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Ice Sheets in Greenland, Antarctica Could Reach Catastrophic ‘Tipping Points’ if We Don’t Limit Warming

Ice Sheets in Greenland, Antarctica Could Reach Catastrophic ‘Tipping Points’ if We Don’t Limit Warming
Scientists just gave us another terrifying reason to limit global warming to 1.5 degrees Celsius above pre-industrial levels: If temperatures push much beyond that point, both Greenland and Antarctica‘s ice sheets could reach a point where nothing can stop them from melting.

An international team of researchers published this chilling finding in Nature Climate Change Monday. The researchers set out to study how the ice sheets would fare in a warming world, and the results were urgent.

“A big take-away is that the ice sheets, like many components of the climate system, likely have tipping points. Once they reach a certain amount of warming (~1.5 – 2.0°C), positive feedbacks kick in and commit us to long-term ice sheet mass loss and sea level rise,” study author and Rowan University School of Earth and Environment Assistant Professor Luke Trusel explained on Twitter.

If these tipping points are tipped, it would be catastrophic for coastal communities and low-lying islands. The ice sheets combined contain enough water to raise sea levels by 65 meters (approximately 213 feet), according to a press release from the Netherlands Earth System Science Center (NESSC), one of the groups involved with the research.

To put that in perspective, this animation shows what the world would look like after just six meters (around 20 feet) of sea level rise.

Sea Level Rise Animation in Google Earth

Of course, all of that sea level rise wouldn’t happen at once. It would take several thousands of years for the Greenland ice sheet to disappear entirely and hundreds to thousands of years for the same thing to happen to the West Antarctic ice sheet.

But, as Trusel points out, it’s frightening to think that our inaction today could set things in motion that would persist so long after we are gone.

“These ice sheet instability mechanisms mean we are committed to sea level rise for centuries and millennia based on what we do now and in the very near future,” Trusel tweeted.

Besides, sea level rise is already causing problems for islands and coastal communities around the globe in the form of both more extreme storm surges and daily erosion and tidal flooding. Adding more would only increase the devastation.

Limiting warming to 1.5 degrees Celsius by 2100 wouldn’t stop sea level rise entirely, of course. Melting is already in motion and would likely continue at current rates until the end of the century, though researchers won’t rule out the possibility that those rates could still increase. But stopping our global fossil fuel binge at the 1.5 degree mark could be the difference between manageable difficulties and catastrophe.

Lead author and Université Libre de Bruxelles professor Frank Pattyn laid it out at the beginning of a Twitter thread explaining his research.

“It is important to limit global warming by 2100 to 1.5°C to maximise the chance of avoiding so-called tipping points that would dramatically accelerate mass loss from Greenland and Antarctic ice sheets,” Pattyn wrote.

Source: EcoWatch

By:  Olivia Rosane
Nov. 13, 2018 07:41AM EST



From NESSC – Netherlands:

Tipping points in Antarctic and Greenland ice sheets

The melting of the Greenland and Antarctic ice sheets will accelerate and become irreversible if global temperatures increase above a 1,5 – 2 degrees Celsius threshold, a newly published review of the world’s largest ice sheets finds. Even if the rise of global temperatures can be limited to 1,5 degrees Celsius by the year 2100, both ice sheets will continue to lose mass during this century, thereby contributing to an accelerating sea level rise. NESSC-researchers Michiel van den Broeke, Heiko Goelzer and Peter Kuipers Munneke contributed to the review paper, published in Nature Climate Change.

In their review of the behaviour of the two ice sheets in a warming world, the international team of scientists stresses the importance to limit global warming to maximally 1,5 degrees Celsius by the year 2100. This would lower the chances of crossing any tipping points of the ice sheets that would lead to a dramatic acceleration of ice loss – and subsequent sea level rise acceleration.

Sea level rise

Presently, the global sea level rises at a pace of nearly four millimetres per year. The melting of the Greenland and Antarctic ice sheets is becoming an increasingly important contributor to the already accelerating sea level rise. Both ice sheets together contain enough ice to rise global sea levels by roughly 65  metres.

The new review paper underlines that, even if anthropogenic warming of the global climate can be limited by 2100, the Greenland and Antarctic ice sheets will continue to lose ice during the course of this century. Likely, the ice loss will occur at rates similar to those observed over the past decade, however, larger ice loss rates cannot be ruled out, as large uncertainties in the future projections of the ice sheets remain. The review paper highlights some lingering key gaps in knowledge regarding climate forcing of the ice sheets and their resulting responses.

Tipping points

Notably, the researchers find that with warming above 1,5 – 2 degrees Celsius, both ice sheets are likely to cross tipping point thresholds, leading to irreversible mass loss. A complete disappearance of the Greenland ice sheet would occur over a period of several millennia due to increased melting of the ice sheet. For Antarctica, marine instabilities of certain sectors of the ice sheet, particularly in the West Antarctic ice sheet, would lead to multi-metre sea level rise on centennial to millennial time scales. The resulting sea level rise would have existential consequences for small island states and coastal cities across the world.

Frank Pattyn, professor at the Université libre de Bruxelles and lead author of the paper, says: “Limiting global atmospheric warming to 1,5 degrees Celsius will avoid short and long-term surprises from both ice sheets. It would also significantly reduce adaptation costs when global sea-level rise is limited – and not catastrophic.”

The Greenland and Antarctic ice sheets under 1.5 °C global warming
Pattyn, F., Ritz, C., Hanna, E., Asay-Davis, X., DeConto, R, Durand, G., Favier, L., Fettweis, X., Goelzer, H., Golledge, N.R., Kuipers Munneke, P., Lenaerts, J.T.M., Nowicki, S., Payne, A.J., Robinson, A., Seroussi, H., Trusel, L.D., Van den Broeke, M.
Nature Climate Change, 2018

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