September 27th, 2018 by Steve Hanley
John Moore is a scientist at Beijing Normal University in China and a professor of climate change at the University of Lapland in Finland. Michael Wolovick is a researcher in the Department of Geosciences at Princeton. Together they have completed a new study entitled “Stopping the flood: could we use targeted geoengineering to mitigate sea level rise?” It is published in the current issue of Cryosphere, the official journal of the European Geosciences Union.
Here is the abstract of the study:
“The Marine Ice Sheet Instability (MISI) is a dynamic feedback that can cause an ice sheet to enter a runaway collapse. Thwaites Glacier, West Antarctica, is projected to be the largest individual source of future sea level rise and may have already entered MISI.
“Here, we use a suite of coupled quasi-2-D ice–ocean simulations to explore whether targeted geoengineering using either a continuous artificial sill or isolated artificial pinning points could counter a collapse. Successful interventions occur when the floating ice shelf regrounds on the structure, increasing buttressing and reducing ice flux across the grounding line. Regrounding is more likely with a continuous sill that is able to block warm water transport to the grounding line. The smallest design we consider is comparable in scale to existing civil engineering projects but only has a 30% success rate, while larger designs are more effective.
“There are multiple possible routes forward to improve upon the designs that we considered, and with decades or more to research designs it is plausible that the scientific community could come up with a plan that is both effective and achievable. While reducing emissions remains the short-term priority for minimizing the effects of climate change, in the long run humanity may need to develop contingency plans to deal with an ice sheet collapse.”
The Thwaites glacier, which is about the size of Florida, is the largest on Earth. “Thwaites could easily trigger a runaway [West Antarctic] ice sheet collapse that would ultimately raise global sea level by about 3 meters,” Wolovick tells Science Daily. “The most important result [of our study] is that a meaningful ice sheet intervention is broadly within the order of magnitude of plausible human achievements.”
Building columns of rock and sediment to support the ice above would require about 1.5 cubic kilometers of material to be placed on the ocean floor beneath it. For comparison purposes, the excavation of the Suez Canal required the movement of about 1 square kilometer of material. But Moore cautions that project has only a 30% chance of success.
Building a complete shelf under the ice would have a 70% chance of success and be the largest engineering project in history. Not only would it support the ice above, it would also divert warmer water away from the underside of the glacier. If everything worked perfectly, such a plan might actually enable the formation of new ice. Projections are that the underwater seawall would preserve the glacier at least partially for 1000 years, the limit of how far into the future current software can predict.
Slowing down the melting of the Thwaites glacier would allow coastal regions more time to prepare for rising sea levels, but both scientists agree the world is not ready for such an ambitious project. Because of the harsh climate in the Antarctic, much more preliminary engineering work needs to be done before such an effort could begin. They are hopeful their report will spur other scientists to add their own input to refine the plan.
“We all understand that we have an urgent professional obligation to determine how much sea level rise society should expect, and how fast that sea level rise is likely to come. However, we would argue that there is also an obligation to try to come up with ways that society could protect itself against a rapid ice-sheet collapse,” says Wolovick.
Both Moore and Wolovick are quick to point out that their plans are virtually worthless unless the world also drastically reduces carbon emissions. They are also well aware of the professional climate deniers who will attempt to use their research to argue there is no climate emergency and humanity will somehow find a way at the last possible moment to “science our way” out of the full fledged climate emergency that lies ahead.
“There are dishonest elements of society that will try to use our research to argue against the necessity of emissions’ reductions. Our research does not in any way support that interpretation,” they say.
Not only would reducing emissions help slow down melting of glaciers, it would also lower ocean acidification, coastal flooding, droughts, and heat waves. Failure to do so will reduce the chances that any engineering solutions will be successful. “The more carbon we emit, the less likely it becomes that the ice sheets will survive in the long term at anything close to their present volume,” Wolovick says.
A larger question is, who would undertake any such glacier rehabilitation schemes? Any one of them would require unprecedented international cooperation, something the United States seems to have absolutely no interest in doing so long at the present time. By the time the US gets around to supporting such initiatives, it well may be too late not only for America but the world at large as well.