The flow of Greenland’s glaciers toward the sea may have increased significantly in the past decade, but a new report in Nature finds that rate of increase is unlikely to continue. “The loss of ice has doubled in the past 10 years, but it’s not going to double again,” said lead author Faezeh Nick, a glaciologist at the University Centre in Svalbard, in Longyearbyen, Norway, in an interview.
That conclusion, based on a new, sophisticated computer model, makes the worst-case scenario of sea level rise — an increase of 6 feet or so, on average, by 2100 — look less likely to play out.
That’s the good news. The bad news is that, in the model at least, the slowdown doesn’t necessarily bring glaciers back to their original, stately rate of flow. And since the heat-trapping gas that has already put into the atmosphere will be there for hundreds of years to come, Greenland will continue to melt indefinitely. The fact that it may not happen quite as fast as the worst-case scenarios might forecast isn’t all that reassuring.
Because even if sea level goes up by only half that much, the combination of rising seas and periodic storm surges could devastate coastal areas around the world. Scientists have concluded, based on earlier studies, that the lower figure of about 3 feet is most likely, and while that research didn’t explicitly calculate anticipated sea level rise, it appears consistent with those estimates.
Earlier studies, based on satellite observations, had also noted that Greenland’s ice flow has started to slow, which means the dumping of icebergs into the ocean should slow as well. Projecting what’s likely in the future, however, is the province not of observations but of models. In this case, Nick and a half-dozen colleagues used a new model that factors in the effects of climate change on both the air above Greenland and on the ocean below.
Those effects, Nick said, depend on the characteristics of individual glaciers. The Petermann glacier in northwest Greenland, for example — one of four the scientists modeled — “has a very long floating shelf, so it’s very sensitive to ocean warming.” As a result, the Petermann has loosed two massive “ice islands” into the sea, one in 2010 that was four times the size of Manhattan, and another, about half as big, in 2012.
But while those were major events, they didn’t affect the Petermann’s overall flow rate significantly. Other glaciers, such as the Jacobshavn, respond to warmer seas not just by letting loose big chunks of ice, but also by flowing more quickly. The reason: Jacobshavn’s ice was mostly grounded on the sea floor, not floating, creating tremendous friction that kept the upstream parts of the glacier in check. When that grounded ice is removed, it’s as though the brakes suddenly came off.
Warmer air temperatures, meanwhile, melt ice on top of the glaciers, and on the massive ice sheet they flow out of. In the summer of 2012, in fact, for the first time in more than a century, virtually the entire surface was at least partially melting for a few days in July (the reason, some scientists believe, was not just warmer-than-normal air temperatures overall, but also the heat-trapping effect of thin clouds).
Eventually, all of this water flows to the sea, but along the way it funnels down into crevasses in the ice, which can help lubricate the ice-rock interface at the bottom, letting glaciers flow faster. Downflowing water can also widen cracks in the ice, Nick said, which can enhance disintegration of the glacier’s leading edge already weakened by the warming ocean.
Feeding all of these effects into their model, the scientists found that speedup in the flow of glaciers into the sea is something to be expected in a generally warming climate, but that it won’t simply get more and more pronounced. “You see a big jump,” Nick said, “and then it slows down again.”
CORRECTION: A previous Climate Central headline incorrectly suggested the study reported current melting observations, rather than future projections.
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.