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The Pine Island glacier in the western part of the Antarctic ice sheet is responsible for more than a quarter of Antarctica’s contribution to global sea level rise over the past decades. Now, a new study shows that it is more susceptible to rapid melting than previously thought, as climate change weakens the natural braking system.
Why it matters: The future of a glacier with about 160 trillion tons of ice is at stake, which if everything in the ocean melted would cause sea levels to rise by about 1.6 feet.
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The study, published Friday in the journal Science Advances, uses satellite measurements and a computer model to find that there has been a more than 12% increase in the speed of this glacier’s flow into the sea from late 2017 to 2020, the period that saw the floating ice shelf dumped. The glacier has many large icebergs.
Threat Level: Intense scientific examination is focused on this glacier and the neighboring Thwaites Glacier, also called the “Doomsday Ice”, due to the possibility that it may already have crossed the tipping point into a runaway melt that is virtually unstoppable.
Photo: Ian Joughin et al. / Advanced Science
Details Scientists from the University of Washington and the British Antarctic Survey combined advanced satellite data with a computer model of ice movement to determine what’s driving the acceleration.
Until late 2017, the glacier was melting mainly due to the intrusion of relatively temperate ocean waters into the bottom layer of the floating ice shelf.
These shelves act like a door rail, preventing ice inside. However, it can be a glacier’s Achilles heel when it disintegrates or weakens, due to melting from above, below, or both.
From September 2017 to March 2020, the Pine Island Glacier ice shelf lost 20% of its area, reducing its ability to support inland ice.
In all, the cliff retreated inland by about 12.4 miles during this period, and the glacier sped up its flow into the sea as well.
What they found: Instead of melting from below, as it did during an earlier period of relatively rapid melt, scientists found that the ice shelf is retracting due to calving, or large icebergs breaking off at the edge of the shelf.
The story continues
This presents a greater level of risk that scientists have not considered before. What looked like ice-shelf loss in 100 years or more has now been pushed back into the next two decades, lead author Ian Joughin told Axios.
What they’re saying: The shelf appears to be a victim of the climate-change-related acceleration of the glacier movement from the 1990s to 2009.
“What our study shows is that the shelf [is] Maybe it’s detaching in response to acceleration caused by early melting, so we’ll probably have to worry about losing the shelf maybe sooner (maybe this decade) rather than later,” Goggin told Axios via email.
“It might be a long time for the shelf to collapse completely, but not that big [of] One.”
What’s next: Researchers are eagerly waiting to see what the glacier and its ice shelf will do next, which may help determine the future of some coastal communities around the world.
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