Greenland ice loss expected to raise global sea levels by nearly a foot, new research finds

The study, published Monday in the journal Nature Climate Change, found that the overall loss of ice from the Greenland Ice Sheet will trigger at least 10 inches of sea level rise, regardless of global warming scenarios. This is generally the same amount that the world’s seas have already risen in the last century from Greenland, Antarctica and thermal expansion (when ocean water expands as it warms up) combined.

Researchers from the Geological Survey of Denmark and Greenland observed changes in the volume of the ice sheet in and around Greenland and found that meltwater runoff was the main driver. Using a “well-established theory”, scientists were able to determine that around 3.3% of the Greenland ice sheet – the equivalent of 110 trillion tonnes of ice – will inevitably melt as the ice sheet reacts to the changes that have already happened.

Sea level rise from this melted ice will occur “regardless of any foreseeable future climate trajectory in this century”, according to lead author Jason Box, a scientist with the Geological Survey of Denmark and Greenland. “That water is technically already under the bridge.”

Although the authors did not specify a timeline, they predict that sea level change may occur by the end of the century.

The research was only intended to estimate a minimum, or “a very conservative lower bound”, of sea level rise from melting Greenland, “and in the virtually certain event that the climate continues to warm, l sea ​​level engagement is only increasing,” Box said. .

Massive ice caps can melt quickly when the air temperature is warm, but warmer ocean water also erodes the ice cap at the edges.

The findings follow a report on sea level rise in 2022 released earlier this year by the National Oceanic and Atmospheric Administration, which found that US coasts could expect sea level rise. 10 to 12 inches over the next 30 years. This will cause high tide flooding more than 10 times more frequent and allow storm surges to travel further inland, the report said.

Greenland contains enough ice that, if it all melted, it could raise sea levels around the world by about 25 feet. The researchers point out that a sea level rise of 20 feet does not mean it will rise evenly around the globe, leaving some places devastated while sea levels drop in others.

When places like Greenland lose ice, for example, they also lose the gravitational pull of ice on water, which means sea levels in Greenland drop as levels rise elsewhere, a said William Colgan, senior researcher at the Geological Survey of Denmark and Greenland. The pace of this change is the problem, Colgan told CNN’s Bill Weir during a research trip in the summer of 2021.

“It will be really difficult to adapt to such rapid changes,” said Colgan, standing at Greenland’s Jakobshavn glacier, where the fjord is full of ice that has broken off from the glacier.

Before human-caused climate change occurred, temperatures near 32 degrees Fahrenheit in Greenland were unheard of. But since the 1980s, the region has warmed at around 1.5 degrees per decade – four times faster than the global rate – making it all the more likely that temperatures will cross the melting threshold.

Several days of unusually warm weather in northern Greenland recently triggered a rapid melt, with temperatures around 60 degrees, 10 degrees warmer than normal for this time of year, scientists told CNN.

The amount of ice that melted in Greenland between July 15 and 17 alone – 6 billion tons of water per day – would be enough to fill 7.2 million Olympic swimming pools, according to data from the US National Snow and Ice Data. Center. .

Global scientists have said the accelerating trends in climate change are quite clear and unless emissions are reduced immediately, many more extreme melting events will continue to occur more intensely and more frequently.

CNN’s René Marsh and Angela Fritz contributed to this report.


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