Hi Nathan, Thanks for that thoughtful posting. I am sorry you have the impression that AMEG might be proposing cloud brightening as a silver bullet. We obviously have a strong advocate of that particular method in Stephen Salter, who is a member of the group. But Stephen recognises that we have an emergency situation because of the rapidity of sea ice retreat, with a possible collapse of sea ice extent this summer. So measures have to be taken quickly, ideally within the next few weeks. Stephen is considering having the spray for cloud brightening on land (e.g. Faroes) rather than on ships. But, even with government backing, this might still take a year or two to get going. Meanwhile we have to think of measures that could be taken more quickly. At least we have to avoid unnecessary heating. Obviously we must avoid "termination" effects - particularly the warming that will happen if/when they start to remove sulphur from ship fuel. Stephen quoted a figure of -0.6 Watts/m-2 from that, if I remember. Anyway ships have a surprisingly large cooling effect!
But your idea of deliberately adding sulphate aerosol to the troposphere at appropriate locations might be something which could be implemented very quickly as a temporary measure band-aid, so has to be on the table. And if this has the effect of suppressing methane in wetlands (a major contributor to the methane level in the atmosphere), so much the better. BTW, as engineers, we are seeking to obtain a cooling effect of the order of half a petawatt into the Arctic to halt the sea ice retreat. Cheers, John On Sun, Mar 18, 2012 at 6:28 AM, Nathan Currier <natcurr...@gmail.com>wrote: > Thanks for the responses - though what I had in mind was actually more > in line with the tenor of Mike's latest comments about the 6-to-1 > lifetime ratio for arctic sulfur SRM, stratospheric vs. tropospheric, > etc. > > David’s early article is very impressive for how much it adumbrated > the current public discourse on geoengineering, though at the same > time, a bit of misunderstanding about what I was intending to ask – > and I was probably not expressing myself very well – possibly > underscores how something really has been shifting lately within the > geoengineering world, too. What I meant about tropospheric sulfur > injections was entirely in the newer sense of a more ‘localized > geoengineering’, which has been getting attention here in this group > lately (so much so that I forgot to mention what I meant in my > question), and which I think makes a world of difference in > considering its use. In a sense, stratospheric injections can’t be > effectively localized, and this newer local thinking - coming in > response to events on the ground - might bring out new ways of > considering tropospheric sulfur versus stratospheric sulfur, as Mike’s > comments from earlier today in that other thread show, and the issue > of sulfur's dangers, which are the main point in David's comments, are > clearly altered by the reduced scale of use. > > In the BBC article that Andrew has just posted, Pete Wadhams is > talking about AMEG’s plans should the methane situation there > deteriorate a good deal further (which seems almost certain, if I had > to guess), and they focus on MCB alone. I think I had first seen > mention here of tropospheric sulfur injections in this context from > Mike, and this really took off in my imagination when I by chance > shortly afterward saw some work involving Eileen Matthews (Gauci et > al) showing how strongly just ordinary levels of acid rain will impede > methanogenesis in wetlands, with strong reductions, like 40% or so, > which play out through considerably longer time periods than the brief > atmospheric lifetime of the aerosols. > > I think study of this combined methane-SRM effect for tropospheric > sulfur injection should really be done. Curiously, David, in what you > sent me, the abstract on intercontinental effects of SO2 don’t suggest > that Russia is particularly bad for that particular concern, less so > than Europe, for example. And curiously, I might add, despite what you > just wrote, in your early paper you had actually listed stratospheric > injections as more dangerous than tropospheric (although I assume for > entirely different reasons, related then to ozone loss concerns, etc). > > But this is really something very different now from all that, or from > Budyko’s early comparisons of efficiency, lifetimes, etc. We’re > talking about a very limited area for treatment, almost nothing by > comparison with plans to geoengineer a global –1W/m2 or some such > thing. And currently one third of the land area of China is > experiencing acid rain, I recently read. How could it be acceptable to > add copious amounts of sulfur to one of the most densely populated > parts of the planet, which will clearly lead to considerable mortality > and sickness, and unacceptable to add any sulfur at all to a mostly > unpopulated area around the mouth of the Lena river, where there are > globally dangerous submarine methane hotspots and lots of wetlands, > thermokarst lakes, etc, emitting plenty of methane right nearby? > > Could one not hope that there might be some effect from the sulfur on > the shelf floor itself, too? (I've cc-ed Vincent Gauci on this, and > maybe he could easily answer that). After all, it is a complex > picture at the ESAS, probably with older methane stores and current > methanogenesis from thawing submarine permafrost driving the ambient > methane levels' rise there together. Indeed, the isotopic analysis > thus far points more to contemporary methane, which might > realistically be capable of being impacted – so it might be possible > to help push back against this spiraling situation in multiple > respects at once simply through tropospheric emissions of sulfur. That > is, with pinpointed and targeted ground level injections, there’s the > scattering effect – less efficient than in the stratosphere but still > certainly present – then the indirect effect (its ‘Twomey’ effect), > and then its methane-suppressing effects as well. Someone should try > to roughly calculate what might be possible totals in terms of local – > RF, given different options for release area, amount of release per > hour, estimates of what the wetlands near the hotspots are currently > emitting, etc. > > Further, since it sounds from the BBC article as though MCB is the > main thing being considered by AMEG right now, another question of > mine would be for John, and that is how would the interaction of such > ground-level sulfur injection and the MCB compare to the rather > synergistic situation of MCB with stratospheric injections? (I noticed > that Wadhams is proposing MCB down around the Diomedes, though). I > realize that’s probably got to be a complex answer. > > In terms of the sulfur’s dangers, like Paracelsus’ old saying, “The > poison is the dose.” The US still emits about 2/3rds of the SO2 it did > back in 1980, but mortality here has, I believe, been lowered a great > deal more than a third (I couldn't find current numbers for US deaths > from sulfur pollution, though). Obviously, as David himself pointed > out, since it would be done explicitly for its RF effect, too, there > would be a good deal of capacity to control its releases to prevent > harm from taking place as much as possible (although there are always > going to be temporary negative ecological impacts, I realize, too). > > I would gather it would also be much easier to bring such a plan to > deployment, in terms of governance issues, public acceptance, etc, > than anything done involving the stratosphere. > > All Best, Nathan > > > > On Mar 17, 8:43 am, Veli Albert Kallio <albert_kal...@hotmail.com> > wrote: > > The size of the termination shock is likely to be comparable to the > graph when temperatures were suppressed from 1940-1970 when sulphur > emissions were rising. The acid rains were starting to destroy forests (the > Black Forest in Germany) and the acidity of Sweden's and Finland's lakes > were rising rapidly. UK had western winds that pushed most of sulphur into > Sweden and some of it to the Baltic countries and Finland. Nickel and > Murmansk industries in the Arctic caused widespread dead zones in the Kola > Peninsula, in Russia that lies north-east of Finland. The quantity > increases of sulphur may have occurred, but it would push the warming 30 > years ahead of schedule if we follow figures from 1940-1970. Events that > could lead to a sudden switch off of energy system using sulphur fuels > could be a nuclear war or event like sudden Greenland ice sheet land > containment failure leading to Heindrich Ice Berg Calving Event and the > North Atlantic Ocean to be filled by broken ice bergs and the onset of the > Last Dryas. However, both nuclear winter and the Last Dryas would mitigate > the warming effect by strong negative feedbacks in either scenario. A > sudden sea level jump by few metres would also tear off ice shelves by > bending them loose around Antarctica. This replicates the cooling of > Northern Hemisphere to the Southern Hemisphere. Droughts would be > unbearable in both cases as the oceans would be very cold while the global > dimming effect would be lost over the continent. The Atlantic regions would > be affected by cold and drought, and much of eastern parts of Eurasia would > suffer loss of monsoon and very low precipitation. Large ice bergs resulted > in above kind of event are so-called ice islands and these can take 15 > years to melt away. During this period the ocean remains perennially cold > and may be Finland could re-introduce its reindeer and musk ox stocks > across the mainland Europe to supply meat. As a positive point the Central > Europe could enjoy a period of beautiful Arctic flowers such as Dryases > that like the cold weather and decorate our Arctic summer each year. > Regards, Albert > > Date: Sat, 17 Mar 2012 09:59:10 +0000 > > Subject: RE: [geo] tropospheric aerosol use > > From: and...@andrewlockley.com > > To: john.latha...@manchester.ac.uk > > CC: natcurr...@gmail.com; geoengineering@googlegroups.com; > bala....@gmail.com > > > > Another point to note is that tropospheric sulfur geoengineering is > already being done, albeit inadvertently, by power plants, ships and > factories. > > If we stop this, we will have a termination shock, as was reported > numerically on this list recently wrt the US (possibly by Kens group). > > A further termination shock will arise from secondary effects on marine > clouds. This was reported at IUGG, but observationally rather than > numerically. I've not seen the paper. > > We are therefore just about to commence a poorly researched > geoengineering programme to heat up the planet a bit! > > A > > On Mar 17, 2012 3:53 AM, "John Latham" <john.latha...@manchester.ac.uk> > wrote: > > > > Hello All, > > > > Budyko’s points – re tropospheric vvs stratospheric aerosol - reiterated > > > > by Govindasamy Bala (below), in response to Nathan Currier’s question > > > > (also below) are clearly valid vis-à-vis cooling via scattering of solar > > > > radiation and concomitant global cooling. > > > > However, it does not follow that the effectiveness of stratospheric > seeding is > > > > greater than that of the Marine Cloud Brightening (MCB) geo-eng > technique, > > > > which involves the (tropospheric) seeding of marine stratocumulus clouds > > > > with sea-water aerosol, in order to increase their droplet number > > > > concentration, and therefore their albedo (with concomitant global > cooling). > > > > Latham et al (2008) presented arguments indicating that the ratio of the > rate of > > > > planetary radiative loss to required operational power is very large (in > the > > > > range 10**5 to 10**7 according to the type of vessel used for the > continuous > > > > spraying required). They pointed out that the main reason why this ratio > is so > > > > high for MCB is that Nature provides the energy required for the > increase of > > > > surface area of newly activated cloud droplets by 4 or 5 orders of > magnitude > > > > as they ascend to cloud top and reflect sunlight. > > > > All Best, John. > > > > John Latham > > > > Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 > > > > Email: lat...@ucar.edu or john.latha...@manchester.ac.uk > > > > Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 > > > > or (US-Cell) 303-882-0724 or (UK) 01928-730-002 > > > > http://www.mmm.ucar.edu/people/latham > > > > ________________________________________ > > > > From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] > on behalf of Govindasamy Bala [bala....@gmail.com] > > > > Sent: Friday, March 16, 2012 3:52 AM > > > > To: natcurr...@gmail.com > > > > Cc: geoengineering > > > > Subject: Re: [geo] tropospheric aerosol use > > > > "Climate changes" by Budyko, on page 244, discusses why tropospheric > aerosols are not as effective as stratospheric aerosols for climate > modification. > > > > 1) life time is only a couple of weeks > > > > 2) Particle size becomes too big quickly and hence not effective for > scattering > > > > 3) Presence of clouds make them less effective > > > > 4) absorption by aerosols of near IR shortwave could partially cancel > the cooling by scattering. > > > > Bala > > > > On Thu, Mar 15, 2012 at 9:53 PM, Nathan Currier <natcurr...@gmail.com > <mailto:natcurr...@gmail.com>> wrote: > > > > Does anyone know of any published papers exploring the use of > > > > tropospheric aerosol use? > > > > cheers, > > > > Nathan > > > > -- > > > > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > > > > To post to this group, send email to geoengineering@googlegroups.com > <mailto:geoengineering@googlegroups.com>. > > > > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com<mailto: > geoengineering%2Bunsubsc r...@googlegroups.com>. > > > > For more options, visit this group athttp:// > groups.google.com/group/geoengineering?hl=en. > > > > -- > > > > Best wishes, > > > > ------------------------------------------------------------------- > > > > Dr. G. Bala > > > > Associate Professor > > > > Center for Atmospheric and Oceanic Sciences > > > > Indian Institute of Science > > > > Bangalore - 560 012 > > > > India > > > > Tel: +91 80 2293 3428 > > > > +91 80 2293 2075 > > > > Fax: +91 80 2360 0865 > > > > +91 80 2293 3425 > > > > Email: gb...@caos.iisc.ernet.in<mailto:gb...@caos.iisc.ernet.in> > > > > bala.gov<http://bala.gov>@gmail.com<http://gmail.com> > > > > Web:http://caos.iisc.ernet.in/faculty/gbala/gbala.html > > > > ------------------------------------------------------------------- > > > > -- > > > > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > > > > To post to this group, send email to geoengineering@googlegroups.com. > > > > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > > > > For more options, visit this group athttp:// > groups.google.com/group/geoengineering?hl=en. > > > > -- > > > > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > > > > To post to this group, send email to geoengineering@googlegroups.com. > > > > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > > > > For more options, visit this group athttp:// > groups.google.com/group/geoengineering?hl=en. > > > > -- > > > > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > > > > To post to this group, send email to geoengineering@googlegroups.com. > > > > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > > > > For more options, visit this group athttp:// > groups.google.com/group/geoengineering?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
