Scientists in the United States say ice is melting in the western Antarctic at an unstoppable pace, warning that the discovery holds major consequences for global sea level rise in the coming decades.
They say the speedy melting means prior calculations of sea level rise worldwide made by the Intergovernmental Panel on Climate Change (IPCC) will have to be adjusted upwards.
“A large sector of the West Antarctic ice sheet has gone into a state of irreversible retreat. It has passed the point of no return,” said Professor Eric Rignot, an expert in Earth system science at the University of California Irvine.
AAP Newsagency reports he noted that surveys have shown there is no large hill at the back of these glaciers that could hold back the melting ice.
“It will raise sea level by 1.2 metres,” said Professor Rignot, whose paper appears in the peer-reviewed Geophysical Research Letters journal.
The paper titled “Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011, has just been published.
AAP reports a separate study published in the journal Science found that Thwaites glacier is melting fast and that its collapse could raise global sea level nearly 61 centimetres.
That study was based largely on computer modelling of the future, in addition to airborne radar measurements of the West Antarctic ice sheet.
Study author Dr Ian Joughin, a glaciologist at the University of Washington, said the process was now expected to take between 200 and 1000 years.
Results show that as the ice edge retreats into the deeper part of the bay, the ice face will become steeper and, like a towering pile of sand, the fluid glacier will become less stable and collapse out toward the sea.
“Once it really gets past this shallow part, it’s going to start to lose ice very rapidly,” Dr Joughin said in a press release.
AAP reports current projections of sea level rise, agreed upon by international surveys, do not account for the Antarctic ice sheet melting.
Professor Sridhar Anandakrishnan, an expert in geosciences at Pennsylvania State University, said studies like these would cause the United Nations to revisit its projections.
“The number for 2100 will almost certainly be revised and revised upwards, and my guess is toward what is now their upper limit of something like 90 centimetres,” said Professor Anandakrishnan.
He said that the rise in sea level was widely accepted to be a result of human-caused climate change, driven by the burning of fossil fuels.
