In its fifth assessment report, the Intergovernmental Panel on Climate Change (IPCC) predicted between 52 and 98 centimeters (approximately 1.7 to 3.2 feet) of sea level rise by 2100. But the new study, published in the Proceedings of the National Academy of Sciences Monday, put the range at 62 to 238 centimeters (approximately two to 7.8 feet).
“We should not rule out a sea-level rise of over two meters (6.5 feet) if we continue along a business-as-usual emissions trajectory,” study lead author of the University of Bristol Jonathan Bamber said, according to USA Today.
The upper estimate is what would happen if temperatures rose 5 degrees Celsius by the century’s end and has about a 5 percent chance of occurring. But Bamber said it was still worth taking seriously.
“If I said to you that there was a one in 20 chance that if you crossed the road you would be squashed you wouldn’t go near it,” Bamber told BBC News. “Even a one percent probability means that a one in a hundred year flood is something that could happen in your lifetime. I think that a five percent probability, crikey — I think that’s a serious risk.”
Such a rise in sea levels would have devastating consequences. It would swallow 1.79 million square kilometers (approximately 700,000 square miles) of land, an area roughly the size of Libya, or three times the size of California, according to USA Today. The inundation would threaten important agricultural areas like the Nile delta, parts of Bangladesh and major cities like New York, London and Shanghai, BBC News said. It would also swamp Pacific island nations and displace as many as 187 million people, Bamber told New Scientist. Bamber put it in perspective for BBC News by saying that the Syrian refugee crisis had seen only one million displaced into Europe.
“A sea-level rise of this magnitude would clearly have profound consequences for humanity,” Bamber said, as USA Today reported.
Recent studies based on satellite data have shown that glaciers in both the Arctic and Antarctic are melting at accelerating rates. A theory has also emerged that ice cliffs in Antarctica might collapse as the ice sheets that support them melt.
Bamber told New Scientist there was still time to avert catastrophe.
“We can make some choices but we have to make them very soon,” he said.