As climate change warms the planet, glaciers are melting faster. Many will collapse by the end of the century, dramatically raising sea levels and flooding coastal cities and island nations.
A University of California, Berkeley scientist has now created an improved model of glacier movement that could help determine which Arctic and Antarctic glaciers are most likely to rapidly slide downwards and fall into the ice. ‘ocean.
The new model, published in the journal The Cryosphere, incorporates the effects of meltwater that infiltrates the base of a glacier and lubricates its downward flow. The model predicts that the most vulnerable glaciers are the thickest with a faster flow history. The research is supported by the US National Science Foundation.
“The model suggests that thick, fast-flowing glaciers are more sensitive to lubrication than thin, slow-moving glaciers,” Whyjay Zheng said. “Data from Greenland’s glaciers support this new finding, indicating that these fast, thick glacial beasts may be more unstable than we thought under global warming.”
Zheng built the new model to incorporate a mechanism that has become more prominent with global warming: meltwater penetrating to the bottom of glaciers and lubricating their downward motion across bedrock.
The Arctic and Antarctica have warmed more than the rest of the world – in March, Antarctica recorded record temperatures of 70 F above normal, while parts of the Arctic were warmer by more than 60 F than the average. Warmer weather is causing meltwater lakes to form on many glaciers. Lakes can break through the bottom of glaciers by a process called hydrofracture, flowing to the bottom of glaciers through crevices.
Glaciologists have already seen that the speeding up and slowing down of glaciers is linked to what happens at the front of the glaciers, where the ice melts into the ocean and meets warmer waters. When the front melts, or collapses, into the ocean, the remaining parts tend to accelerate.
Basal lubrication by meltwater appears to create a feedback loop that accelerates glaciers that have already accelerated for other reasons, such as terminal changes. “This is because thicker glaciers are more slippery, leading to more melting, then more slip, and so on,” said Maria Womack, program director in NSF’s Division of Atmospheric and Geospatial Sciences. .
Zheng added that “in Greenland, the speed of a glacier seems to be mainly controlled by the position of the terminus. If the terminus recedes, the glacier will accelerate; if the terminus advances, the glacier will slow down.
“People think that’s probably the main reason why glaciers in Greenland can speed up or slow down. But now we’re starting to think there’s another, maybe faster way to slow down or speed up. glaciers: basal lubrication”.
Zheng wrote and ran his model using Jupyter Notebook, a publicly available online interactive computing platform.
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