Folks Part of this thread is spinning into an exercise in drafting a statement. I suggest that this activity move off-line to a smaller group.
A few specific comments: 1. “we have a method that does not use sulphur”. Maybe. As a method of SRM, sea salt aerosols offer many potential advantages and some serious disadvantages. For this reason I strongly support research including active field research. But, there are still **very** large uncertainties and it is entirely possible that the method will prove to have very limited applicability. Over hype of high-leverage technologies is a recipe for disaster. 2. Stratospheric sulfates are plausible because (a) we know how to deliver sulfate at low cost with current technologies and (b) the experience with volcanic emissions gives us some confidence that we understand some of the key chemistry and physics. There will still be unexpected outcomes. Here is a specific example. I you wanted to increase the radiative forcing using strat sulfate aerosols at a rate sufficient to roughly offset the growth of anthropogenic radiative forcing you would need ramp up the sulfate addition rate at about 1/3 of a Mt-S per decade. That is if you started at zero you would need about 1/3 of a Mt-S per year after a decade and 2/3 after two decades. (This assumes 0.25 Wm^-2/decade forcing ramp and 0.7 Wm^-2 for 1 Mt-S/year see; Pierce et al, http://www.keith.seas.harvard.edu/preprints/127.Pierce.EfficientFormStratsAerosol.p.pdf) Sulfate aerosols in the stratosphere are promising. I would not support deployment without a much broader effort on both science and governance, but with luck, I think this could be accomplished reasonably quickly. There are lots of other options that offer similar promise. We are spending considerable effort thinking about how to increase the effectiveness and understand the risks of sulfate and other aerosols. 3. Tropospheric sulfates require much large injection rates to achieve the same radiative forcing. Do the math on health impacts using paper I cited a few posts back. It’s not promising. I would respectfully suggest that one be cautious about propose something that will have health consequences that large without a **very** clear rational for why you are doing it. David From: Tenney Naumer [mailto:[email protected]] Sent: Wednesday, March 21, 2012 8:06 PM To: Mike MacCracken Cc: P. Wadhams; Nathan Currier; Geoengineering; Andrew Lockley; [email protected]; Govindasamy Bala; Veli Albert Kallio; David Keith; [email protected]; John Nissen; Peter R Carter; Gary Houser; Anthony Cook; Graham Innes; PaulHenry Beckwith; Brian Orr; JON HUGHES; Nick Breeze Subject: Re: Rough sketch of a small-scale tropospheric aerosol program Dear Mike, I think the point is that we have a method that does not use sulphur. The fact that many people are exposed to atmospheric sulphur now is no logical justification for its use in geoengineering. We need cleaner air in general. World governments need to invest in methods for drawing down CO2 and rid the air of other man-caused aerosols. Why exacerbate a problem that we will have to work extra hard to clean up later? Best regards, Tenney Tenney Naumer "Climate Change: The Next Generation<http://climatechangepsychology.blogspot.com>" Tel.: (618) 967-6453 (cell) skype: tenneynaumer On Wed, Mar 21, 2012 at 3:45 PM, Mike MacCracken <[email protected]<mailto:[email protected]>> wrote: Peter and Tenney-- I think your proposed proscription of sulfur is too harsh a restriction. As far as people are concerned, the problems have come with high concentrations and lots of other toxins mixed with them from fossil fuel power plants. As far as ecological impacts are concerned, aside from there being agricultural areas that are sulfur deficient and farmers add sulfur, the problems arise in certain types of situations (like accumulated deposition onto the snow fields of Scandinavia and then rapid melting; downwind of major industrialized areas; etc). In any case, as well, we will continue to have volcanic injections so sulfur won't be going away. On low sulfur fuel, that is mandated to happen over next several years, mainly because of problematic emissions and concentrations in port areas. This is likely, however, to have much larger scale implications as the diesel fuel is cleaned up. CCN approach and cloud whitening is great to try, but is mainly effective in clean areas where there is marine stratus and and a bit hard to do in other areas where that is not the case. Thinking that one is going to find an approach that has no side effects of any kind is, in my view, wishing for the impossible. It is, as I posed in an earlier email, like insisting on a cure for HIV/AIDS rather than accepting drugs that are able to hold off worsening of the disease while one searches for better approaches. Mike MacCracken On 3/21/12 1:59 PM, "P. Wadhams" <[email protected]<mailto:[email protected]>> wrote: > Yes, I agree. We have a very feasible technique in cloud whitening using > water vapour which I think should be researched flat out and then, if it's > feasible, put into action. It will not arouse opposition on the grounds of > adding yet another poison to the atmosphere, whereas sulphur will end up as > a absolute no-no for that same reason. Ditto I think we should keep quiet > about low-sulphur fuel. It would look extremely bad if we were seen to be > advocating a new form of pollution, Best wishes Peter > > or On Mar 21 2012, Tenney Naumer wrote: > >> I think we have to be extremely vigilant in *not* associating AMEG with any >> type of geoengineering that uses sulfur -- all the research that I know of >> since the idea was first broached leads one to the conclusion that it is >> not a good idea to put sulfur into the atmosphere. >> >> Tenney Naumer "Climate Change: The Next >> Generation<http://climatechangepsychology.blogspot.com> >> " >> Tel.: (618) 967-6453<tel:%28618%29%20967-6453> (cell) >> skype: tenneynaumer >> >> >> >> On Wed, Mar 21, 2012 at 7:25 AM, Mike MacCracken >> <[email protected]<mailto:[email protected]>>wrote: >> >>> Hi Nathan--Just a note that the sulfate layer is mainly based on what >>> happens above the boundary layer (so lifetime is of order a week) and >>> the NAAQS levels of SO2, etc. are at the surface, so not directly >>> comparable. Once surface SO2 emissions were reduced by switching away >>> from coal for home heating, etc. in the first third of the 20th century >>> or so (at least in the US), the thrust of air pollution control for SO2 >>> for the middle third of the century became to loft it so it blew away >>> from the source (unintentionally creating the sulfate loading), and only >>> later became focused on simply reducing SO2 emissions. So, one has to be >>> careful of the linkages you make. >>> >>> I certainly agree the calculations need to be made. >>> >>> Mike >>> >>> >>> On 3/20/12 10:30 PM, "Nathan Currier" >>> <[email protected]<mailto:[email protected]>> wrote: >>> >>>> Since none of those with the skills to do these calculations much more >>>> professionally seem to be jumping in quickly to take over the reigns, >>>> I'll try not to embarrass myself in giving initial crude answers to my >>>> own question from the other day, which follow: >>>> >>>> I find that in a recent paper from MIT (Leibensperger, 2011), the >>>> localized RF from sulfate aerosol¹s direct effect for the eastern US >>>> is estimated as -.3W/m2. Then, if we estimate for Twomey/Albrecht >>>> indirects, we can say roughly something like -.5W/m2 for the current >>>> eastern US sulfate forcing. >>>> >>>> What are the sulfur levels giving this RF? The basic NAAQS - annual >>>> average primary standard - is still unchanged from the 1970s. (http:// >>>> www.epa.gov/air/sulfurdioxide/<http://www.epa.gov/air/sulfurdioxide/>), at >>>> 30ppb (about 80 micrograms/m3). >>>> But in actuality, average regional levels now only range from 1-6ppb >>>> across the US. There was apparently talk lately of introducing a new 5- >>>> minute standard for asthmatics, but it was not done, and I think we >>>> can all agree that a geoengineering approach could be designed to >>>> avoid spikes pretty well, so the annual average of course, in our >>>> case, it would really be a three or four month average is alone what >>>> matters here. >>>> >>>> So, let¹s examine some actual current annual average local levels a >>>> bit. >>>> http://www.epa.gov/airtrends/sulfur.html >>>> >>>> I live now in New York City. The most complete reading here is from a >>>> midtown Manhattan monitor station, where as recently as 2003 SO2 seems >>>> to have been around 14ppb, but the data ends in 2007, by which time it >>>> had dropped to ~11ppb. I used to live rather close, it would seem, to >>>> that particular monitoring station back in the early 1990s, when the >>>> levels it read were closer to 20ppb, but let¹s take something nearer >>>> the lower figure and be conservative. Either way, this area entails >>>> some of the highest readings in the eastern US for SO2 pollution that >>>> I found. >>>> >>>> Look at the interactive map's levels around the rest of the eastern US >>>> - they are really surprisingly low now almost everywhere. I was >>>> shocked when I looked at it (no wonder warming is ahead of the models! >>>> At least it suggests the termination effect won¹t be too bad here in >>>> the US - we¹ve already gone through much of it!). Within that 1-6ppb >>>> range, let¹s say it¹s an average of 3ppb? >>>> >>>> Now, then, is it not accurate to say that we should be able to go up >>>> to 3x or even 4x that -.5W/m2 without making any air that is worse >>>> than Manhattan's has been very recently? That is, if we aimed for >>>> ~12ppb level. Is this really so bad, so evil? I didn¹t realize I was >>>> torturing myself by living here! I walk my dog almost daily in the one >>>> old growth section of the city (Inwood Hill Park), where there is >>>> plentiful lichen, moss, etc. Birds of all varieties seem healthy and >>>> in robust populations. A new species of leopard frog was just >>>> discovered here, as you might have read the other day. It is not >>>> pristine, but I found a crayfish walking around by a stream in Central >>>> Park. I have even had asthmatic friends who love living here, except >>>> in the heat of summer. >>>> >>>> Is this air I am breathing every day really so noxious and dangerous >>>> that you would not want to consider using it, in an almost completely >>>> unpopulated area moreover, even if thereby you could help stave off a >>>> potential arctic disaster? Really? >>>> >>>> Next, what are the levels of SO2 currently in Siberia? There is one >>>> former gulag site where there is today smelting and other industry >>>> that emits massive SO2, but that is far from the ESAS and otherwise >>>> the level seems to be very low. One recent paper I found (Lee et al, >>>> 2011), that aims to constrain SO2 global emission estimates by looking >>>> at ozone and other satellite data (OMI and SCIAMACHY), makes it appear >>>> in a map as though the area in question is extremely low, although it >>>> is not at all detailed. >>>> >>>> Thus, my supposition is that we could possibly get some 2W/m2, >>>> possibly half the local net forcing, without creating any air worse >>>> than New York City¹s has been just in this past decade. Please >>>> correct me if that seems to be mistaken. >>>> >>>> The current modeled estimates for ESAS talik extent suggest about 3-5% >>>> of total area. Thus, to give an adequate buffer around this, to >>>> effectively cool incoming waters, etc, covering 10% of ESAS area = >>>> ~50,000 sq. miles. Now, maybe some of those with better expertise can >>>> figure the dispersal rates, column depth, etc, etc and estimate how >>>> just how much sulfur this would entail, that is, to emit enough S to >>>> cover ~50,000 sq. miles with about 12ppb SO2 for about four months per >>>> year, how much sulfur is that? Thanks much in advance for your answer, >>>> I appreciate it. >>>> >>>> Lastly, in terms of the addition of methane effects, I find that it >>>> would at best add only about .1W/m2, and possibly almost nothing >>>> measurable. Using a very rough methane RF (including all indirect >>>> effects, i.e., from Shindell et al, 2009) of 1000ppb=~1W/m2, then with >>>> an anomaly there ranging from +100-200ppb, and a possible maximum 40% >>>> reduction emission rate from local wetlands if the anomaly were >>>> completely caused by wetland emissions, which I very strongly doubt >>>> then still at best one would only get -.1W/m2. So that factor would be >>>> very unlikely to be significant. Obviously, MCB could/should then be >>>> added to or combined with the above. Latham hasn¹t responded, so maybe >>>> someone else could give a rough estimate of what the options might be >>>> to use them together and what those effects might be? >>>> >>>> I am, I confess, somewhat frustrated by some of the experts here >>>> excepting Mike not in their expertise, which I always find >>>> impressive, but in their seeming inability, or perhaps unwillingness, >>>> to use such expertise more flexibly. John Nissen¹s exchange with >>>> Latham a few days ago, with John¹s poignant questions, I found almost >>>> painful to read, frankly (of course, I can appreciate that MCB deals >>>> with much the same complexities as CLAW, which after 800 papers is >>>> still mired in controversy but maybe that only connotes that another >>>> 5 years of modeling still won¹t alone resolve John's questions, but >>>> doing Lovelock¹s version of what some have branded ³improvisatory >>>> experimentation,² i.e., simply getting out into the field and making >>>> small prototypes and playing around variously with different >>>> parameters until you start to get what you are looking for, could be a >>>> better and quicker way to go?). >>>> >>>> As to the fundamental question of risk in dealing with tropospheric >>>> SO2, I think it¹s probably safe to say that there is likely zero >>>> global-scale risk whatsoever to the proposed plan. The risks of a >>>> large-scale excursion of methane, if one took place, on the other >>>> hand, are without question extraordinary. I think that¹s the kind of >>>> circumstance where you decide it¹s best to act with relatively >>>> imperfect knowledge. None of us know what the probability of a large >>>> CH4 emission really is. And none will ever know what "might have >>>> been", whether we act or don¹t act, had we taken the ³other path.² >>>> That's what decision is all about. Nor do I imagine that anyone can >>>> really say whether what I am proposing would actually be effective, >>>> but as I just suggested for John's designs, one could always alter the >>>> parameters easily in real time. >>>> >>>> I think that in a larger context of fighting climate change >>>> altogether, what I'm suggesting also represents one possible ³step 1² >>>> or ³2² towards the lowest-possible-risk pathway forward, which is what >>>> everyone should be striving for, it seems to me. That is, the >>>> combination of a very large and rapid non-CO2 (CH4/BC) emissions >>>> program (please keep in mind, members of AMEG, that the recent >>>> Shindell paper had the good news that, if Asia is less important for >>>> Arctic BC forcing than some thought, it also means that a rather small >>>> number of northern European and Scandinavian countries can be quite >>>> important in reducing that arctic BC forcing and therefore AMEG >>>> could and should ALSO be engaged in urgently requesting the UK >>>> government to be the spearhead for such a program, including more >>>> advanced diesel filters, etc) and at the same time, alongside it, >>>> some kind of small-scale, pinpointed geoengineering program like the >>>> one I am suggesting here, should, if done together, be able to push >>>> back strongly against the dissolution of the arctic as we know it for >>>> a while. Obviously that's hardly the end of the story, just steps 1 >>>> and 2, the first chapter. >>>> >>>> Then, along with steep declines in carbon emissions, the kind of SRM >>>> geoengineering that some here consider ³serious² (both Revkin and >>>> Keith used that word in recent days seemingly to distinguish what they >>>> have in mind from what I am proposing), best pegged exclusively to >>>> lost aerosol loading (thus, no setting of any global ³thermostat² as >>>> in Keith¹s conundrum), which would then itself be pegged in its >>>> termination to subsequent CDR, through biochar, reforestation and >>>> other technologies like Keith¹s artificial tress, etc. All that >>>> together creates, I think, the minimum-risk path ahead, five >>>> interlinked steps that might indeed have to be step-ordered. >>>> >>>> On what Fuller called a ŒCritical Path¹, if you don¹t follow the first >>>> steps first, you can forget about getting to the end of the process. >>>> If the patient stops breathing in the ambulance on the way to the >>>> emergency room for a quadruple bypass, you can kiss your elaborate >>>> surgery plans goodbye if you won¹t be able to get them breathing again >>>> first. A big methane excursion could be like that patient stopping >>>> breathing, essentially ending all hope of moving to a political >>>> solution on emissions, and the dangers of that seems to be growing >>>> considerably. Again, no significant risks in this "step 1" treatment I >>>> propose, obvious huge risks in sitting by and watching the thing that >>>> is feared. >>>> >>>> all best, >>>> >>>> Nathan >>>> >>> >>> >>> >> -- 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.
