Michael and Nathan – Many thanks for your thoughts on this! To answer your question Nathan; yes, we need to explore this further. We have a new satellite remote sensing tool that appears to show the right conditions for “cirrus stripping” during polar winter, but these results are preliminary. Conditions for this technique could be better in the polar winter stratosphere; stay tuned…
David Mitchell From: [email protected] [mailto:[email protected]] On Behalf Of nathan currier Sent: Wednesday, February 04, 2015 5:38 PM To: Michael Hayes Cc: Geoengineering FIPC; Oliver Morton; Andrew Revkin; John Latham; David Keith; [email protected]; Dr. Adrian Tuck; Ken Caldeira; Andrew Lockley; Michael MacCracken Subject: Re: [geo] Re: Washington Post op ed By the way, as a follow up to that, has anyone proposed using this very same material as the source of an Arctic geoengineering idea - that is, has anyone proposed something like "cirrus stripping" but for polar stratospheric clouds instead, as a way of helping to cool the Arctic? Might there be a feasible way of doing this? Cheers, Nathan On Wed, Feb 4, 2015 at 8:25 PM, nathan currier <[email protected]<mailto:[email protected]>> wrote: Hi, Michael & Adrian - Thanks so much for all of this, which I personally think is very important material. I found the Sloan-Pollard paper fascinating, in spite of, and maybe partly also because of, the fact that it isn't a new paper, yet seems to inject a fresh and tantalizingly relevant paleoclimate perspective into this discussion of the role of Arctic stratospheric clouds in Arctic climate - and thus by inference how Arctic stratospheric sulfur injection could get entangled in all of that in a pretty nasty way. Some months ago now, when Ken was asking about "bad memes of geoengineering", and I mentioned what I saw as the "Pinatubo meme" and the vague thoughts I had been having about stratospheric H2O, its role in warming, and various potential interconnections with both methane and sulfur, and thus more "hidden" positive forcings from it that went along with the often discussed and more obvious negative ones, I didn't imagine that what I was thinking of as the worst possible kinds of direct connections would be so likely as it seems from what you have just sent. Right off the bat, one thing it suggests to me is that Arctic-only sulfur SRM in the stratosphere, which I too had thought was a good idea when I first had heard of it, might turn out to have been one of the worst geoengineering ideas proposed, potentially causing more harm than good. Add to that that Adrian had written then about how the lofting will work quite poorly in the Arctic, as discussed in his paper. To be fair, it is still the net effect that matters, and when I first wrote about this to the group, I did my own little entirely unprofessional back-of-the- envelope calculation, in terms of global sulfur SRM issues and Pinatubo, using the Solomon et al paper on the contribution of stratospheric H2O to warming in the 90s, and hypothesized, based on some other papers describing how volcanic injection of H2O can play out in the stratosphere for ~5-10 years, a "what if" in which a large % of that 90s H2O perturbation had come directly from Pinatubo itself, how bad would that be for its overall forcing profile, and yet I found that even then (not so likely) it would it reduce the cooling efficacy by something like 50% I think it was, at most....and the amount of that positive forcing tied directly to the sulfur would be far smaller, too, since H2O is directly injected in the process............. But in the Arctic-only stratospheric sulfur SRM case, on the other hand, it sounds as though there might be the potential for the whole idea to actually be close to being outright pernicious and entirely useless!.....very interesting......thanks again..... Cheers, Nathan On Wed, Feb 4, 2015 at 5:52 PM, Michael Hayes <[email protected]<mailto:[email protected]>> wrote: Oliver and List, The primary cloud condensate nuclei for type one polar stratospheric clouds is sulfuric acid. This is a well known and established fact found in atmospheric physics. Here I offer a few reference among the many available: 1) Theoretical and Modeling Studies of the Atmospheric Chemistry of Sulfur: Hazem S. El-Zanan The relevance of the above book, to this topic, is found within the introduction. 2) A 2D microphysical model of the polar stratospheric CN layer<http://onlinelibrary.wiley.com/doi/10.1029/1999GL900187/abstract> 1. Michael J. Mills1, 2. Owen B. Toon1and 3. Susan Solomon2 "Each spring a layer of small particles forms between 20 and 30 km altitude in the polar regions. We present the first self-consistent explanation of the observed “CN layer” from a 2D microphysical model of sulfate aerosol. Our theory relies on photolysis of H2SO4 and SO3, consistent with recent laboratory measurements, to produce SO2 in the upper stratosphere and mesosphere. An additional source of SO2may be required. Nucleation throughout the polar winter extends the top of the aerosol layer to higher altitudes, despite strong downward transport of ambient air. This may affect heterogeneous chemistry at the top of the aerosol layer in polar winter and spring.". Please pay close attention to the 'Particle Microphysics' section and the conclusion in the above paper. Further, if we take a close look at the 'Pinatubo Effect', in relationship to ozone production with elevated SO2 levels, we find a significant downward trend in the "global mean column ozone". This scenario is explained in the following paper. Please see pg. 403, 2nd column, 4th-5th para.: 3) Atmospheric effects of the Mt. Pinatubo eruption<http://www.nuclear.lu.se/fileadmin/nuclear/Undervisning/Atmosfaerskurs/P04.pdf>: MP McCormick, LW Thomason, CR Trepte - Nature, 1995 However, we can find reference to the apparent contradictions found in the premise that SAI offers no threat to polar stability while lowering the 'global average temperature' in a far more topical references...such as: 4) Polar stratospheric cloud<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#Types> (Wiki) PSCs are classified into three types Ia, Ib and II according to their chemical composition<http://en.wikipedia.org/wiki/Chemical_composition> which can be measured using LIDAR<http://en.wikipedia.org/wiki/LIDAR>. The technique also determines the height and ambient temperature of the cloud.[4]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-wegener-4> · Type I clouds contain water, nitric acid<http://en.wikipedia.org/wiki/Nitric_acid> and/or sulfuric acid<http://en.wikipedia.org/wiki/Sulfuric_acid> and they are a source of polar ozone depletion<http://en.wikipedia.org/wiki/Ozone_depletion>.[5]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-5> · Type Ia clouds consist of large, aspherical particles, consisting of nitric acid trihydrate (NAT).[4]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-wegener-4> · Type Ib clouds contain small, spherical particles (non-depolarising), of a liquid supercooled<http://en.wikipedia.org/wiki/Supercooled> ternary solution (STS) of sulfuric acid, nitric acid and water.[4]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-wegener-4> · Type Ic clouds consist of metastable<http://en.wikipedia.org/wiki/Metastability> water-rich nitric acid in a solid phase.[6]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-6> · Type II clouds, which are very rarely observed in the Arctic, consist of water ice<http://en.wikipedia.org/wiki/Ice> only.[4]<http://en.wikipedia.org/wiki/Polar_stratospheric_cloud#cite_note-wegener-4> (My highlights) 5) Also, the Harvard website "Equable Climate Dynamics-Polar Stratospheric Clouds<http://www.seas.harvard.edu/climate/eli/research/equable/psc.html>" offers a well written oversight of PSC trapping polar heat and the reference section has a number of citations worth reading. 6) And again, we should pay close attention to the paper I originally sited for a view of the PSC dynamics within an ancient "greenhouse" world. Please pay close attention to the 'Discussion' section. Polar Stratospheric Clouds: A high latitude warning mechanism in an ancient greenhouse world: Sloan and Pollard <ftp://ftp.tudelft.nl/pub/TUDelft/irctr-rse/Mieke/Papers/SloanPollard98-PSCforHighLatPTMwarmArctic.pdf> In brief summation, an intentional increase in stratospheric sulfuric acid, per SAI, will trigger a corresponding increase in the most common PSC type of formation (type 1) and thus this action would represent an intentional increase in polar temperatures. Thus, such intentional actions would constitute a knowable action resulting in the intentional acceleration of polar methane hydrate releases and the existential threat that such releases pose (i.e. Arctic Methane Tipping Point<https://robertscribbler.wordpress.com/tag/esas/>). Thus, the intentional injection of sulfuric acid into the atmosphere represents an real and significant threat to climate stability, as we know it, and will further accelerate the current trend towards an equitable (unstable) climate....intentionally. Oliver, thank you for your question and I hope my response offers a reasonable degree of information for you to decide for yourself if SAI is or is not a threat to polar (and global) climate stability as opposed to the current hyperbolicly positive rhetoric concerning the efficaciousness of the SAI concept. Best regards, Michael On Wednesday, February 4, 2015 at 7:53:31 AM UTC-8, olivermorton wrote: What's the proposed SAI mechanism enhancing PSC? On 4 February 2015 at 01:48, Michael Hayes <[email protected]<mailto:[email protected]>> wrote: Hi Folks, This level of discussion on SAI seems to be premature. We have yet to see any...any...models concerning the highly predictable increase in Polar Stratospheric Cloud (PSC) production which will be caused by SAI. This is not a trivial precondition to further discussion. As, the triggering of an Arctic Methane Tipping Point, through increasing PSC production, would make SAI simply a dysfunctional option. Please read the following paper concerning the vital need to....not...increase PSCs through SAI. Polar Stratospheric Clouds: A high latitude warning mechanism in an ancient greenhouse world. <ftp://ftp.tudelft.nl/pub/TUDelft/irctr-rse/Mieke/Papers/SloanPollard98-PSCforHighLatPTMwarmArctic.pdf> Best, Michael On Friday, January 30, 2015 at 12:54:21 AM UTC-8, Andy Parker wrote: Hey folks, the Washington Post just published an op ed on the messy politics of solar geoengineering, written by David Keith and me: http://www.washingtonpost.com/opinions/whats-the-right-temperature-for-the-earth/2015/01/29/b2dda53a-7c05-11e4-84d4-7c896b90abdc_story.html -- You received this message because you are subscribed to a topic in the Google Groups "geoengineering" group. To unsubscribe from this topic, visit https://groups.google.com/d/topic/geoengineering/LJWQD4s2w_U/unsubscribe. To unsubscribe from this group and all its topics, send an email to [email protected]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. 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