Sea levels around the world are expected to rise by more than 2 meters (6.6 feet) by the end of the century, experts warned.
In a study featured in the journal Proceedings of the U.S. National Academy of Sciences, Prof. Jonathan Bamber, an expert on physical geography from the University of Bristol, and his colleagues examined the effects of climate change on global sea levels over the next few decades.
If nothing is done about current carbon emission levels, world temperatures would rise by as much as 5 degrees Celsius (9 degrees Fahrenheit).
This global warming will cause ice sheets in Antarctica and Greenland to melt at an alarmingly fast rate, resulting in sea levels that will far exceed the upper limit set in the United Nation's climate science report. All of these are expected to occur by 2100.
The researchers described such a scenario as "catastrophic" for the planet.
"It really is pretty grim," Bamber said. "Two meters is not a good scenario."
Melting Of Ice Sheets
In the UN's 2013 report, the climate panel predicted that global sea levels would increase by about 52 cm. to 98 cm. (20.4 inches to 38.5 inches) by the end of the century following the current trajectory.
However, scientists argue that these estimations are still quite conservative. Some believe that the current models used to determine the melting of the ice sheets were flawed, and that they were not able to factor in all of the uncertainties.
They made use of newly developed process-based models capable of predicting scenarios on a regional and continental scale.
The researchers also looked at the potential impact such an increase in seal levels would have on human populations.
Bamber said people living in low-lying coastal areas would be the ones affected the most, with mass displacements likely to occur as a result of higher water levels. Those living in small island countries in the Pacific Ocean also face an "existential threat" since their lands would become largely uninhabitable.
The study identified an extreme-case scenario where as much as 1.79 million square kilometers (691,120 sq miles) of land would be swamped by the sea. Such an increase in the world's sea levels threatens the lives of about 187 million people, or at least 2.5 percent of global populations.
The chances of this worst-case scenario happening is about 5 percent, according to the researchers. However, it should still be taken seriously.
Their findings point to a plausible threat that global sea levels could rise substantially as a result of both Antarctic and Greenland ice sheets melting.
Bamber said mankind only has a narrow window of opportunity to prevent some of the worst consequences, including a significant increase in sea levels.
"What we decide to do collectively as a species politically, globally, over the next decade is going to determine the future of the next generations in terms of the habitability of the planet and what sort of environment they live in," Bamber noted.