Greenland melts faster than previously thought – and will probably lead to a faster rise in sea level – thanks to the ongoing, accelerating warming of the Earth's atmosphere, a new study has revealed.
Scientists concerned about sea level The rise has long focused on Greenland's southeast and northwest, where large glaciers are pouring iceberg sized ice chunks into the Atlantic Ocean. These chunks float away and finally melt. However, a new study published on 21 January in the National Academy of Sciences revealed that the largest sustained ice loss from early 2003 to mid-2013 came from Greenland's southwest, where most of them did not "Whatever that was, it could not be explained by glaciers because there are not many," said Michael Bevis, lead author of the newspaper, Ohio Eminent Scholar and a professor of geodynamics at Ohio State University. "It had to be the surface mass ̵
This merger, by which Bevis and his co-authors believe that it is mainly caused by global warming, means that in the southwestern part of Greenland, growing rivers are pouring into the ocean during the summer. The main finding of their study: South West Greenland, which was not previously considered a serious threat, is likely to make a major contribution to sea-level rise.
"We knew that with the increasing extraction of iron we had a big problem with some large outlet glaciers," he said. "But now we recognize a second serious problem: Increasingly, large amounts of ice mass will leak out as meltwater, like rivers flowing into the sea."
The findings could have serious implications for US coastal cities, including New York, and Miami, as well as island states that are particularly prone to sea-level rise.
And there is no turning back, Bevis said.
"The only thing we can do is adjust and mitigate further global warming – it's too late to have any effect," he said. "This will lead to a further rise in sea level and we are seeing the ice cap reaching a watershed."
Climatologists and glaciologists monitor Greenland ice sheet since 2002, when NASA and Germany have joined forces to launch GRACE. GRACE stands for "Gravity Recovery and Climate Experiment" and includes two satellites that measure ice loss in Greenland. Data from these satellites showed that Greenland lost approximately 280 gigatons of ice per year between 2002 and 2016, which equates to a sea level rise of 0.03 inches per year. The ice loss rate across the island, however, was anything but stable.
Bevis' team used data from GRACE and GPS stations scattered along the Greenland coast to identify changes in the ice mass. The patterns they found show an alarming trend – until 2012, the ice was lost almost four times as fast as in 2003. The biggest surprise: This acceleration focused on Southwest Greenland, a part of the island that had not been before It was known that he lost ice so fast.
Bevis said a natural weather phenomenon – the North Atlantic Oscillation, which brings warmer air to West Greenland, as well as clearer skies and more solar radiation – relies on man-made climate change to lead to unprecedented levels of melting and runoff. The global warming of the atmosphere increases the summer time, especially in the southwest. The North Atlantic Oscillation is a natural – albeit unpredictable – cycle in which ice melts under normal circumstances. However, when combined with man-made global warming, the effects are recharged.
"These oscillations have happened forever," said Bevis. That's because the atmosphere at the base is warmer, and the temporary warming that has been driven by the North Atlantic Oscillation has been driven by more sustainable global warming. "
Bevis compared the melting of Greenland ice to coral bleaching: As soon as the ocean waters reach a certain temperature, the corals in this region begin to bleach. There were three global coral bleaching events. The first was caused by the El Niño 1997-98 and the other two events by the two subsequent El Niños. However, El Niño cycles have been going on for thousands of years – so why did they only create global coral bleaching since 1997?
"What happens is the surface temperature of the tropics in the tropics, it gets warmer and the air gets warmer," Bevis said. "The water temperature swings that come from an El Niño account for this global warming of the ocean, because of climate change, the base temperature is already close to the critical temperature at which coral bleaching occurs, so an El Niño pushes the temperature above the critical threshold In the case of Greenland, global warming has brought summer temperatures in a significant part of Greenland near the melting point, and the North Atlantic Oscillation has given the extra boost that melted large ice sheets. "
Before That In this study, scientists have understood that Greenland is one of the main factors for sea level rise – mainly due to its glaciers. However, Bevis said that these new findings show that scientists need to keep a close eye on the island's snowpack and ice fields, especially in and in southwestern Greenland.
GPS systems now monitor the Greenland ice rim area by most of its size. But the network is very sparse in the southwest, so it is necessary to condense the network in the light of these new insights.
"We will see a faster and faster sea-level rise for the foreseeable future," Bevis said. "When you reach this turning point, the only question is, how hard will it be?"