News from Antarctica has been unsettling for quite some time. And this week, as reported by Bob Berwyn at Inside Climate News, we got some more. The basic message of two new studies is that the melting ice situation in Antarctica is likely worse than scientists short on adequate data had previously thought. No, this isn’t going to affect anybody’s summer plans. But it’s more evidence that markedly higher seas are probably not centuries away.
The author of one of the studies, Rachel Diamond, characterized last year’s steep plunge of 770,000 square miles below the average amount of Antarctic sea-ice as a 1-in-2,000-year event. It wouldn’t have happened without climate change, she said. “Anything less than one-in-100 is considered exceptionally unlikely.”
Using new satellite data, researchers in the other study—published in the Proceedings of the National Academy of Sciences—found that jets of warm saltwater are plunging as far as 6 kilometers (3.7 miles) beneath a floating ice shelf of the gigantic Thwaites outlet glacier in West Antarctica. That tongue of ice flexes and bends with the tide allowing the water intrusion and exposing what long ago was nicknamed the “doomsday glacier” to what the researchers call “vigorous melting.”
It gets that name because if it melted entirely, that alone would add about 60 centimeters (2 feet) of global sea level rise. But if it did all melt, that would allow a speed-up in the melting of the whole West Antarctic Ice Sheet, a melt that is already inevitable. If the entire ice sheet were to melt, that would add another 3.3 meters (11 feet). But, as Jeff Goodell noted in his book last year, The Heat Will Kill You First.
The Thwaites study’s lead author, Eric Rignot, a scientist with the University of California at Irvine, told Chris Mooney at The Washington Post: “The water is able to penetrate beneath the ice over much longer distances than we thought. It’s kind of sending a shock wave down our spine to see that water moving kilometers.”
It’s just awesome what it does to my spine when a climate scientist says something revealed in their research gives their spine a jolt.
The worry is that pressurized saltwater intrusions are getting under or around the ice at the grounding edge where the glacier is tethered to the land behind the ice shelf. That would expose a much larger portion of the glacier to ocean water, hollowing it out.
Asked how fast the entire glacier could melt, Rignot told USA Today: "It will take many decades, not centuries. Part of the answer also depends on whether our climate keeps getting warmer or not which depends completely on us and how we manage the planet."
According to an article in Science Daily:
For decades, Rignot and his colleagues have been gathering evidence of the impact of climate change on ocean currents, which push warmer seawater to the shores of Antarctica and other polar ice regions. Circumpolar deep water is salty and has a lower freezing point. While freshwater freezes at zero degrees Celsius, saltwater freezes at minus two degrees, and that small difference is enough to contribute to the "vigorous melting" of basal ice as found in the study.
Co-author Christine Dow, professor in the Faculty of Environment at the University of Waterloo in Ontario, Canada, said, "Thwaites is the most unstable place in the Antarctic and contains the equivalent of 60 centimeters of sea level rise. The worry is that we are underestimating the speed that the glacier is changing, which would be devastating for coastal communities around the world." [...]
"At the moment we don't have enough information to say one way or the other how much time there is before the oceanwater intrusion is irreversible. By improving the models and focusing our research on these critical glaciers, we will try to get these numbers at least pinned down for decades versus centuries. This work will help people adapt to changing ocean levels, along with focusing on reducing carbon emissions to prevent the worst-case scenario."
As always, scientific reserve mandates a don’t-jump-to-conclusions-without-more-data approach. Other scientists say there’s a lot more to learn before any impacts from this added melting factor in the Antarctic should be included in climate computer models. Rignot is in total agreement with the need for more research. But he’s also eager to get more data plugged into the models. Berwyn reports:
“The important thing about Antarctic sea ice is that since 2016, it has changed state,” [Rignot] said.
Some papers have explained last year’s sea ice decline as an abrupt event, but Rignot has a different perspective.
“I see it as Antarctic sea ice evolving very, very slowly for decades, and now it has reached a threshold,” he said. “It’s an illustration that the Southern Ocean is changing. Remember that the loss of Antarctic sea ice just since 2016 is bigger than the loss of Arctic sea ice in all of the last 40 years combined. It’s kind of a big deal.”
It’s too bad that a threshold of change has yet to be reached by all-too-many of our supposed political leaders. It’s not just Donald Trump who hunts for campaign cash with vows of policy favors for the fossil fuel barons. It may seem like a long way from the Thwaites Glacier to Mar-a-Lago and the oil- and gas-rich shale of the Permian Basin, but they are as tightly linked as the carbon dioxide and hydrocarbon chains being pumped into the atmosphere.
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