"Nonlinear Melting" - Greenland's Ice Loss Rate Half Again That Of Preindustrial Era, Accelerating
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Using a drill to extract core samples from the ice sheet itself, the research team was able to extend records for Greenland ice melt back to 1650. They found that melt and runoff from the ice sheet have recently accelerated beyond the range of past variability.
As Trusel explained, this means melting of the ice sheet has been relatively steady in the past, and has only rapidly increased over the past few decades. "It's now increased to levels we haven't seen before, at least in the last few centuries and probably not in the last 8,000 years," he said. "The changes we're seeing today are exceptional and unprecedented in a longer-term context."
Researchers have described this rise in melting as "nonlinear," because for every degree of global warming melting increases at a disproportional rate. Greenland ice sheet melt is now "outpacing" warming, Trusel said. For example: in the past, 1 degree Celsius (1.8 degrees Fahrenheit) of warming might have had little or no impact on the ice sheet, but today the same amount of warming produces twice as much melt, or more.
Alun Hubbard, a professor of glaciology at Aberystwyth University, said researching these trends over the long term is incredibly important to understanding global warming. It's also particularly valuable in combating climate change skepticism, he added. "It's really important to show that what's happened in the last couple of decades is something very different and very new," he said.
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https://www.dw.com/en/greenland-ice-sheet-melting-at-exceptional-rate/a-46586980