September 26, 2023

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Antarctica in trouble

Antarctica in trouble

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picture: David Taylor/Science Photo Library (AP)

Antarctica is home 90% of the world’s fresh water, are trapped in the continent’s massive ice sheets – and much of that ice’s stability is at serious risk from global warming. Two studies published in the journal This week, Nature takes a look at how climate change is affecting conditions in Antarctica’s ice sheets, spelled From the bleak future of sea level rise.

the first study Seen at how two Antarctica Ice sheets are affected by what happens with ice shelvesAnd the that serve as a protective struts. ice shelves stretch out Oceanwhile leaves cover the ground.

“Ice shelves are huge, hundreds or even thousands of meters thick of ice, and some are as large as France,” said lead author Chad Green, a postdoctoral research fellow at NASA. Jet Propulsion Laboratory, via email. “Ice shelves float over the ocean in hydrostatic equilibrium, so when an iceberg breaks off the ice shelf, there is no direct effect on sea level. But when an ice shelf is accelerated, it gets a little smaller and weakens a little.”

Ice shelves usually contain healthy birth cycle They are able to replenish the ice they have lost. But climate change has helped speed up the calving process, weakening the ice shelves from below in heating water and making it harder for the shelves to regenerate. To understand what this might mean for sea-level rise, Green and his colleagues used satellite data to create a series of high-resolution maps of the Antarctic coast over the past 25 years.

“What we found is that the ice shelves in Antarctica were crumbling at the edges,” Green said. In general, they Identifies that Antarctica has lost more than 14,280 square miles (37,000 square kilometers) of ice shelf area since 1997 (“TA hat the size of Switzerland,” Green added). It means that the ice shelves on the continent have lost about 12 million metric tons in the past 25 years, About double the previous estimate of the loss. All this collapse could herald bad news for the long-term stability of the continent’s ice sheets.

“Over the past quarter century, shrinking and weakening ice shelves has allowed massive glaciers in Antarctica to accelerate and increase their contribution to sea level rise,” Green said. “The most important impacts were seen in Thwaites and the Pine Island glacier in West Antarctica, and there is no indication that either will slow down anytime soon.” (The Thwaites Glacier is commonly referred to as the “Resurrection Glacier,” and it exists very big problem.)

Even ice sheets that were previously thought to be stable They show signs of stress. second study out this week Considers the possible fate of a critical ice sheet – the East Antarctic Ice Sheet, the largest Antarctic ice sheet ice sheets and The largest fresh water tank on Earth. This ice sheet is traditionally considered more protective than the ice sheetEastern ice cover – which includes the Thwaites and Pine Island glaciers – due to less exposure to warming ocean waters. But if the East Antarctic ice sheet is threatened, it could potentially be catastrophic news for the planet: The ice sheet contains enough water to raise sea level by more than 170 feet (52 meters).

Chris Stokes, lead author of the study and professor of geography at Durham University: “We know that small mountain glaciers around the world are shrinking rapidly and contributing to sea level rise.said in E-mail. “We also know that the larger Greenland ice sheet is also losing mass and contributing to sea level rise, as is the western part of the Antarctic ice sheet. However, we don’t know much about what might happen to the East Antarctic ice sheets.”

To get a better idea of ​​what the future of the East Antarctic ice sheet might look like, Stokes and colleagues conducted a review of previous work on how the ice sheet responded to past warm periods and current levels of change, adding, “A little new crunching of numbers based on computer simulations,” he said. that predicts how this giant ice sheet will contribute to sea level rise in the future.”

There’s a bit of good news here: the authors say the ice sheet will likely remain flat in the short term, and keeping the temperature rise below 2°C by 2100 will keep the ice sheet from collapsing in the long term. But the study also suggests that the East Antarctic ice sheet is already showing signs of stress from climate change, and time to act is running out. The study found that letting the world warm outside the boundaries of the Paris Agreement could mean that the East Antarctic ice sheet could make sea levels rise by as much as 3 to 10 feet (1 to 2 meters) by the year 2300.

“The main conclusion from our work is that if we can meet the Paris climate agreement, we can almost certainly avoid a significant sea-level contribution from East Antarctica,” Stokes said. “And then, I think, of all the doomsday stories we hear about, our study offers at least some hope that we have a small chance over the next few decades to protect this ice sheet. As we conclude in the paper: The fate of the world’s largest ice sheet is in our hands. “.

While these two papers deal with different scenarios, the message is clear: Seriously curbing warming is critical to helping us keep everything above water.

“Antarctica is changing. Its ice sheets are falling apart, and sea levels are rising in response,” Green said. “But like Stokes et al. Put the paper well, there is still time to work.”

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