This scare ,that stratospheric areosols would result in an even more global warming if stopped, has appeared in many articles. I therefore read the relevent papers fairly carefully and my reading is that temeratures would simply rise quickly to where they would have been without geoengineering. i.e. exactly what one would expect.
There is no overshoot and no lasting effect. These are of course the model simulations -I think one of them might have been Ken's- but I suspect that Mount Pinatubo would give the same conclusion . In articles this is often coupled with the suggestion that geoengineering has been done instead of emissions reduction but noone here is sugesting that. John Gorman ----- Original Message ----- From: "jim thomas" <jimthomas...@gmail.com> To: <wf...@utk.edu> Cc: <j...@cloudworld.co.uk>; "geoengineering" <geoengineering@googlegroups.com>; <brian.laun...@manchester.ac.uk> Sent: Wednesday, April 29, 2009 5:10 PM Subject: [geo] Re: Balancing the pros and cons of geoengineering Bill I don't see how you can consider SRM reversible. The modelling I've seen (eg paper by Matthews and Caldeira) suggests that halting aerosol injections will lead not just to a rapid jump in temperature but indeed a jump to a higher global temperature than if geo-engineering had not been attempted because of the weakening of carbon sinks. If stopping is that dangerous than politically speaking this is not a reversible technology. Once you've started it would be too dangerous to stop I'm talking here about aerosols specifically - I would be interested to hear from Ken, Alan and others whether they would expect the same dangerous jump in temperatures if a cloud whitening scheme were to 'switched off'. Jim Thomas ETC Group. On Wed, Apr 29, 2009 at 10:52 AM, William Fulkerson <wf...@utk.edu> wrote: > Dear John: > I did not see a principal advantage of SRM listed. That is that it is > reversible, at least for sulfates in the stratosphere and for cloud > whitening. > Cheers, > Bill > On Apr 29, 2009, at 10:34 AM, John Nissen wrote: > > > Hi all, > > Alan Robock has said: > > "Whether we should use geoengineering as a temporary measure to avoid the > most serious consequences of global warming requires a detailed evaluation > of the benefits, costs, and dangers of different options." > > As you may already know, I am keen for rapid development and deployment of > SRM (solar radiation management) in the Arctic, with some benefits (if > successful): > > B1. Save the Arctic sea ice and associated ecosystem. > B2. Slow (and preferably halt) Arctic warming. > B3. Reduce discharge of CO2 and methane, contributing to global warming > and > ocean acidification. > B4. Reduce risk of massive methane discharge, sufficient to add several > degrees of global warming. > B5. Slow the rise in sea level from Greenland glaciers. > B6. Reduce risk of Greenland ice sheet destabilisation, and associated 6 > metres of sea level rise. > B7. Develop the SRM techniques to use at other latitudes. > > B4 amounts to a reduction in the risk of such catastrophic global > warming that human civilisation could not survive. > > Against this we have the concerns of those who currently benefit from a > warmer Arctic: > > C1. Oil and mining industries, prospecting in the Arctic region. > C2. Traders who use the North-West passage. > C3. Greenlanders and others who may prefer a warmer climate (cf. Inuit, > who > are having their way of life destroyed). > > I think we should try to counter people's natural fears about SRM > geoengineering, especially stratospheric sulfur aerosols. What are the > most > frequent objections? One often reads that the remedy (geoengineering) may > be worse than the disease (global warming). We need to present a balanced > picture. > > General fears: > > G1. Geoengineering is interfering with nature. (I heard that fear only > this morning.) > G2. We've made such a hash of interventions in the past, we're bound to > make a hash of geoengineering. > G3. Moral hazard - geoengineering is a licence to continue CO2 pollution. > G4. Geoengineering is being offered as a silver bullet, which it cannot > be. > G5. You'll need international agreement - and that will be even more > difficult to get than agreement on emissions reduction. > G6. Too expensive - we always underestimate. > G7. Too cheap, so anybody could do it. > G8. It will not work. (We heard at the DIUS hearing "if emissions > reduction doesn't work, why should geoengineering work") > G9. It will work - but you might overdo it by mistake, leading to an ice > age. > G10. High risk of "unknown unknowns" turning out to be disastrous > side-effects. > G11. Our understanding is too limited. To quote the "Climate Safety > report": > > ".. even with the extraordinary advances in climate science to date, our > understanding of it has not developed to such a point as to allow > confidence > that deploying direct cooling techniques would not cause more harm than > good." [1] > > > Specific fears of stratospheric aerosols (from Robock [2]): > > S1. Could have adverse effect on some regional climate(s) and ecosystem(s) > [4] > S2. Doesn't help with ocean acidification. > S3. Ozone depletion. > S4. Effect on plants (but more diffuse light has positive benefit?) > S5. Acid rain (noting that Alan Robock has withdrawn this particular > objection) > S6. Effect on cirrus clouds. > S7. Disappearance of blue skies (and appearance of red sunsets?) could > have > negative psychological impact. > S8. Less sun for solar power. > S9. Environment impact of implementation (e.g. if put sulfur in jetliners > fuel). > S10. If stop, previously suppressed global warming will spring back to hit > you. > S11. Cannot stop quickly enough, if you did need to. > S12. Human error, with means of delivery, causing dreadful accident. > S13. Moral hazard = G3. > S14. Cost = G6 > S15. Commercial control of technology > S16. Military use of technology > S17. Conflict with current treaties > S18. Control of the thermostat > S19. Questions of moral authority > S20. Unexpected consequences = G10. > > Alan has since withdrawn objections on acid rain, S5, and cost, S14, but > added a new one [3]: > > S21. Ruin astronomical observations > > Do we have any more benefits, concerns, general fears or specific fears to > add to these lists? > > Cheers, > > John > > > [1] http://climatesafety.org/wp-content/uploads/climatesafety.pdf > > [2] http://www.thebulletin.org/files/064002006_0.pdf. Also see [3]. > > [3] Email from Alan Robock to the geoengineering and climate > intervention groups on 9th April: > > ---- > > Dear All, > > As some of you know, I published a paper last year: > > Robock, Alan, 2008: 20 reasons why geoengineering may be a bad idea. > Bull. Atomic Scientists, 64, No. 2, 14-18, 59, doi:10.2968/064002006. > > http://climate.envsci.rutgers.edu/pdf/20Reasons.pdf > > which also produced a roundtable discussion: > > http://www.thebulletin.org/web-edition/roundtables/has-the-time-come-geoengineering > > Since then, I have been evaluating these reasons and two of them seem to > not be of concern, excess acid deposition and cost. Our two papers on > these results, now under review, are: > > Kravitz, Ben, Alan Robock, Luke Oman, Georgiy Stenchikov, and Allison B. > Marquardt, 2009: Sulfuric acid deposition from stratospheric > geoengineering with sulfate aerosols. Submitted to J. Geophys. Res. > > http://climate.envsci.rutgers.edu/pdf/AcidDepositionJGRsubmitted.pdf > > Robock, Alan, Allison B. Marquardt, Ben Kravitz, and Georgiy Stenchikov, > 2009: The practicality of geoengineering. Submitted to Geophys. Res. > Lett. > > http://climate.envsci.rutgers.edu/pdf/practicality8NoFig3.pdf > > But I have also been giving talks on the subject and two days ago a > member of an audience suggested another reason why geoengineering (with > stratospheric aerosols) may be a bad idea: > > It would ruin Earth-based optical astronomy! > > With the tremendous investment in equipment, and mountain-top > observatories to get above most of the junk in the atmosphere, not to > mention sophisticated signal processing algorithms to remove the > remaining atmospheric influence, how could astronomers stay silent and > allow permanent clouds that would block their seeing? > > Alan > > Alan Robock, Professor II > Director, Meteorology Undergraduate Program > Associate Director, Center for Environmental Prediction > Department of Environmental Sciences Phone: +1-732-932-9800 x6222 > Rutgers University Fax: +1-732-932-8644 > 14 College Farm Road E-mail: rob...@envsci.rutgers.edu > New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock > > ---- > > [4] Robock et al. > > Regional Climate Responses to Geoengineering with Tropical and Arctic SO2 > Injections > > [quote] The safety and efficacy of the recent suggestion of injection of > sulfate aerosols into the Arctic stratosphere to prevent sea ice and > Greenland from melting while avoiding adverse effects on the biosphere at > lower latitudes [Lane et al., 2007] are not supported by our results. > While > Arctic temperature could be controlled, and sea ice melting could be > reversed, there would still be large consequences for the summer monsoons, > since the aerosols would not be confined to the polar region. > > > > Bill Fulkerson, Senior Fellow > Institute for a Secure and Sustainable Environment > University of Tennessee > 311 Conference Center Bldg. > Knoxville, TN 37996-4138 > wf...@utk.edu > 865-974-9221, -1838 FAX > Home > 865-988-8084; 865-680-0937 CELL > 2781 Wheat Road, Lenoir City, TN 37771 > > > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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