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 Tom Fiddaman Jan 29, 2013 10:15  |
It would seem that a much bigger downside is the degradation of the wetlands, which are already being degraded at unsustainable rates and will be adversely affected by climate and sea level impacts.
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 Ashwin Kumar Mar 4, 2013 12:13  |
Thanks for the proposal!
The first commenter raised the question of downsides. I'd be interested in knowing what you think of these.
As to efficacy of the proposed solution, draining wetlands could also increase surface temperatures – do you think this could inhibit the desired effect in some cases, for example by encouraging melting at greater depths?
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 Andrew Lockley Mar 5, 2013 01:20 | Proposal contributor
Draining wetlands will tend to increase summer temperatures but reduce winter temperatures, as the increased albedo and greater thermal conductivity/mass exert seasonal effects. Modified evapotranspiration will also increase temperatures when insolation is high, assuming similar vegetation cover.
Large scale biome modification is generally undesirable, but if the ecosystems are threatened by climate change, any consequential effect may be temporary or academic. Fuurthermore, the methane benefits to the global environment may outweigh the costs by habitat loss. this technique will need careful application to avoid inappropriate deployment.
Inundation as sea levels rise is a factor, and climate change will exert an albedo effect by shrinking coastlines. However, as most land mass is concentrated in continental interiors, this is likely a marginal effect.
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 Michael Maccracken May 2, 2013 05:18  |
While it would seem possible to make the approach work locally, it is not at all clear that it would scale up well at all, requiring basically requiring something like the re-plumbing of an area the size of a small continent.
An aspect not really covered might be whether doing this as the upper layer melts bight be able to create a dry insulating layer that could help keep the underlying permafrost cold. If indeed most precipitation occurs when it is cold, this might lead to good soil thermal conductivity during the cold winter months so heat could reach the surface and be emitted to space, and low thermal conductivity during the warm months due to how dry the surface material would be--and this would presumably slow the uptake of solar radiation that would warm the permafrost. This would all be nice if it would work.
Are there observational results for the variation in methane release through the seasons? Might this be of interest to get a sense of the likely removal rates and whether the additional emissions might impact atmospheric lifetime?
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Andrew Lockley May 3, 2013 04:22 | Proposal contributor
Draining at a large scale can be done relatively easily. The Dutch and English have reclaimed much of their low-lying farmland from saltmarsh in this manner. Essentially all water ultimately ends up in major rivers, and lowering the level of these rivers artificially has a knock-on effect right up the watershed. This can be achieved using a tidal barrage, or with pumps. Further upstream, the creation of a small number of large, artificial drainage ditches can cut through slow-flowing reedbeds, etc. - providing rapid drainage which lowers the water table dramatically. Saddam Hussein used this technique to destroy the Marsh Arabs' lands.
As I understand, methane is released generally in the warmer months, when permafrost is melting.
I am unable to comment on how the water level affects heat transfer through permafrost. I imagine it's not simple.
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 2013geoengineeringjudges 2013geoengineeringjudges Jul 10, 2013 02:36 |
Thank you for sharing your ideas and for the work invested to create this proposal. Your proposal has been considered carefully by the judges, and while the proposal has interesting ideas, and we appreciate the response to questions that were raised, there are some types of issues that are critical to the proposal as it is formulated. You have raised some of them in your proposal, and this discussion is appreciated. However, more specific answers to the questions on which the efficacy of the scheme would depend and consequently of the magnitude of the impact this could have would have strengthened the proposal and made a stronger case for the feasibility of the scheme. Second, while you acknowledge that draining wetlands would have adverse local effects, more discussion on the governance of intervening in wetlands for global benefit (whose magnitude is uncertain) seems critical to this proposal.
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