In many climate models and scientists’ theories the West Antarctic ice sheet is expected to melt over the coming hundreds of years and raise the sea levels. Much of this is based on the theory that during the last interglacial period the ice sheet must have melted in order to raise the sea levels as much as they had been. However new research suggests that the West Antarctic ice sheet may be more stable than had been previously realised.
Dr Chris Fogwill, from the University of Exeter’s Geography department in the College of Life and Environmental Sciences, has been carrying out research into the stability of the West Antarctic ice sheet by using cosmogenic dating, a form of dating which looks at the cosmic radiation levels in exposed rocks.
“The debate on the ice-sheet focuses around the Earth’s past climate. Evidence suggests our climate has warmed before and about 125,000 years ago there was an ‘interglacial period’ when global temperatures were about 2°C warmer than they are today,” explained Fogwill.
“Some models of that past climate suggest sea-levels were much higher during that time than they are now, and some of that water would have to have come from this giant freshwater body of ice – suggesting the ice-sheet is vulnerable to melting at warmer global temperatures.”
“However, we found evidence which suggests the ice-sheet has been around for at least 200,000 years, meaning that it has survived at least one warm period and is more resilient than thought.”
Cosmogenic dating relies on measuring the radiation in objects left over from the Big Bang, but this radiation only enters an object when it is exposed, in other words, when it is not covered by masses of ice. By studying bare rock along the Heritage range of mountains near the central dome of the West Antarctic ice sheet, they found that the rock had probably been covered by ice for at least 200,000 years, a period of time longer than previously thought.
This means that it is possible the West Antarctic ice sheet survived during the last interglacial warming period – which is theorized to have had temperatures 2°C warmer than today – intact.
“This research doesn’t provide conclusive evidence,” Dr Fogwill added, “but it definitely provides us with a solid theory. There is evidence from other studies which suggests the ice-sheet isn’t as resilient, so this will remain an area of uncertainty for now.”