Calving ice near Paradise Harbor in Antarctica in Jan. 2015. The continent’s ice sheet and the rest of the world’s land ice would melt if all the world’s fossil fuels were burned, a new climate study found. Credit Ralph Lee Hopkins/National Geographic Creative
Burning all the world’s deposits of coal, oil and natural gas would raise the temperature enough to melt the entire ice sheet covering Antarctica, driving the level of the sea up by more than 160 feet, scientists reported Friday.
In a major surprise to the scientists, they found that half the melting could occur in as little as a thousand years, causing the ocean to rise by something on the order of a foot per decade, roughly 10 times the rate at which it is rising now. Such a pace would almost certainly throw human society into chaos, forcing a rapid retreat from the world’s coastal cities.
The rest of the earth’s land ice would melt along with Antarctica, and warming ocean waters would expand, so that the total rise of the sea would likely exceed 200 feet, the scientists said.
Various measurements have captured the West Antarctic ice sheet changing very rapidly in the region where it flows into the Amundsen Sea.Scientists Warn of Rising Oceans From Polar MeltMAY 12, 2014
Researchers in Antarctica have been keeping track of temperature and other weather variables there since the late 1950s.West Antarctic Warming Faster Than Thought, Study FindsDEC. 23, 2012
Researchers sunk a mooring in Sermilik Fjord, where the glacier terminates, to measure water temperature, currents and other factors.Temperature Rising: As Glaciers Melt, Science Seeks Data on Rising SeasNOV. 13, 2010
LONG HAUL The Wissard team traveled 500 miles from McMurdo Station to the drill site at subglacial Lake Whillans.Wissard Project Seeks Signs of Life Under AntarcticaJAN. 14, 2013
To be blunt: If we burn it all, we melt it all,” said Ricarda Winkelmann, a researcher at the Potsdam Institute for Climate Impact Research in Germany and the lead author of a paper published Friday in the journal Science Advances.
A sea level rise of 200 feet would put almost all of Florida, much of Louisiana and Texas, the entire East Coast of the United States, large parts of Britain, much of the European Plain, and huge parts of coastal Asia under water. The cities lost would include Miami, New Orleans, Houston, Washington, New York, Amsterdam, Stockholm, London, Paris, Berlin, Venice, Buenos Aires, Beijing, Shanghai, Sydney, Rome and Tokyo.
Nobody alive today, nor even their grandchildren, would live to see such a calamity unfold, given the time the melting would take. Yet the new study gives a sense of the risks that future generations face if emissions of greenhouse gases are not brought under control.
“This is humanity as a geologic force,” said Ken Caldeira, a researcher at the Carnegie Institution for Science in Stanford, Calif., and another author of the paper. “We’re not a subtle influence on the climate system – we are really hitting it with a hammer.”
Climate scientists have long assumed that countries would recognize the dangers of continuing to dig up and burn the world’s fossil fuels. Yet they have been saying that for 30 years, and political efforts in that time to limit the burning have been ineffectual.
With a major push from President Obama, the nations of the world will convene in Paris in December in another attempt to reach an ambitious deal for reducing emissions. Yet Mr. Obama faces fierce opposition from the Republican Party in putting limits into effect in the United States, which uses more fossil fuels per person than any other large country.
The long-running political gridlock has prompted scientists to start thinking about worst-case scenarios. And recently, major advances have been made in the computerized analysis of the huge ice sheets covering Antarctica and Greenland.
The researchers involved in Friday’s paper decided to use one of these ice-sheet models to attempt the most detailed analysis yet of the potential consequences of burning all fossil fuels. As the first of its kind, the paper is likely to undergo intense scientific scrutiny.
In certain ways, the findings are reassuring. They offer no reason, for instance, to revise the sea-level forecast for the coming century.
A United Nations panel has said that the rise of the sea would not likely exceed three feet in that period, and would probably be less. While some island nations may be wiped out by a rise of that magnitude, experts believe most major cities could be protected from it, though at a likely cost in the trillions of dollars.
The ice sheets respond slowly enough to changes in the climate that it simply takes longer than a century for large-scale melting to begin. But from that point, the paper found, about half the Antarctic ice sheet would melt or fall into the sea in the first thousand years.
“I didn’t expect it would go so fast,” Dr. Caldeira said. “To melt all of Antarctica, I thought it would take something like 10,000 years.”
The more basic finding that the whole ice sheet could eventually melt is less surprising, at least to scientists who specialize in studying the history of the earth. “As a paleoclimate person, I don’t feel like this is necessarily a shock to me,” said Robert E. Kopp, a professor of earth system history at Rutgers University, who studies sea level but was not involved in the new research.
Paleoclimatologists have established that Antarctica was once a lush, green continent, icing over only in the past 35 million years, amid a general cooling of the world’s climate. Moreover, rates of sea level rise like those outlined in the paper have occurred in the past.
Human civilization is built on the premise that the level of the sea is stable, as indeed it has been for several thousand years. But the deeper history of the earth reveals enormous shifts, on the order of a hundred feet or more within a few thousand years.
Sea levels far higher than those of today have been documented at more than a thousand sites around the world. Along the East Coast, seashells from just 3 million years ago can be dug up by the shovel-full a hundred miles inland from the current shore.
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