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Modify energy fluxes to restore/enhance traditional Hudson Bay ice cover as contribution to sustaining Canadian permafrost and stored carbon


Description

Summary

The increase in atmospheric GHGs that has contributed to global warming has exerted an amplified influence on high latitudes, particularly through the amplification in solar heat uptake resulting from reduced snow and ice cover. Over land, the additional energy tends to remain near the surface due to the lower conductivity of vegetation and soils, such that once the seasonal loss of solar radiation starts, the land surface can cool rapidly. For water bodies, however, and particularly for Hudson Bay and large lakes in Canada and the Great Lakes, energy is being taken up and stored in these water bodies and then gradually given off through autumn and winter, thus tending to keep regional temperatures from dropping as low as in the past, and this has prevented permafrosted areas from being able to radiate away in the winter the extra energy added by both the CO2 increase and the reduced snow and ice cover.

This proposal would investigate the possibility for attempting to counteract at least some of this added warming influence, which has already initiated warming and some thawing of the region's permafrost and has the potential to cause release of very large amounts of carbon. While any release of carbon would tend to amplify global warming, if the release is a methane instead of CO2 and if the release is rapid instead of slow, activation of this natural carbon feedback could significantly amplify global warming.

There are at least two complementary approaches to modifying the energy balance of Hudson Bay (and possibly large lakes) that would be considered in the analysis: (a) enhancing the water body's loss of heat  in the fall and winter in order to enhance formation of reflective ice that would persist later into the spring and so also reduce uptake of solar radiation; and (b) increase the reflectivity of the open water, and perhaps also of over-lying low clouds, during the summer so as to reduce the uptake of solar radiation.


Category of the action

Geoengineering


What actions do you propose?

The primary effects of ice layers change over the course of the year. During sunlit periods, sea or lake ice, especially when covered by snow, increases surface albedo and so reduces uptake of solar energy. Enhancing ice persistence (e.g. by thickening the ice), extent, and reflectivity thus all tend to reduce energy uptake.

During fall and winter, when there is no or low sunlight, ice cover  insulates the water body, basically slowing loss of infrared radiation to the atmosphere by slowing the transfer of heat to the surface (that this is the case is why surface temperatures over extensive ice cover in the winter can dip well below -40 C while at the same time, just 1-2 meters through the ice, the underlying waters are at 0 C. Reducing this insulating effect would allow for greater loss of heat in the fall and winter. The reduced energy content of the system ends up being manifest in thickening of the ice. While thickening of the ice in the winter would reduce wintertime IR heat loss where it is not broken up, having thicker ice would result in it lasting longer into the sunlit season, which would mean a longer period during which at least more sunlight is reflected upward than by water.

As to potential useful approaches, the possibilities, used alone or in combination, would seem to at least include:

1. In that the ice is quite thin in the fall and early winter, it can be quite readily broken up by ice-breakers (powered by turbines instead of diesel engines to reduce soot generation) that would result in water at the freezing point rapidly losing heat to the atmosphere and creation of very cold water that would more readily form ice, thickening the ice layer.

2. As an alternative to ice breakers (which might be especially designed or equipped to break up more ice than is intended in slicing through the ice to gain passage), other possibilities might include floating, snow-making drifters that pump water from below onto the ice surface (heat being released to the atmosphere) and heat pumps, powered by the energy difference, that transfer heat from below to above the ice.

3. For brightening open waters during the sunlit season, microbubble generators might be towed by ships through the region or microbubbles might be released through land-based pipe systems. It might even be that injecting bubbles below the sea ice in winter would help increase the ice albedo.


Who will take these actions?

At present, the proposed approach is purely conceptual--it needs both rigorous scientific analysis and development (primarily with local, regional, and even global models as the atmospheric circulation could conceivably be modified), and engineering studies and development that would allow focused field experiments. At least initial field experiments would be on such a small scale (e.g., the size of a lake, and focused mainly on changes in energy fluxes that could be induced) that no more than local consequences would be expected. Because the proposed techniques essentially mimic natural processes, novel effects would not be expected nor persistence of effects beyond end of the experiment (e.g., no biological component that would persist over time).

Presuming positive outcomes of initial scientific and engineering analyses of potential implementation, expanded studies of the potential environmental, ecological, and societal implications would be needed. In that the intent would be to return the region to the type of wintertime conditions that have prevailed in the past, such analyses would have the advantage of being able to use past data and conditions to draw from in their analyses.

At the same time, consideration of local, regional, national, and international interests and considerations would need to be undertaken. Thus, everything from issues related to returning to a longer ice-in season for the ice with its potential beneficial influence on certain types of wildlife (e.g., polar bears) to issues of reduced rates of warming of permafrost and so of carbon loss would need attention. With the intent being to return to conditions of the recent past to which the system is adapted, there would seem to be a good chance that beneficial outcomes would prevail.


Where will these actions be taken?

With primary potential implementation over Canada and primary effects on the system (e.g., on winter and spring weather) expected over Canada and the US, a joint project by the scientific communities of these two nations would seem most appropriate, with the scientific community in other nations invited to be applying a critical eye to the analyses being done. 


What are other key benefits?

The first key benefit, if the approach works, would be to slow release of carbon from the permafrost carbon reservoirs of North America (and perhaps other regions of the Arctic might consider similar approaches) and thus to slow the pace of global warming, a benefit to all nations.

Other associated benefits would seem likely to include slower change of the North American meteorological environment, which would be beneficial to many types of flora and fauna (i.e., biodiversity), greater production of the cold air that has in the past been so important in determining the weather of North American Great Plains (and downwind areas).


What are the proposal’s costs?

Hudson Bay is approximately 4M sq km. Not all would need to be covered each year as the longer duration of ice would help to sustain itself by reducing solar uptake (and reduced summer albedo of open water would help too). So assume phase up over time to disrupting 1M sq km per year.

For coverage by a single icebreaker, a light ice-breaker (to break up thin ice--if ice is thick, problem is solved) going 30 km/hr for 150 days/yr (moving to thin ice as edge advances) that is designed to create a wake to break up ice over path 50 m wide, gives coverage of ~5000 sq km per season. So, would need ~200 icebreakers.

Very roughly, based on present construction costs, a heavy, multipurpose icebreaker costs about a billion dollars, so a light one might cost $300M and last over 30 years, so a capital cost of $10M per year. Double that to cover operation, so an individual icebreaker might cost $20M per year, which, together with the previous estimate, suggests a cost of $40K to disrupt a square km of ice per year. This would suggest a cost of perhaps $40B per year.

While this seems high, there would seem to be the potential for bringing the cost down. For example, by clever choice of the patterns of ship tracking given prevailing and predicted winds, it might well be possible to create sheets of ice that, driven by the wind, would collide with each other in ways that would cause fracturing of the ice over much larger areas than could be caused by a single ship track; or, it might be possible for two icebreakers to tow a chain between them that breaks up a much broader area than two ships could individually; or it might be that the very thin ice could be broken up by merchant ships that are used for very thin ice after the shipping season has shut down or that break up ice while on normal routes.

Costs of a pipe system with bubblers, etc. could be similarly estimated--it would be considerably less complicated than the types of irrigation systems that cover very large areas of land.


Time line

With a well-focused and adequately funded research program, an analysis of the possibility, potential, and value (benefits vs costs) should be able to be done over a 5-year period. Phased in consideration of ecological, environmental, societal, and governance issues might be adequately advanced over a similar period, in parallel with some focused field experiments. Building up to full operation might well take another decade or so, given need to build icebreakers.

Initial research tasks would need to include:

1. Model simulations of the effects of having thicker ice on Hudson Bay (and large lakes) for longer through the year on temperatures in the region--thus evaluate the underlying hypothesis that the additional heat taken up during the spring and summer due to melting back of the ice contributes to the increased thawing of permafrost.

2. Based on work of Seitz (2011), develop and evaluate possible use of bubbles (bright water)

3. Evaluate potential for augmenting effects of icebreakers


Related proposals

In terms of techniques that would be investigated and of the general types of impacts, the Climate CoLab geoengineering proposal to investigate slowing the loss of mass from the Greenland Ice Sheet is quite closely related to this proposal.


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, 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.

 

Seitz, R.: Bright water: hydrosols, water conservation and climatechange, Climatic Change, 105, 365–381, doi:10.1007/s10584-010-9965-8, 2011.