On thin ice: Melting of the doomsday glacier in Antarctica could raise sea levels by 65 centimetres

Modelling shows that the thawing of just one of Antarctica’s glaciers, the Thwaites Glacier in the West Antarctic Ice Sheet, could raise global sea levels by an average of more than half a metre.

As the global climate warms, ice in the polar regions melts, causing sea levels to rise and making the salty ocean waters fresher.

It’s not that complicated.

But scientists are still poring over data to try and underscore the urgency of the potentially catastrophic impact of human-induced climate change on the global ecosystem and on civilisation itself.

Researchers from the British Antarctic Survey revealed their findings on the vulnerability of the Thwaites Glacier to collapse in two papers published (here and here) in Nature. The results come from measurements taken by drilling through approximately 587 metres of ice and using semi-autonomous underwater vehicles to measure oceanic properties around the glacier.

Their projections show that complete collapse of the Thwaites Glacier could increase global sea levels by 65 cm over a century or so.. The glacier’s collapse could also destabilise neighbouring glaciers, leading to an additional three-metre rise.

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Read more: Cold comfort: How Antarctica represents two sides of climate change

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Senior scientist with the Australian Antarctic Division, Dr Ben Galton-Fenzi, is a glaciologist who spoke with Cosmos about the researchers’ findings.

Galton-Fenzi, who is not part of the team that published either Nature article, notes that the Thwaites Glacier has been dubbed the “Doomsday Glacier” and has been rapidly retreating for years.

“The biggest reason why folk think it started to retreat is really due to changes in the ocean,” Galton-Fenzi explains. “Due to climate change driving a shift in the winds in Antarctica, which turns more warm water onto the shelf, you get that relatively warmer water driving the increase in melting. Then you’re actually exposing more ice to the ocean, so it then melts more.”

The glaciologist notes that much of the modelling has a relatively high uncertainty because so much ice is below sea level, but recent technological developments like autonomous vehicles has increased scientists’ ability to see below the surface.

Galton-Fenzi says sea level rise is already happening.

“The bottom line for me is that it’s already changing. Sea levels are going to go up, and the oceans are going to get fresher. If the oceans get fresher, that’s going to change things like the global overturning circulation, the ocean conveyor belt. The question is: given the amount of warming is already in the atmosphere and in the oceans, how much sea level rise are we already committed to now?

“The biggest uncertainty in future sea level comes from Antarctica. It’s massive. The projections are several tens of centimetres by the end of the century, but it could be metres. A lot of that isn’t going to come from the West Antarctic Ice Sheet, it’s going to come out of the East Antarctic Ice Sheet in our backyard,” Galton-Fenzi adds.

The Nature papers come as other research published in Nature Communications notes that if global warming is not restricted to 1.8°C, then melting from the Antarctic and Greenland ice sheets alone will see sea levels rise around 1.4 metres.

Lead author Jun-Young Park tells Cosmos that “recent research says that 1m sea level rise in 2100 CE can threaten more than 400 million people.”

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“There are a lot of communities that live within what we call the low elevation coastal zone,” says University of New South Wales social sciences PhD candidate Anne Maree Kreller. “We’re talking about a meter – a lot of people live in just a meter above sea level. There are estimates that approximately 85% of the Australian population live on the coast.”

Kreller specialises in social movements and community-based decision-making.

“Start thinking about sea level rise, and you start thinking about the tides, storm surges, and you’ve got this accumulation of risks to human communities. Think about the global community, like Tuvalu and Bangladesh where people live in the Delta. What happens when you start to have storms and cyclones is really catastrophic. And the thing about sea level rise that makes it really difficult to connect to people’s daily life, is its slow moving.”

Kreller says there are two aspects to tackling sea level rises.

“One is mitigation, and stopping the use of fossil fuels and addressing this, and the other is the obviously the adaptation space and starting to ask some of those questions that are quite difficult,” Kreller explains.