 say in an article that was published 30 January in the Journal of Glaciology.
Back in 1995 and 2002, two floating ice shelves in the north of the Antarctic Peninsula suddenly collapsed in a matter of weeks. "A spectacular event, especially when you imagine that these ice shelves are several hundreds of metres thick, and have been in place for over 10,000 years", according to the paper's lead author dr. Peter Kuipers Munneke (Utrecht 木瓜福利影视).
The team of researchers suspected that the disappearing snow layer on top of the ice shelves is an important precursor for ice-shelf collapse. Their calculations confirm this hypothesis, and show that many more ice shelves could disappear in the next 200 years.
Meltwater lakes
As long as the snow layer is sufficiently thick and cold, all meltwater can sink into the snow and refreeze. But in a warmer climate, the amount of meltwater increases, and the snow layers become thinner. As a result, meltwater can no longer refreeze and forms large lakes on the surface of the ice shelves. The water drains through cracks and faults, causing them to widen until they become so wide and deep that the entire ice shelf disintegrates.After their collapse, ice shelves can no longer provide resistance to the flow of the glaciers previously feeding them. As a result, the glacier flow accelerates significantly, contributing to a faster sea-level rise.
Two scenarios
The researchers performed calculations that show how this process evolves over the next 200 years. They used two different climate scenarios. "If we continue to burn fossil fuels at the current rate, almost all ice shelves in the Antarctic Peninsula will be under threat of collapse in the next 200 years. Only the two largest ones seem to be safe. Even in the much colder eastern part of Antarctica, some ice shelves could disintegrate. If we manage to keep global warming below the European Union target of 2掳C, more than half of the ice shelves could be saved", according to Kuipers Munneke.
Publication
'Firn air depletion as a precursor for Antarctic ice-shelf Collapse',Peter Kuipers Munneke1, Stefan Ligtenberg1, Michiel van den Broeke1, David Vaughan
Journal of Glaciology, 30 January 2014.
1 Affiliated with Utrecht 木瓜福利影视, Institute for Marine and Atmospheric research Utrecht (IMAU)
This research is funded by the Netherlands Polar Programme of Netherlands Organization for Scientific Research, and the European research project Ice2Sea.