(ORDO NEWS) — The Thwaites Glacier, roughly the size of Florida or the UK, accounts for more than half a meter of global sea level rise potential.
Its collapse would also destabilize the rest of the West Antarctic ice sheet, eventually leading to a three-meter rise in global sea levels.
All this would lead to a catastrophic scenario: many cities would become uninhabitable, and many agricultural lands would become unusable due to sea salt poisoning.
While studying part of the West Antarctic ice sheet, dubbed the Doomsday Glacier, scientists have found that warm water seeps into its weakest or most vulnerable spots, exacerbating the melting caused by rising temperatures.
Two new studies provide a clearer picture of the changes taking place under the huge glacier.
The authors of the study drilled holes nearly 600 meters deep in ice below the Thwaites Glacier ground line, where the glacier stops sinking directly on the bedrock and begins to float.
Thanks to this hole, scientists were able to measure ocean temperature, salinity, melting rate and the speed of the glacier.
Another group of researchers made observations using an underwater vehicle, which could also study the shape of the bottom of the ice.
They found that the water at the bottom was too warm for the Antarctic environment: 2.5 °C all year round.
Consequently, most of the study area is melting more slowly than expected, but there are important points that compensate for this.
“The rate of melt is much slower than we might think given how warm the ocean is,” says oceanographer Peter Davies of the British Antarctic Survey in Cambridge.
“The find may sound like good news, but it’s not.
Despite such low rates of melt, we are still seeing a rapid retreat” as the ice melts faster than it recovers.
Results worse than expected
When the researchers sent a remote-controlled vehicle down the well, they found that most of the melting occurs where the glacier is already under mechanical stress, inside massive cracks called basal fissures.
Melting is especially important in cracks, as water channels heat through them, and salt can be transferred to the ice, widening the cracks and breaking the ice.
Thus, while vertical melt along the base of the ice shelf was less than expected, melt along sloping ice in these cracks is much greater and may be an important factor.
“Our results came as a surprise, but the glacier is still in trouble.
If the ice shelf and the glacier are in equilibrium, the ice leaving the continent will match the amount of ice lost from the melting and calving of icebergs.
We have found that, despite a small amount of melt, the glacier is still rapidly retreating, so it does not seem to take much effort to bring the glacier out of balance,” concluded Peter Davies of the British Antarctic Survey.
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