By Mike S Payton, Contributing Reporter
MIAMI BEACH, FLORIDA – A team of researchers at Massachusetts Institute of Technology (MIT) in Cambridge, MA, have published a report that finds even the tallest ice cliffs should support their own weight rather than collapsing rapidly. This may mean that the ice cliff contribution to sea level rise could be slower than some worst-case predictions.
Antarctica’s ice sheet in the Southern Ocean spans nearly twice the area of the contiguous United States, and massive, floating ice shelves extend hundreds of miles out from it. When these ice shelves collapse into the ocean, they expose towering cliffs of ice along Antarctica’s edge.
“The current worst-case scenario of sea level rise from Antarctica is based on the idea that cliffs higher than 90 meters would fail catastrophically,” Brent Minchew, assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences told MIT News.
“We’re saying that scenario, based on cliff failure, is probably not going to play out. That’s something of a silver lining. That said, we have to be careful about breathing a sigh of relief. There are plenty of other ways to get rapid sea level rise.”
One example of other threats is the recent finding by researchers that so-called ‘upside-down rivers’ of warm ocean water which have not been included in forecasts.
“Warm water circulation is attacking the undersides of these ice shelves at their most vulnerable points,” said glaciologist Karen Alley, visiting assistant professor of Earth Sciences at The College of Wooster in Ohio.
However in terms of the MIT finding, which was published in Geophysical Research Letters yesterday (October 21st), results suggest that the Earth’s tallest ice cliffs are unlikely to collapse catastrophically and trigger a runaway ice sheet retreat.
“Ice shelves are about a kilometer thick, and some are the size of Texas,” says MIT graduate student Fiona Clerc. “To get into catastrophic failures of really tall ice cliffs, you would have to remove these ice shelves within hours, which seems unlikely no matter what the climate-change scenario.”
Clerc clarified that this is not salvation from the base predictions, “Our results do not rule out the 2-feet projection from the IPCC because those projections do not take into account the marine ice cliff instability (MICI).”
“The implications of our results are more focused and suggest that a worst-case scenario (not part of the 2-feet projection) involving the collapse of West Antarctica due to the cascading brittle failure of ice cliffs (by MICI) may not play out.”
This research was supported, in part, by the National Science Foundation. Fiona Clerc is the lead author of the new paper, along with Minchew, and Mark Behn of Boston College.
Clerc concluded, “The next step in this research is to confirm the theory presented here with observations of ice cliff deformation.”
Adding that, “The solution to mitigating sea level rise remains the curbing of greenhouse gas emissions.”