Hi - Tim Lenton is a great thinker and writer, but I imagine he might be the first one to say that arctic methane escape has not been his own area of expertise, and that more recent research such as the International Siberian Shelf Sudy (Gustafsson et al, 2008) or that of Shakhova, such as in Geophysical Research Abstracts, Vol. 10 (Shakhova, N. et al. 2008) are most significant and suggestive. The hydrates are becoming perforated, and clearly could become major tipping points very soon.
At the same time, I’ve been in touch with Euan Nisbet within the last few months, just when he was reporting to the UK parliament on the current European methane inventory, and this year’s natural CH4 emissions estimates. Arctic release certainly is not yet a major part of the global methane budget, and, as of a few months ago, I believe this year had not grown greatly over last year (I’m sorry I don’t have figures in front of me). So, this is why I have hesitated to sign John Nissen’s letter to Holdren in its current form (I'd be happy to sign if it is appropriately altered, by the way): while I think greatly increased research into SRM is absolutely vital, his letter makes it sound as though some such program should actually be undertaken as soon as possible, and is the only thing that can be done now – and that is flat out wrong-headed, I believe. I’ve posted before here about methane emissions. Simply put, the best, quickest way to staunch those increasing natural CH4 emissions is probably still at this point by rapidly reducing our own anthropogenic CH4 emissions. Despite talk of how cheap SRM can be (Keith, etc.), I think that over time the best value in total –RF/per $ could be shown to be methane emission reductions. A total of ~250B$ could lead to a decline of human emissions by about 33% (equal to some 60% of current global natural emissions), and while the change would certainly not be felt over months (taking fully ~15 yrs to reduce the methane RF by about 50%, and equal to about one quarter of the net human RF since industrialization), it demands no new research at all like geoengineering does, and the effects should begin to be felt within a few years of major emission declines. It would, of course, have zero negative side effects, gets more to the root of our problem than any geoengineering could, and should bring relief at a time scale commensurate with the current growth of the arctic problem, which is not taking place on a scale of months as of this time. It is further politically much easier to do than any comprehensive GHG policy or geoengineering, and it is utterly necessary that these emissions be cut as soon as possible in any case. Robert Watson, former head of the IPCC, started the Global Methane Fund during Copenhagen with much this same logic in mind. I would also like to mention something else. I think that there is a mistakenly simplistic faith in arctic SRM’s immediate effectiveness for the particular methane hydrate problem in the minds of Nissen and some others posting at this site. I believe I’ve written about this here before, without any response at all, but perhaps you would like to consider it: a comparison of Wieslaw Maslowski’s more volume-based ice modeling with that of others suggests that, if Maslowski is right, warm water getting in through the Bering Strait is worth at least a couple of decades of life for the summer arctic ice cover (i.e., the year when the minima is more than 80% reduced from the 20yr average, coming some decades earlier in his modelling than in most others). One can only imagine how important that warmer water coming in through the Bering Strait must be to the rapid destabilizing of the hydrates currently underway, which are on the bottom of the shelf not far from the Strait, compared to just the conditions at the surface above, which is the focus of most SRM plans. Thus, since the warmer water would still be coming in unimpeded and not need to travel very far, it could be that such "arctic SRM" plans will not be nearly as effective as hoped for this particular problem, at least not on a short time scale. That is why I suggested a project – probably much easier to see effectuated, in any case – to research the use of reflective floats just south of the Strait to help cool the waters as they are coming in. One year’s waste stream from the US alone of EPS and polyethylene should be enough to cover the area. I am certainly not suggesting that this idea could or should in any way replace sulfur-based or cloud albedo-enhancing approaches, but that it might be useful in any case to help deal with this most urgent question of methane hydrates, and seems like as good a place to start as any. Cheers, Nathan Nathan Currier 280 Ortman Rd. Greenwood, VA 22943 US 540.456.8544 -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
