A glimpse of what New York City would look like in the worst scenario of sea level rise. (Photo: Climate Central)

Miami? Submarine. Norfolk? Submerged. New York City? Fuggedaboutit.

According to leading experts, in the worst-case scenario, parts of these cities and other US coastal cities could disappear from the sea by the end of the century, as the sea level rises due to global warming. planet. a study released Monday said. In fact, on average, the seas of the world could be higher by the end of the century if climate change continues.

This is an estimate that a group of 22 high-level scientists have developed using new techniques to measure melting ice in the polar regions of the world. The main cause of the rise of the seas will be the continuous melting of the gigantic ice sheets on Greenland and Antarctica.

While this is a high-end estimate, "we should not rule out a sea level rise of more than two meters (6.5 feet) if we continue on the same emission path" said Jonathan Bamber of the university, lead author of the study. from Bristol in the United Kingdom.

This is potentially double the upper limit suggested by the latest major report of the UN climate panel, according to New Scientist.

Human-caused climate change, or global warming, is caused by the burning of fossil fuels such as gas, coal and oil, which release greenhouse gases such as carbon dioxide ( CO2) and methane in the atmosphere. This additional CO2 causes a rise in the temperatures of the atmosphere and oceans to levels that can not be explained by natural causes.

A small boat in the Illulissat Icefjord, in the west of Greenland, overhung by icebergs that calved from the largest Greenland glacier, Jacobshavn Isbrae. (Photo: Jonathan L. Bamber)

Low coastal cities are the most vulnerable to rising seas, Bamber said. This includes cities in Florida and Louisiana, as well as California cities such as Los Angeles and the San Francisco Bay Area.

Worldwide, "such a global rise in sea level could result in land loss of almost 700,000 square miles," he said. This equates to an area three times larger than that of the State of California.

Other major global cities partially lost in the sea include London and Rio de Janeiro.

Such a rise in water levels would also engulf "critical areas of food production and a potential displacement of about 187 million people", which represents about 2.5% of the world's population.

"A sea level rise of this magnitude would clearly have profound consequences for humankind," said Bamber.

More: "Extraordinary": Nearly a quarter of the ice in West Antarctica is now "unstable"

More: Carbon dioxide levels reached the benchmark at 415 ppm, the highest level of history

And yes, the seas have gone up and down many times before. The novelty is the enormity of coastal development that will have to be protected, moved or abandoned.

Sea level has risen nearly 20 cm in the world since 1880 but, unlike water in a bathtub, it does not increase evenly.

Over the past 100 years, it has climbed about a foot or more in some US cities because of ocean currents and soil subsidence: 11 inches in New York and Boston, 12 in Charleston, 16 in Atlantic City, 18 in Norfolk and 25 in Galveston. , Texas, according to a recent analysis by the United States of today on tide gauge data collected by the National Oceanic and Atmospheric Administration.

Here's why: As the Earth's temperature heats up, the seas are also warming up. Greenhouse gases that retain heat result in the melting of more terrestrial ice (glaciers and ice sheets) and the dilation of water. The warmer water simply occupies more space than the colder water.

Scientists say that global warming will be the main cause of future sea level rise. Their biggest uncertainty is how quickly the huge ice cover of West Antarctic melts.

Referring to the new study, Bamber said it was "important to take into account the relatively low probability – but the high-impact consequences – of melting ice sheets in the future".

The study was published Monday in the journal Proceedings of the National Academy of Sciences.

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