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By Denise Chow
The largest ice shelf in the Antarctic may be more vulnerable to climate change than previously thought. A new study of lukewarm seawater seeping into a cavity beneath Ross ice floes shows that an essential part of the ice-chunk of the size of France is melting much faster than the others.
"We have identified a particularly vulnerable section where the melting rate is 10 times that of the rest of the pack ice," said Poul Christoffersen, co-author of the study, a specialist in glaciology at the Scott Polar Research Institute. Cambridge University. Ross's ice shelf is considered relatively stable, but Mr. Christoffersen stated that the location of the rapid melting coincided with an "anchor point", essentially a buttress that prevents the ice from s' flow and gives stability to the entire platform.
Ice shelves are thick, floating masses of Antarctic ice that form as neighboring glaciers head toward the sea. Previous research has shown that warm water from the deep ocean causes melting and the disintegration of some pack ice. As this happens, the flow of glaciers into the ocean accelerates, contributing to a gradual rise in sea levels around the world.
A study conducted in 2017 by researchers from Cornell University estimated that by 2100, 2 billion people around the world could be displaced by the rising seas, which would threaten to inundate the coastal communities and other low areas. Scientists estimate that the seas are currently growing at a speed of about 3 millimeters a year, more than a tenth of an inch.
The new research, published online April 29 in the journal Nature Geoscience, shows that another type of melting – on the surface of the water rather than at the bottom of the ocean – can also affect the stability of ice cream.
"This is a new source of extra heat that we consider important, especially for the Ross ice floe, which, because of its large size, is of particular concern," said Christoffersen.
Christoffersen and his colleagues spent four years studying the Ross ice floe and the seawater below. Scientists drilled an 850 meter deep hole in the shelf and dropped instruments inside to measure temperature, melting velocities, and ocean currents in the cavity.
The researchers found that strong offshore winds blow sea ice away from the front edge of the pack ice, exposing some areas of the ocean to the heat of the sun that was previously covered with ice. The heat of the water accelerates the melting of the ice.
Laurie Padman, senior scientist at the Seattle-based Earth & Space Research Institute, said the new study provided accurate measurements for a phenomenon observed on other iceplaces but poorly understood. "For the Ross ice floe, it's important because this melting takes place in a place where it could change the ability of the pack ice to strengthen the surrounding ice," he said.
The study does not directly link the observed meltdown to climate change, but Christoffersen said climate change probably plays a role. For example, warming temperatures could cause sea ice around ice trays to expand, allowing the wind to blow more easily and exposing seawater to the sun. "We think that melting could increase because of climate change," he said.
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