It seems to me that the value of CO2 and SRM can be interrelated via warming potential i.e. W/m2. If a doubling of air CO2 leads to a 3.7 W/m2 increase in forcing (IPCC), then doubling the current air CO2 load (400ppm x 7.76 GtCO2/ppm)= 3104 Gt CO2) to 6208 Gt CO2 means that for every Gt CO2 of the total of 3104 Gt added we increase the forcing by 0.0012 W/m2. Assuming that for every Gt of CO2 emitted only 45% stays in the atmosphere (in the near term) then the net forcing is 0.00054 W m^-2 per Gt CO2 emitted or 0.54 picoW m^-2 (tonne CO2 emissions avoided)^-1. If the social value of avoiding CO2 emissions is $30/tonne (Uncle Sam) and that cost only takes into account climate effects (not ocean acidification) then the value of either CO2 avoidance or SRM is $56 per pW/m2 avoided - no? Then in the case of SRM the issue becomes required timeframe of the avoidance - 100 years?
Greg -------------------------------------------- On Fri, 8/21/15, Andrew Lockley <[email protected]> wrote: Subject: Re: [geo] Tricky question - SRM / carbon credits To: "David Grober-Morrow" <[email protected]> Cc: "geoengineering" <[email protected]>, "Maggie Zhou" <[email protected]> Date: Friday, August 21, 2015, 1:31 PM David (and others) You're right that my question was inspired by the recent research showing that SRM gives a free CDR kicker. But this isn't the only way you could get carbon credits, as the temperature equivalence is a valid effect. The question is simply one of whether there will be any buyers. That will only be discovered when people start trying to sell the first SRM carbon credits. Bearing in mind you can get carbon credits from forestry schemes, my guess is that current credits aren't bought or sold on the basis of longevity. Having an SRM credit that's calibrated against an avoided ton CO2 over 100 years seems reasonable, and one that's equivalent over 1000 years would seem essentially irreproachable (based on RF). If people think this is illogical, illegitimate, immoral or illegal, then campaign for a ban. Don't shoot the messenger. Thanks Andrew On 21 Aug 2015 14:39, "David Morrow" <[email protected]> wrote: Andrew, I take it that you're thinking about the recent research showing that SRM could actually reduce the amount of CO2 in the atmosphere by reducing the amount of carbon released from (or not absorbed by) terrestrial sinks. (At least, I think that's the mechanism people find in the simulations -- if not, someone please correct me!). I agree with Olivier that there's no straightforward answer to the question about how much carbon a "unit" of SRM removes/keeps out of the atmosphere, both for the reason Olivier cited and because I take it the magnitude of the carbon reduction depends on background conditions (e.g., atmospheric concentrations and temperatures), which would evolve over time -- especially at the time scales needed to say that SRM has actually prevented carbon release, rather than delaying it. I also agree with Maggie that this isn't just a physics/earth science question. A carbon credit is a social creation. SRM isn't worth any carbon credits unless the relevant decision-making bodies say it is. And I think it would be a very bad idea for them to say so. So, in short, I'd say the answer to your question is: Currently, SRM is not worth any carbon credits; and it should stay that way, regardless of SRM's effects on atmospheric carbon concentrations. David On Thursday, August 20, 2015 at 7:47:40 PM UTC-4, Maggie Zhou wrote:Hi Andrew, Firstly, there is no sound answer to the question posed in terms of physics /earth science, exactly because SRM is not a true substitute of removing carbon, it does not confer the same effect in terms of duration of effect, and effect on many other aspects of the earth system other than the reduction of heat while the aerosol is in the air. So it is scientifically flawed to ignore all of that, in order to render a carbon credit equivalent so as to be able to monitize SRM, just like everything else is driven to be monitized under the insane capitalist system. Secondly, in a non-voluntary system that requires carbon credits in order to emit GHGs, SRM generated credits will simply add to the annual emissions cap, which is what I pointed out in my last email. In a voluntary system where people/corporations simply purchase carbon credits to feel better or use as a PR tool, SRM generated credits allow them to justify their emissions which they otherwise would be under greater pressure to reduce, and for those emissions outside of their direct control, SRM generated credits won't help reduce anyway. In fact they would feel even less responsible to change agricultural emissions (advocating for better agri practices, etc), or what their government is doing in their name. It's amusing, if not also sad, that you considered what I discussed in the last email as from a "political angle", i.e., not "science proper". I'd suggest that what I discussed there is simply science as applied to the physical reality of this earth, not some abstract concept that draws an artificial equivalence of SRM = C removal. Peace. Maggie Zhou, PhDhttps://www.facebook.com/maggie.zhou.543 On Thursday, August 20, 2015 7:00 PM, Andrew Lockley <[email protected]> wrote: Maggie (and list), Thanks for your response. However, there are a couple of problems with the stance you take. Firstly, I'm simply looking to answer a physics / earth science question. The answer will be true whether we want it to be, or not. The world deals with many other distasteful comparisons, such as how much is a life worth in cost-benefit analyses. Secondly, even if we engage with the political angle you discuss, your logic doesn't necessarily bear scrutiny. People may choose to offset only the components of their emissions they have no control over, eg agriculture, government sector, etc. I'd suggest that those buying carbon credits are probably more prone to taking mitigation action than demographically matched controls. I'd welcome further dialogue. Thanks Andrew Lockley On 20 Aug 2015 23:49, "Maggie Zhou" <[email protected]> wrote: "How many carbon credits is a tonne of SRM worth?" Seriously? This is precisely what geoengineering proponents promised that it won't be used for - as a substitute in any way, shape or form to carbon emission mitigation. To get acceptance for the idea of even funding research into SRM or other geoengineering schemes in response to global warming, the repeated promise was that it is not meant to replace emission reductions, only a backup to buy us some time... Using SRM to generate carbon credits is EXACTLY to generate EXTRA carbon emissions allowances - even though all SRM could do, at best, is masking the true impact of the current GHG levels on warming while the spraying is ongoing, without ever removing a single atom of carbon from the atmosphere for which it's to claim carbon credit. In short, SRM will lead to even MORE emissions, not less, and due to the masking and the lack of public awareness that it's the masking that's keeping the temperatures from shooting up even higher even quicker, it just helps keeping business-as-usual longer, on top of ocean acidification, acid rain, potential disruption of regional climate patterns, etc etc. Maggie Zhou, PhDhttps://www.facebook.com/maggie.zhou.543 On Thursday, August 20, 2015 4:15 AM, Andrew Lockley <[email protected]> wrote: How many carbon credits is a tonne of SRM worth? We could work this out as watts cooling or weight sulphur for weight carbon. Doesn't really matter. Thanks Andrew -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. 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