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Fact: Earth's colossal ice sheets are melting:

Pay attention to Greenland.

The land's colossal ice sheet — around three times the size of Texas — is melting some 270 billion tons(opens in a new tab) of ice into the sea each year as Earth warms. And the inevitable sea level rise could be worse than scientists calculated: Researchers at NASA and the University of California, Irvine (UCI) found that warmer ocean water is seeping underneath and amplifying melting of Greenland's mighty Petermann Glacier, which ends in a great ice tongue floating over the sea. The scientists recently published their research in the journal Proceedings of the National Academy of Sciences.

The glacier lies in northern Greenland, a realm of the high Arctic. But that frigid location can no longer protect it. Scientists found the glacier is vulnerable to the incessantly warming seas. It's another whammy for melting Greenland, which is melting from above (warmer air) and below (warmer water).

Until 2015, satellite observations showed Petermann, a major ice outflow on Greenland, was in solid shape. Not anymore.

"Something changed during the last decade. Petermann was supposed to be a place where the ice was still stable," Enrico Ciraci, a NASA postdoctoral fellow and an Earth system scientist at UCI, told Mashable.

Ice loss is now ramping up.

"Warming oceans are accelerating the mass loss of this glacier," Ciraci, who led the research, said.

Not even the coldest glaciers are immune.

"It's surprising even Petermann isn't escaping the impacts of global warming," Josh Willis, a NASA oceanographer who researches melting in Greenland and had no involvement with the new research, told Mashable.

[...] For some of us, sea level rise might not be nearly as apparent or poignant as the increase in inferno-like Western wildfires, record-breaking heat waves, vanishing Arctic ice, and historic deluges. But it's happening, and it's speeding up.

Since the late 19th century, global sea levels have already risen by some eight to nine inches. Sea level rise each year more than doubled from 1.4 millimeters over most of the 20th century, to 3.6 millimeters by the early 21st century. From just the years 2013 to 2018, that number accelerated to 4.8 millimeters per year.

Yet, crucially, most sea level rise simulations and predictions don't take into account what's happening under Petermann and the many glaciers like it. This means we might be underestimating sea level rise over the coming decades and beyond. In the study, the researchers noted that such ocean melting "will make projections of sea level rise from glaciers potentially double."

"This process is not accounted for in many models today for sea level rise," Ciraci explained. "The potential contribution is significant."

Journal Reference:
Enrico Ciracì, Eric Rignot, Bernd Scheuchl, et al., Melt rates in the kilometer-size grounding zone of Petermann Glacier, Greenland, before and during a retreat [open], PNAS, 2023 120 (20) e2220924120. DOI: https://doi.org/10.1073/pnas.2220924120

Original Submission