The Sea Is Rising at Such a Catastrophic Rate That We Could Lose 700,000 Square Miles of Land, Displacing 187 Million People

greenland, ice sheet, NASA
Sea ice is seen from NASA's Operation IceBridge research aircraft along the Upper Baffin Bay coast above Greenland on March 27, 2017. Greenland's ice sheet is retreating due to warming temperatures. Mario Tama/Getty Images

Sea level rise could exceed 2 meters (6.6 feet) by 2100, endangering coastal communities and ecosystems around the world, according to research published in the journal Proceedings of the National Academy of Sciences.

As the Earth's climate warms, melting ice sheets in Greenland and the Antarctic are expected to lead to an increase in global sea levels. When devising strategies to mitigate and plan for the potential impacts of this, scientists rely on projections that tend to be based on numerical modeling. However, such projections are difficult to produce because the evolution of the ice sheets and how they will respond to climate change is unclear.

To try and get a more realistic picture of future sea level rise, Jonathan Bamber from Britain's University of Bristol and his colleagues used a technique called structured expert judgment (SEJ.) This involved asking 22 ice sheet experts to estimate plausible ranges for future SLR as a result of melting ice in Greenland and the Antarctic under both low and high global temperature rise scenarios.

"SEJ provides a formal approach for estimating uncertain quantities based on current scientific understanding and can be useful for estimating quantities that are difficult to model," Bamber said in a statement.

"Projections of total global SLR using this method yielded a small but meaningful probability of SLR exceeding two meters by the year 2100 under the high temperature scenario, roughly equivalent to 'business as usual,' well above the 'likely' upper limit presented in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)," he said.

According to Bamber, such a rise in sea levels would have significant impacts on coastal communities. Therefore, he said, they should take into account the potential for a 2-meter spike when developing strategies to mitigating risks.

"Such a rise in global sea level could result in land loss of 1.79 million square kilometers [around 691,000 square miles], including critical regions of food production, and potential displacement of up to 187 million people," he said. "An SLR of this magnitude would clearly have profound consequences for humanity."

Willy Aspinall, another author of the University of Bristol study, said he hoped the results could make decision-makers aware of the potential for higher SLR than expected.

"Limiting attention to the 'likely' range, as was the case in the IPCC Fifth Assessment Report, may be misleading and will likely lead to a poor evaluation of the true risks," he said.