Global sea levels could rise as much as two metres by 2100, experts said in a new study published Monday.
That's more than twice the highest estimate given by the International Panel on Climate Change (IPCC) in their bombshell 2013 report that said sea levels would rise by between 52 and 98 centimetres by 2100.
A sea level rise of two metres would displace over 180 million people, the new study said, and "would clearly have profound consequences for humanity."
Without drastic coastal reinforcement strategies, a rise of this magnitude would see parts of London under water and the northern coast of the Netherlands would be severely altered. European coasts would be prone to much higher levels of flooding. Perhaps predictably, Venice would be greatly submerged.
The study, published in the journal Proceedings of the National Academy of Sciences of the United States of America was based on analysis from an international team of scientists and 22 ice sheet experts led by the University of Bristol in the UK.
It provides a new look into the potential impact of climate change and its consequences on rising sea level, a notoriously difficult variable to measure.
"Such a rise in global sea level could result in land loss of 1.79 million km2, including critical regions of food production, and potential displacement of up to 187 million people," said lead author Jonathan Bamber from the University of Bristol's School of Geographical Sciences. Watch our interview with Bamber in the player above.
Further afield, a rise of this nature could see the disappearance of a large swathe of southern Florida and disaster for much of the Caribbean. Images from Climate Central allow us to see the potential damage to coastlines worldwide.
The experts' worst-case prediction of a two-metre sea level rise follows a "business as usual" scenario in which the climate emergency continues on its current path without significant efforts to stall rising global temperature.
A difficult task at hand
There is uncertainty about how the Greenland and Antarctic ice sheets will melt and affect sea level rise. The study authors analysed several different scenarios.
In the optimistic model in which the Earth warms two degrees Celsius consistent with the Paris agreement, sea level rise will obtain a median of 26 cm. But in the scenario consistent with current trends, temperatures rising 5 degrees Celsius would create sea level rise between 51 and 178 cm, the report said.
This, in addition to glacier contributions and thermal expansion, would result in a two-metre sea level rise.
By 2200, the situation is even more grave, given a risk of further ice melting in West and East Antarctica.
Maps reflecting possible scenarios of sea level rise paint a bleak picture. In a two-metre sea level rise scenario, most maps show the coastline of the Netherlands completely submerged.
But with information about rising sea levels, countries can better prepare for it.
"It is hoped that the results can provide decision-makers with greater awareness of potential high-end SLR, which is crucial for robust decision making," co-author Willy Aspinall, from the University of Bristol's School of Earth Sciences said.
"The Netherlands is already below sea level for a large part, but our Dikes and Pumping stations make sure our land does not flood," Jeroen Aerts, director of the Institute for Environmental Studies at the Vrije Universiteit Amsterdam told Euronews.
As sea levels rise, "we have to elevate our levees again, but we are doing that for the last 1000 years," he said.
The experts say that it's a low probability that sea levels would hit the upper range estimate of two metres, but, they said, it's a possibility bad enough that coastal communities certainly should not rule it out.