Update on an Antarctic glacier

Hey, did you know that this blog is normally focused on climate change? Crazy, right? I’ve been caught up in current events, but I’m going to start doing more stuff about climate change and responding to it, along with other projects.

It’s been pointed out one or fifty times that the current COVID-19 crisis provides a nice demonstration of how the entire species can take dramatic action on an issue, provided those with power actually feel the need to do so. I think it also provides a useful parallel in that the warnings and calls for immediate action were downplayed and ignored for long enough that the problem grew out of control in many places. While the pandemic response has decreased air pollution and emissions quite a bit, that’s a small, temporary change, and the effects of over a century of accumulated CO2 continue on.

East Antarctica’s Denman Glacier has retreated 5 kilometers, nearly 3 miles, in the past 22 years, and researchers at the University of California, Irvine and NASA’s Jet Propulsion Laboratory are concerned that the shape of the ground surface beneath the ice sheet could make it even more susceptible to climate-driven collapse.

If fully thawed, the ice in Denman would cause sea levels worldwide to rise about 1.5 meters, almost 5 feet. With this sobering fact in mind, the UCI and NASA JPL scientists have completed the most thorough examination yet of the glacier and surrounding area, uncovering alarming clues about its condition under further global warming.

The team’s assessment is the subject of a paper published today in the American Geophysical Union journal Geophysical Research Letters.

“East Antarctica has long been thought to be less threatened, but as glaciers such as Denman have come under closer scrutiny by the cryosphere science community, we are now beginning to see evidence of potential marine ice sheet instability in this region,” said co-author Eric Rignot, chair, Donald Bren Professor and Chancellor’s Professor of Earth system science at UCI.

“The ice in West Antarctica has been melting faster in recent years, but the sheer size of Denman Glacier means that its potential impact on long-term sea level rise is just as significant,” he added.

According to the study, Denman Glacier experienced a cumulative mass loss of 268 billion tons of ice between 1979 and 2017.


Denman’s eastern flank is protected from retreat by a subglacial ridge. But Brancato said that the western flank, which extends roughly 4 kilometers, is characterized by a deep and steep trough with a bed slope conducive to accelerated retreat.

“Because of the shape of the ground beneath Denman’s western side, there is potential for rapid and irreversible retreat, and that means substantial increases in global sea levels in the future,” she said.

In December, Nature Geoscience published a paper on the BedMachine Antarctica project led by Mathieu Morlighem, UCI associate professor of Earth system science, which revealed that the trough beneath Denman Glacier extends 3,500 meters below sea level, making it the deepest land canyon on Earth.

The UCI and NASA JPL scientists report in the Geophysical Research Letters paper that the bed configuration of Denman is unique in Antarctica’s eastern sector. Other major glaciers, such as Totten and Moscow University, feature prograde beds that slope down in the flow direction, providing some measure of stability, Rignot said.


“We need to collect oceanographic data near Denman and keep an eye on its grounding line,” Rignot said. “The Italian COSMO-SkyMed satellite system is the only tool for us to monitor grounding line conditions in this sector of Antarctica, and we are fortunate to have on our team Dr. Brancato, who is skilled in extrapolating the data to give us the precise and up-to-date information we require.”

Sea level rise is just one of many dangers posed by our rapidly warming climate, but it’s one that presents massive difficulties. A huge portion of the global population lives close to sea level, along with infrastructure and industry. It’s almost certainly too late to stop the seas from rising for the rest of this century, though we might be able to slow that rate a bit. That means that we need to work out how to respond to it. Whether we try to build up cities to be able to continue existing where they are, regardless of sea level, or retreat from the water’s edge and rebuild at higher elevations, there’s a lot of work to be done. If we simply wait for the water to rise, and take a reactive, rather than a proactive approach, many people will die, resources will be lost, and the remains of cities and factories will pollute the waters they crumble into for decades to come, like sunken ships, but much, much bigger.

Climate change moves more slowly than a viral pandemic, but just as with COVID-19, there will come a time when the accumulated changes exceed the capacity of our existing infrastructure. We had a chance, until maybe the year 2000, to “contain” the problem, and to prevent catastrophe. Like with the American response to COVID-19, we blew that chance. We’re now in “flatten the curve” territory. We can reduce the rate of warming, and we can take measures to reduce the damage that warming does to our societies. The pandemic is showing us what a serious, global response to a crisis looks like. We need to take advantage of that, and push hard for things like the Green New Deal, and to take power away from the people who have, for decades, prevented action through corruption and misinformation.

Thanks to the COVID-19 outbreak, layoffs have increased, job interviews have been indefinitely postponed, and many places aren’t hiring new workers. All of that means I really need help paying my bills and keeping a roof over my head. Patreon.com is a way for you to help with that, even if it’s just a little bit, and get some perks and extra content in return. You control how much you give, and how long you give it, and every little bit really does help. When lots of people pitch in, it can make a huge difference. Please help if you’re able, and share my work with others. Thank you!


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