The dismaying acceleration of ice sheet melting in both Greenland and Antarctica threatens to raise global sea levels by more than two meters (6.6 feet) by the end of this century, which is a much faster rate than predicted back in 2013.

A new scientific study released this week blamed the much faster ice melt on the continuing emissions of heat-trapping greenhouse gases (GhG) such as carbon dioxide and methane. The study noted that raising sea levels by two meters will submerge most coastal cities in Asia, as well as many major coastal cities such as New York, Los Angeles and Shanghai. Rampant sea level rise will displace up to 187 million people living at or near coastal areas, or 2.5 percent of the world's total population.

The study published in the journal Proceedings of the US National Academy of Sciences revealed that under the extreme-case scenario, about 1.79 million square kilometers (691,120 square miles) will be swallowed-up by rising seas. This lost land is equivalent to an area more than three times the size of California.

In the worst case scenario where global temperatures increase by 5 degrees Celsius (9 degrees Fahrenheit) by 2100, the two meter rise in sea level will be double the upper limit outlined by the UN climate science panel's last major report.

This report in 2013 predicted sea levels will rise between 52 cm and 98 cm (20.4 inches and 38.5 inches) by 2100 at the current trajectory. Many experts, however, rejected these estimates as conservative.

The outcome of the two meter rise in sea levels will be "catastrophic," said the study.

"It really is pretty grim," said study lead author Jonathan Bamber, a Professor of Physical Geography at the University of Bristol. "Two meters is not a good scenario."

Bamber said the mass displacement of people in low-lying coastal areas will likely trigger serious social upheavals worldwide. It’s also an "existential threat" to small island nations in the Pacific, which either be submerged or left uninhabitable.

The study, however, acknowledges only a 5 percent chance of the worst-case scenario occurring, but it says this shouldn’t be dismissed.

"Our study suggests that there is a real risk, a plausible risk of very substantial sea level rise coming from both ice sheets," said Bamber.

This disaster can still be avoided but only by a very narrow margin. Bamber said that what countries need 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.

The two meter rise predicted might also be conservative since scientists say the current models used to predict the influence of massive melting ice sheets are flawed and don’t capture all of the associated uncertainties.

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