New study finds sea level rise could be much higher by 2100

Sea level rise could be much higher than previously projected by the end of this century, according to a new study published in the journal Nature.

The study, conducted by researchers at the University of Massachusetts Amherst and Penn State University, warns that sea level could increase by up to 2 metres by 2100 if melting from the ice sheets of Antarctica and Greenland are taken into account.

The Intergovernmental Panel on Climate Change (IPCC) had previously projected sea level rise of up to 82cms by the end of the century, but this projection did not factor in a major contribution from Antarctica.

Professor Robert deConto, of the University of Massachusetts Amherst, who led the new study, said the Antarctica has the potential to contribute more than a metre of sea-level rise by the year 2100, and more than 15 metres by 2500 if atmospheric emissions continue unabated.

“To date, research into Antarctic ice sheet vulnerability has focused on the action of the ocean melting ice shelves from below,” he said. “However, it is often overlooked that the major ice shelves in the Ross and Weddell Seas and the many smaller shelves and ice tongues buttressing outlet glaciers are also vulnerable to atmospheric warming.

“In this worst case scenario, atmospheric warming, rather than ocean warming, will soon become the dominant driver of ice loss.”

The new study was prompted by studies into sea level rise during past warm periods, including the previous inter-glacial period around 125,000 years ago and earlier warm intervals such as the Pliocene epoch, around 3 million years ago.

“At a time in the past when global average temperatures were only slightly warmer than today sea levels were much higher,” said Robert deConto.“

“Melting of the smaller Greenland ice sheet can explain a fraction of this sea-level rise, but most of it must have been caused by retreat on Antarctica.

To investigate this, the researchers developed an ice-sheet climate model that includes previously under-appreciated processes that emphasize the importance of future atmospheric warming around Antarctica.

“Summer temperatures today approach or exceed 0∞ Centigrade on many ice shelves, and due to their flat surfaces near sea level, little atmospheric warming would be needed to dramatically increase the extent of surface melting and summer rainfall,” said Robert deConto.

The authors of the study found that similar conditions in the future could lead to monumental and irreversible increases in sea levels if high levels of greenhouse gas emissions were not reduced. “If global warming is not halted the rate of sea level rise would change from millimetres a year to centimetres a year,” Robert deConto said.