The ice sheet has been retreating for the last few thousand years, but we think the end of this retreat has come

Dr Ian Joughin

The long-term future of the West Antarctic Ice Sheet (WAIS) has been the focus of much concern. While the East Antarctic Ice Sheet is considered relatively safe, there have been fears that climate change could cause the WAIS to disintegrate, raising global sea levels by as much as five metres.

That could have a catastrophic effect on coastal communities.

Most researchers are agreed that the West Antarctic Ice Sheet has been retreating over the last 10,000 years, but the new findings, published in the journal Science, could be evidence that that this trend is about to be reversed.

Still some concern

Dr Ian Joughin, of the American space agency's (Nasa) Jet Propulsion Laboratory, and Slawed Tulaczyk, of the University of California at Santa Cruz, say they have found "strong evidence" that the ice sheet in the Ross Sea area is growing, by 26.8 gigatons per year.

Most of the growth is on an ice sheet called ice Stream C.

"The ice sheet has been retreating for the last few thousand years, but we think the end of this retreat has come," says Dr Joughin. But he said it would be a mistake to assume any threat of the ice sheet collapsing was completely removed.

"Some of the concern about the collapse of the West Antarctic Ice Sheet is lessened, but I hesitate to say we can stop worrying about it."

Difficult to predict

He said the research only covered a relatively small area, over a short period of time and it was possible that what they were detecting was a minor fluctuation.

He pointed out that there were other areas in West Antarctica where the ice was thinning significantly, such as the Pine Island Glacier and the Thwaites Glacier.

Dr Duncan Whingam, of University College London, UK, who is studying these glaciers, said the new research was "very interesting" and illustrated how the picture regarding the ice in West Antarctica was becoming "increasingly complex".

"The research summarises a picture that's been emerging for the last 10 years. West Antarctica, it's clear, is not behaving in a unitary way. It's harder than ever to predict how this area of Antarctica is going to evolve."