'Irreversible' melting of Antarctic
Two separate papers, published in the peer-reviewed journals Science and Geophysical Research Letters, have found that unstoppable melting is happening in the West Antarctic Ice Sheet. This would drive sea levels up by an extra 4m, over and above any other increase thanks to global warming and the melting of other glaciers.
This ice sheet has kept its ice for the last 100 000 years, although the entire sheet is thought to have melted 600 000 years ago. This single act drove global sea levels up by several metres. But the papers said the rate at which ice is melting on the sheets has increased by 77% in the last four decades.
The melting of the sheets is nothing new. They have been shrinking and expanding throughout the planet’s history. With each change came huge rises and drops in global sea levels – ice sheets are the biggest driver of sea levels.
We are currently between ice ages, so sea levels are high and the ice sheets have shrunk. But they are still holding massive reserves of water, which would rapidly drive up sea levels if they melted.
The intergovernmental panel on climate change said in its recent report that sea levels had risen by a few centimetres in the last few decades, thanks to human-driven global warming. It predicted up to a 1m rise in sea levels across the world by the end of this century, although this did not include the new numbers from Antarctica. The process would be “irreversible”, it said.
While world governments are trying to negotiate an agreement to lower carbon emissions, with the express aim of lowering the impact of climate change, the research papers found that this would not help with these ice sheets. Researchers at Nasa, who were behind the one paper, said the collapse of major glaciers now “appears unstoppable”.
The process had already started. “The simulations indicate that early-stage collapse has begun,” said the Nasa paper.
The problematic ice sheets were the ones on the edge of the West Antarctic Ice Sheet. These were attached to the ground below, creating lynchpins. This stopped ice inside the Antarctic from melting and flowing into the ocean. But they were being eroded by warming ocean water – most of the heat from global warming is being stored in the oceans.
The glaciers would only fully collapse in the next 500 years to 1 000 years, but nothing could be done to avert it. The United Nations said that with just a 1m rise in sea levels, there would be a humanitarian crisis. People living in coastal areas – most of the world’s capitals are by the sea – would be displaced and have to move further inland.
At the moment the Antarctic is actually increasing in overall size, with the Arctic in the north pole reaching its lowest levels in recorded history in each summer in the last four years. The Arctic is predicted to be ice-free every summer by the middle of this century.
The National Academy of Sciences in the United States said if all the world’s ice sheets melted, sea levels would rise by over 60m.
And all of this means is that living by the coast might be something people who now stay dozens of kilometres away from the beach will be able to enjoy in the coming centuries.