The retreat of the Thwaites Glacier is taking place in a different, more complex way than previously understood. Two studies published on 15 February 2023 in the journal Nature revealed new insight into the melting affecting the Thwaites glacier, which gives us a better picture of how this enormous glacier has responded to a warming climate and ocean.
“Despite small amounts of melting there is still rapid glacier retreat – so it seems it doesn’t take a lot to push the glacier out of balance.”
Dr Peter Davis gives a rapid rundown of what the new #ThwaitesGlacier science means.
The Thwaites Glacier is a broad glacier the size of the island of Britain or the US state of Florida, located in the Amundsen sea in western Antarctica. Since the late 1990s, the glacier has retreated 14 kilometres inland. This glacier’s nickname is “doomsday glacier,” because if it were to collapse completely this would lead to an increase in global sea levels amounting to 65 centimetres. The Thwaites Glacier is already contributing to around 4 per cent of global sea-level rise. The warming of the ocean and the atmosphere has had a considerable impact on this glacier, causing the changes we have been witnessing.
“These new ways of observing the glacier allow us to understand that it’s not just how much melting is happening, but how and where it is happening that matters in these very warm parts of Antarctica,” said Dr Britney Schmidt, associate professor at Cornell University and lead author of the second study. “We see crevasses, and probably terraces, across warming glaciers like Thwaites. Warm water is getting into the cracks, helping wear down the glacier at its weakest points.”
For these studies, the researchers used observations from a new underwater vehicle called “Icefin” and a hot-water-drilled access hole. The collected data shed light on the changes happening under the Thwaites glacier. The melting rate beneath much of the ice shelf, a mass of ice floating in the ocean, was lower than expected, with basal melt rates averaging no more than 2.0 to 5.4 meters per year.
Despite observations from a drilled access hole showing warm ocean waters beneath the Thwaites Glacier Eastern Ice Shelf, the basal melt rate is strongly suppressed due to the low current speeds and strong density stratification, reports a @Nature paper. https://t.co/xLbUgPG2llpic.twitter.com/E6yjFdEsb6
According to this new data, the melting of flat parts of the ice shelf is being suppressed by a layer of colder, fresher water between the ice shelf and the ocean. However, the melting in the Thwaites glacier’s ice shelf cracks and crevasses is happening much faster than previously thought. These cracks and crevasses in the ice base are particularly troubling as the warmer saltwater could widen these cracks.
“Our results are a surprise but the glacier is still in trouble. If an ice shelf and a glacier are in balance, the ice coming off the continent will match the amount of ice being lost through melting and iceberg calving,” explained Dr Peter Davis, an oceanographer at BAS and lead author on one of the studies. “What we have found is that despite small amounts of melting there is still rapid glacier retreat, so it seems that it doesn’t take a lot to push the glacier out of balance.”
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