Human-driven climate change has set in motion massive ice losses in Greenland that couldn’t be halted even if the world stopped emitting greenhouse gases today, according to a new study published Monday.
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The findings in Nature Climate Change project that it is now inevitable that 3.3 percent of the Greenland ice sheet will melt — equal to 110 trillion tons of ice, the researchers said. That will trigger nearly a foot of global sea-level rise.
The predictions are more dire than other forecasts, though they use different assumptions. While the study did not specify a time frame for the melting and sea-level rise, the authors suggested much of it can play out between now and the year 2100.
“The point is, we need to plan for that ice as if it weren’t on the ice sheet in the near future, within a century or so,” said William Colgan, a study co-author who studies the ice sheet from its surface with his colleagues at the Geological Survey of Denmark and Greenland, in a video interview.
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“Every study has bigger numbers than the last. It’s always faster than forecast,” Colgan said.
One reason that new research appears worse than other findings may just be that it is simpler. It tries to calculate how much ice Greenland must lose as it recalibrates to a warmer climate. In contrast, sophisticated computers simulations of how the ice sheet will behave under future scenarios for global emissions have produced less alarming predictions.
A one-foot rise in global sea levels would have severe consequences. If the sea level along the U.S. coasts rose by an average of 10 to 12 inches by 2050, a recent report from the National Oceanic and Atmospheric Administration found, the most destructive floods would take place five times as often, and moderate floods would become 10 times as frequent.
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Other countries — low-lying island nations and developing ones, like Bangladesh — are even more vulnerable. These nations, which have done little to fuel the higher temperatures that are now thawing the Greenland ice sheet, lack the billions of dollars it will take to adapt to rising seas.
The paper’s lead author, Geological Survey of Denmark and Greenland scientist Jason Box, collaborated with scientists based at institutions in Belgium, Denmark, Finland, Norway, the Netherlands, Switzerland and the United States to assess the extent of ice loss already locked in by human activity.
Just last year, the U.N. Intergovernmental Panel on Climate Change — which generally forecasts lower figures for total ice loss from Greenland by the end of the century — projected around half a foot of sea-level rise from Greenland by the year 2100 at the high end. That scenario assumed humans would emit a large amount of greenhouse gases for another 80 years.
The current study, in contrast, does not factor in any additional greenhouse gas emissions or specify when the melting would take place, making the comparison with the U.N. report imperfect.
The finding that 3.3 percent of Greenland is, in effect, already lost represents “a minimum, a lower bound,” Box said. It could be much worse than that, the study suggests, especially if the world continues to burn fossil fuels and if 2012, which set a record for Greenland ice loss, becomes more like the norm.
But that aspect of the study offers hope: even if more sea-level rise is locked in than previously believed, cutting emissions fast to limit warming close to 1.5 degrees Celsius (2.7 degrees Fahrenheit) would prevent things from getting much worse.
Greenland is the world’s largest island and is covered with a sheet of ice that, if it melted entirely, could raise sea levels by more than 20 feet. That is not in doubt — nor is the fact that in past warm periods in Earth’s history, the ice sheet has been much smaller than it is today. The question has always been how much ice will thaw as temperatures rise — and how fast.
Melt rates have been increasing in the past two decades, and Greenland is the largest single ice-based contributor to the rate of global sea-level rise, surpassing contributions from both the larger Antarctic ice sheet and from mountain glaciers around the world. Greenland lies in the Arctic, which is warming much faster than the rest of the world.
Higher Arctic temperatures cause large amounts of ice on Greenland’s surface to thaw. While the island’s oceanfront glaciers are also shedding enormous icebergs at an accelerating pace, it is this surface melt — which translates into gushing ice rivers, disappearing lakes and giant waterfalls vanishing into crevasses — that causes the biggest ice losses.
10 steps you can take to lower your carbon footprint
The findings in Nature Climate Change project that it is now inevitable that 3.3 percent of the Greenland ice sheet will melt — equal to 110 trillion tons of ice, the researchers said. That will trigger nearly a foot of global sea-level rise.
The predictions are more dire than other forecasts, though they use different assumptions. While the study did not specify a time frame for the melting and sea-level rise, the authors suggested much of it can play out between now and the year 2100.
“The point is, we need to plan for that ice as if it weren’t on the ice sheet in the near future, within a century or so,” said William Colgan, a study co-author who studies the ice sheet from its surface with his colleagues at the Geological Survey of Denmark and Greenland, in a video interview.
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“Every study has bigger numbers than the last. It’s always faster than forecast,” Colgan said.
One reason that new research appears worse than other findings may just be that it is simpler. It tries to calculate how much ice Greenland must lose as it recalibrates to a warmer climate. In contrast, sophisticated computers simulations of how the ice sheet will behave under future scenarios for global emissions have produced less alarming predictions.
A one-foot rise in global sea levels would have severe consequences. If the sea level along the U.S. coasts rose by an average of 10 to 12 inches by 2050, a recent report from the National Oceanic and Atmospheric Administration found, the most destructive floods would take place five times as often, and moderate floods would become 10 times as frequent.
‘They are not slowing down’: The rise of billion-dollar disasters
Other countries — low-lying island nations and developing ones, like Bangladesh — are even more vulnerable. These nations, which have done little to fuel the higher temperatures that are now thawing the Greenland ice sheet, lack the billions of dollars it will take to adapt to rising seas.
The paper’s lead author, Geological Survey of Denmark and Greenland scientist Jason Box, collaborated with scientists based at institutions in Belgium, Denmark, Finland, Norway, the Netherlands, Switzerland and the United States to assess the extent of ice loss already locked in by human activity.
Just last year, the U.N. Intergovernmental Panel on Climate Change — which generally forecasts lower figures for total ice loss from Greenland by the end of the century — projected around half a foot of sea-level rise from Greenland by the year 2100 at the high end. That scenario assumed humans would emit a large amount of greenhouse gases for another 80 years.
The current study, in contrast, does not factor in any additional greenhouse gas emissions or specify when the melting would take place, making the comparison with the U.N. report imperfect.
The finding that 3.3 percent of Greenland is, in effect, already lost represents “a minimum, a lower bound,” Box said. It could be much worse than that, the study suggests, especially if the world continues to burn fossil fuels and if 2012, which set a record for Greenland ice loss, becomes more like the norm.
But that aspect of the study offers hope: even if more sea-level rise is locked in than previously believed, cutting emissions fast to limit warming close to 1.5 degrees Celsius (2.7 degrees Fahrenheit) would prevent things from getting much worse.
Greenland is the world’s largest island and is covered with a sheet of ice that, if it melted entirely, could raise sea levels by more than 20 feet. That is not in doubt — nor is the fact that in past warm periods in Earth’s history, the ice sheet has been much smaller than it is today. The question has always been how much ice will thaw as temperatures rise — and how fast.
Melt rates have been increasing in the past two decades, and Greenland is the largest single ice-based contributor to the rate of global sea-level rise, surpassing contributions from both the larger Antarctic ice sheet and from mountain glaciers around the world. Greenland lies in the Arctic, which is warming much faster than the rest of the world.
Higher Arctic temperatures cause large amounts of ice on Greenland’s surface to thaw. While the island’s oceanfront glaciers are also shedding enormous icebergs at an accelerating pace, it is this surface melt — which translates into gushing ice rivers, disappearing lakes and giant waterfalls vanishing into crevasses — that causes the biggest ice losses.