A recently released study indicates that a climate catastrophe may be just over the horizon, with rapidly melting ice caps set to put major metropolises like Shanghai and New York City at risk of becoming uninhabitable.

Other coastal settlements in China, from the southern province of Hainan to North China’s Liaoning, would also be in danger, including the southern metropolis of Shenzhen – which is home to over 12 million people.

The new report, which was published on May 20 by the journal Proceedings of the National Academy of Science of the United States of America, has received extensive media coverage this week and claims that sea levels could rise by more than 2 meters by the end of this century in a worst-case scenario. This number is more than double the estimated 1-meter rise in ocean levels put forth by the United Nations’ Intergovernmental Panel on Climate Change(IPCC) in a report released in 2014.

A computer-simulated rendering of what Shanghai will look like if the planet heats up by 4 degrees Celsius. Image via Climate Central

The worst-case scenario poised by scientists is a situation in which Earth heats up by 5 degrees Celsius, according to Business Insider. And while the chances of this nightmarish scenario coming to pass are estimated at around only 5%, the researchers behind the study note that it is still “plausible” that sea levels could rise by 2 – or more – meters.

CBC reports that the Fifth Assessment Report released by the IPCC in 2014 only looked at likely scenarios, that is: climate change outcomes within a 17% to 83% probability range. This newest report looks at a wider set of probabilities, ranging from 5% to 95%. The Canadian media company additionally notes that there is a 5% chance of sea levels rising by 7.5 meters by 2200. Yikes.

And while 5% may seem low, many experts are cautioning that preparation for a worst-case situation is important nonetheless. Associate Professor Paul Myers from the University of Alberta’s department of atmospheric sciences told CBC that the risk of a huge increase in sea level is comparable to a massive asteroid strike, stating: “[Astronomers] are talking about probabilities of well under 1% – 0.1% or less – and they’re still planning for it, because if it ever were to happen, it would be catastrophic. Here we’re talking about 5%.”

Myers was not a participant in the recently published study.

Antarctica lost an average of 252 billion tons of ice per year over the past decade. Image via Pixabay

If the worst possible outcome does come to pass, as many as 187 million people could be displaced by rising sea levels, and 1,789,992 square kilometers of land – an area larger than China’s Xinjiang Autonomous Region – will be lost under the waves.

The study’s findings also indicate that Greenland’s ice sheets are shedding an average of 286 billion tons of ice annually, with ice melting six times faster than just four decades ago, according to Business Insider. In the past decade, Antarctica lost an average of 252 billion tons of ice per year, considerably more than the 40 billion tons lost yearly during the 1980s.

[Cover image via Climate Central]

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