HE ice from the poles melting much faster than previously thought until now. One of the consequences of this fact is that the extent of future sea level rise caused by climate change has been underestimated. It will increase by 200% more than what scientists have calculated, with consequent danger to coastal populations worldwide.
While conducting research on the Petermann Glacier in northwest Greenland, researchers from the University of California at Irvine (UCI) and NASA’s Jet Propulsion Laboratory (JPL) discovered an unknown way in which ice and ice interact in the ocean.
Glaciologists pointed out that their findings could mean: scientific community ‘grossly’ underestimates the magnitude of future sea level rise caused by the deterioration of polar ice.
This ice loss In Greenland, as in the Arctic and the rest of Antarctica, it has accelerated exponentially in recent years. And it did much more than the climate models scientists use show.
Using satellite radar data from three previous European missions, the UCI-NASA team discovered that the areas where the Petermann Glacier connects to the mainland – where ice begins to break off from the ground and float in the ocean – change significantly during tidal cycles. permissive warm seawater interacts with ice and melts it at an accelerated ratemuch higher than expected.
Very high melting rates
The results of the research published in the Proceedings of the National Academy of Sciences (PNAS) reveal that: Between 2016 and 2022, after Petermann retracted the landline by almost four kilometers, the hot water created a 200-metre-high hollow in the lower part of the glacier.remaining open through 2022.
” ice ocean interactions “It makes glaciers more susceptible to ocean warming,” said Eric Rignot, UCI Professor of Earth Systems Sciences and NASA JPL Researcher.
“These dynamics were not included in the models, and if we included them, they would increase their sea level rise estimates by up to 200% for all glaciers that connect to the ocean, not just Petermann. Greenlandand for everyone Antarctica‘, he warned.
“The Petermann scratch line moves between 2 and 6 kilometers as the tides go in and out,” said lead author Enrico Ciraci, UCI assistant scientist for Earth Systems Science and a NASA postdoctoral fellow. “This is an order of magnitude larger than expected,” he said.
Until now, it was believed that ground lines at the bottom of ocean-bound glaciers do not move during tidal cycles and do not experience ice melt.
But this new study forces us to change that thinking because warm ocean water seeps under the ice from pre-existing subglacial channels, causing higher melting rates in areas where glaciers meet the mainland.
irreversible loss of ice
The Greenland ice sheet has lost billions of tons of ice to the ocean in recent years.The report underlines, and most of the loss is due to the warming of groundwater in the ocean as a result of climate change to which the Earth has been subjected.
“Exposure to ocean water violently melts ice on the glacial front, eroding resistance to glacial movement above ground, ice slides faster towards the sea‘ stressed Rignot.
A similar process was recently confirmed by researchers from the British Antarctic Service at the Thwaites Glacier at the South Pole. “The rapid retreat of the Thwaites Glacier in West Antarctica appears to be driven by different processes beneath the floating ice shelf,” the scientists wrote. Said.
New observations in the region where the ice enters the ocean, published in the journal ‘Nature’, show that Melting in cracks and crevices is also much faster than expected. At Thwaites, a glacier the size of Great Britain. In his case, the point where the glacier meets the seafloor has retreated 14 kilometers since the late 1990s.
“Most of the ice sheet is below sea level and is vulnerable to rapid and irreversible loss that could raise global sea level by more than half a meter over the next few centuries.“Warn the researchers. Hot water enters through cracks, helping to erode the glacier at its weakest points,” they concluded.
Reference report (Petermann Glacier): https://www.pnas.org/doi/10.1073/pnas.2220924120
Reference report (Thwaites Glacier): https://www.nature.com/articles/s41586-022-05586-0
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