Greenland, home to Earth's second-largest ice cap, has lost ice over time in recent decades – an almost six-fold increase that could contribute to future sea-level rise, according to a new study based on almost one-half of the century.
The findings released Monday in the National Academy of Sciences estimate that between 1980 and 1990, the Greenland glaciers dumped just 51 billion tons of ice into the ocean and 286 Billions have lost tons between 2010 and 2018.
The result is that since 1972, sea level rise by almost 14 millimeters since 1972 has found half of it in just eight years.
And the losses are likely to worsen. The regions with the greatest potential ice loss ̵
Should they start to melt and chunks of it lose ice faster, then the total ice loss in Greenland – and its contribution to sea-level rise – could even increase.
Eric Rignot, a scientist of Earth Systems at the University of California at Irvine and NASA, one of the authors of the study, said in an email on Monday that the study highlights the recent mass losses in Greenland in a longer-term context provides.
"The 1980s were the transitional period when the Earth's climate migrated significantly away from its natural variability as a result of man-made greenhouse gas emissions," Rignot said.
He said that the shift was in part worrying about what it plans for the future, especially in connection with a potential loss of ice in the Antarctic.
"The whole periphery of Greenland is affected, and I am particularly concerned about the northern regions where the potential sea level rise is already strongest," said Rignot, who led a study last year It has been found that the Antarctic region loses six times as much ice as it did four decades ago – an unprecedented pace in the age of modern measurements.
"The Antarctic, some large sleeping giants in the eastern Antarctic, are waking up, and much of the West Antarctic is seriously affected, none of which is good news," Rignot added.
"We should prepare ourselves for what is coming, and take measures as soon as possible to avoid the most drastic scenarios."
Greenland is the largest island in the world. It is home to more than 200 large glaciers, many of which stretch all the way from the kilometer-thick central ice sheet to the deep waters of the ocean. They flock out into the fjords, narrow gorges partly under water.
At the edge of the glacier, large pieces of ice often break spectacularly and cause "ice-quake" events that can be discovered around the world.
Ice loss, however, is far less dramatic. It consists of a continuous melt that flows out into streams on the surface of the ice sheet, but also in the form of underwater currents. This can be partly due to the sudden disappearance of meltwater lakes on the surface of Greenland.
Researchers have known for some time that ice losses are worsening. Greenland is located in an Arctic zone warmed by more than 2 or even 4 degrees Celsius above pre-industrial levels.
This warming has led to dramatic changes, such as The huge Petermann Glacier lost several "ice islands" in 2010 and 2012, larger than Manhattan.
But just how much ice has Greenland lost? This question was difficult to answer. But it is very important, as each 360 billion tons corresponds to one millimeter of sea-level rise.
Record of satellites, gravity measurements and other tools, Rignot and his colleagues at the University of California, Irvine and NASA's Jet Propulsion Laboratory and his colleagues in France, Denmark and the Netherlands say they are answering this 46-year-old question can.
The researchers found that Greenland was more or less in the air from 1972 to 1990. She lost ground as glaciers flowed into the sea and broke off large icebergs, but she also recovered them when snow fell on the ice cover.
However, this has changed rapidly in the last 30 years. The ice losses in the 1990s amounted to about 41 billion tons per year, in the 2000s it was 187 billion tons – and in the 2010s 286 billion tons.
Based on the results of models that simulate the past climate of Greenland, "the stream says." Melting and draining has been unprecedented in the last 150 years, "said Marco Tedesco, a Greenlandic expert at the Lamont Doherty Earth Observatory at Columbia University. in an e-mail.
He said the newspaper "also highlights the importance of understanding and quantifying glaciers." Respond to warming and increased surface melting.
The melting in Greenland came from several places, with the famous Jakobshavn glacier losing 323 billion tons during that period, which caused the sea level to rise by almost a millimeter – the long but flat Humboldt glacier, the fifth largest loser an estimated 152 billion tons.
And there are glaciers that are not losing much yet are rapidly changing, including Petermann, Nioghalfjerfjorden and Zachariae Isstrøm, huge glaciers that have begun to change in the northeast and northwest of Greenland
If they continue to accelerate, the losses could be enormous: Nioghalfjerfjorden and Zachariae Isstrøm, for example, each contain more than half a meter (or over 1.6 feet) of potential sea level rise.
The causes of the current changes are According to Rignot many times, including warmer temperatures, the surface Grönl Ands more ice melt, but also warmer Atlantic waters that reach the glaciers.
"This is consistent with our understanding of the effects of climate change on ice, except that it happens earlier and faster than anticipated by models," Rignot said.
Rignot said that some ice loss – and a corresponding sea-level rise – are probably already inevitable, as carbon dioxide emissions remain in the atmosphere for decades. However, he said that what people will do in the future can certainly influence the nature of ice in Greenland and the Antarctic.
"If we do something now, it will take 30 years for the climate to take effect, and for decades to prevent the melting of glaciers. Probably half of that signal is already set in stone," he said.
"However, with every 10 [centimeters] of sea-level rise, the sea-level impact on humanity will increase sea levels by several meters in the coming century, unless we do something drastic."
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