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Accelerated calving of the Jakobshaven ice stream in Greenland is caused by heat from warmed waters from Labrador Sea that could be cooled


Description

Summary

Loss of ice mass from Greenland glacial ice streams has been accelerating, apparently mainly as a result of heat transfer from the warming ocean waters in the fjords into which the ice streams flow. The warmed waters tend to be coming in up to a few hundred meters below the surface, with fresher (so less dense) relatively cold waters (containing glacial melt water) flowing out above.

To slow the rate of heating of the ocean-ice stream interface, this proposal seeks to evaluate several approaches that might be used so that the loss of ice mass from Greenland can be reduced. Among others (and further ideas would be sought and evaluated), the approaches that would seem worthy of investigation for use alone or in combination would seem to be:

A. Actions that would attempt to counter the loss of duration of sea ice cover that is occurring in, and so uptake of heat by the waters of, Baffin Bay, Davis Strait, and the Labrador Sea. This might be accomplished by, for example, brightening marine stratus clouds over this region during the summer by injection of cloud condensation nuclei; using ice breakers to break up the sea ice in fall and winter so as to increase loss of ocean heat via IR radiation from the surface; injection of bubbles from ships or deployment of reflective objects to enhance surface albedo, or via other means.

B. To reduce the flow of warmed (say 2 C) waters that flow into the fjords and transfer their heat to the face of the ice stream or heat it from below. Approaches to reducing this heat flow might include using wind- or wave-powered pumps to vertically mix overlying cold waters with underlying warmer waters in the inflow areas to the fjords; and/or creating an underwater weir at the inflow to the fjord that would act as a dam to the denser underlying waters while below the depth that would be pushed out of the way by the outward-moving icebergs (e.g., such a weir might be created by piling up large Kevlar bags filled with nearby sediment)


Category of the action

Geoengineering


What actions do you propose?

The proposal is to carry out a research program that would evaluate the potential for such an approach to significantly reduce the flow of heat from the adjacent water bodies that is reaching the face of the glacial streams and thus contributing to accelerated calving. With the potential that the Greenland ice sheet could contribute significantly to global sea level rise over the 21st century and beyond, exploring all possibilities for slowing the loss of ice mass would seem to be an appropriate area of study. Recognizing that the relatively dim prospect of limiting warming at the global scale and the low likelihood of any near-term global-scale geoengineering that would be sufficient to slow loss of ice mass from Greenland, it would seem well worth exploring regional options.

Simultaneously, it might well be productive to also have the project consider whether the indicated approaches or others that might be suggested might be applicable to slowing the loss from ice streams and glacial faces draining the Antarctic Ice Sheet as well as the Greenland Ice Sheet. Given the very large potential rise in sea level and coastal damage and prospects that lie ahead, exploration of all potential approaches would seem to be desireable.


Who will take these actions?

There are a number of possibilities for taking leadership of the required research and analysis effort. For example, the members of the Arctic Council might organize a focused/directed project looking toward potential implementation while the CliC programme of the WCRP organizes efforts to  support baseline research that would be needed to underpin the overall focused/directed component of the effort. Alternatively, the EU or the USGCRP could organize such a project--the key is that it be directed to evaluate and if possible come up with a plan in a finite time (e.g., five years) as time is of the essence. 


Where will these actions be taken?

The research program would take place in scientific laboratories with any necessary field testing going on in the area of Baffin Bay, Davis Strait, and the Labrador Sea, so would be done under the auspices of Canada and Denmark.


What are other key benefits?

In addition to evaluating the potential for slowing the loss of ice mass from the Greenland (and possibly) and Antarctic ice sheets and so slow the rise in global sea level, cooling the adjacent seas would possibly help in sustaining regional cooling (see the separate proposal for seeking to slow warming of the Canadian shield region to slow permafrost warming and thawing).

Restoring the sea ice of the region would also be a benefit to the marine life and marine mammals of the region and therefore a benefit to the region's Indigenous Peoples. Generally, the reduction of heat gain in the region would also help, in a modest way, to slow global warming.


What are the proposal’s costs?

As this is a research program, its costs would be quite modest. A directed research program of several tens of millions of dollars per year for of order five years would likely be what would be needed at the start. Assuming that the scientific and analytic studies are successful, initial field testing would likely require a few hundreds of millions of dollars, and then full implementation would be in the range of perhaps a few tens of billions per year. Were the approach to be successful in limiting loss of ice from Greenland while global emissions are brought under control, the decreased likelihood of potentially crossing the potential tipping point of triggering the virtually complete loss of Greenland's ice sheet over a couple of centuries would be well worth the investment given the tremendous amount of coastal infrastructure at risk.

While thus seeming likely to overall be a worthwhile project to investigate and even implement, a full cost analysis would of course be part of the research effort.


Time line

Given the accelerating pace of loss of ice from the Greenland (and Antarctic) Ice Sheet, a focused and clearly directed program should be undertaken, setting a goal of having a then testable approach within five years. Assuming success, initial full-scale field testing of approaches could likely be achieved over the next five years, with full build up and implementation occurring over the succeeding ten-year period. The longer the project takes, the less likely that a successful approach will be identified and the greater the likelihood of really significant sea level rise over the 21st century and beyond.


Related proposals

In terms of the types of techniques that might be used, the Climate CoLab proposal to slow warming of northern North America as a way to slow the thawing of permafrost and onset of the natural carbon cycle is relatively closely related.


References

 

MacCracken, M. C., 2011: Potential Applications of Climate Engineering Technologies to Moderation of Critical Climate Change Impacts, IPCC Expert Meeting on Geoengineering, 20-22 June 2011, Lima, Peru, pages 55-56 in Meeting Report, edited by O. Edenhofer, R. Pichs-Madruga, Y. Sokona, C. Field, V. Barros, T. F. Stocker, Q. Dahe, J. Minx, K. Mach, G.-K. Plattner, S. Schlömer, G. Hansen, and M. Mastrandrea, Intergovernmental Panel on Climate Change, Geneva, Switzerland.