Hi all, I'm restricting this analysis to geoengineering with stratospheric aerosols to save the Arctic sea ice. I've not received any additions to the list of pros and cons I posted on 29th April.
Some points have been discussed, mostly on 29th April also: S11. Cannot stop quickly William Fulkerson said that the stratospheric aerosol technique is effectively "reversible". I discussed this point, suggesting the technique might be employed in spring, such that most aerosol would be gone by the following winter. G2. Making a hash of things Stephen Salter argued that we don't often make a complete hash of things - it's just that hashes are more newsworthy than successes. Good research is a safeguard. G1-G11 General objections to geoengineering Eugene Gordon suggested small-scale experiments would not fall foul of any of these general objections. However, Alan Robock pointed out the difficulty of carrying out such experiments to get measurable results, without going full-scale. Alvia Gaskill begged to differ, and there was a discussion of layers in the stratosphere. I wrote to Prof Hansen asking for NASA help for experimentation (but no reply received). S10 If stop deployment, global warming will spring back Jim Thomas is worried by the effect of stopping deployment, leading to rapid warming. John Gorman said that the temperature would only rise to what you would have had without the geoengineering - there would be no overshoot and no lasting effect. (I don't think it would even rise that much. It would simply rise as fast as forced by the current CO2e level above pre-industrial, other things being equal. Of course the CO2e level may have gone up considerably while the geoengineering was being applied, so there will be a jump in the RATE of temperature increase, as you'd expect, but no inertial or coiled-spring effect. Is that right, Ken?) G3 The moral hazard This has been dismissed - as being the same argument used against adaptation! The Greenpeace position on this [1] was heavily criticised in the DIUS report [2]. I suggest that the moral hazard has to be discounted in balancing the risks, as it is impossible to quantify. Likewise all the other general fears in G1-11. For the time being I suggest we ignore the concerns of people who benefit from a warmer Arctic: CI-C3. Thus we should concentrate on B1-B7 and S1-S21. The benefits can be costed in terms of what happens if the sea ice disappears. Against this are the risks of undesirable effects of the geoengineering - the downsides. For obtaining a balance of risks, we need to: * calculate probability of success to halt Arctic warming and sea ice retreat; * estimate each benefit - as a cost of NOT doing the geoengineering (e.g. losing an ecosystem); * for each of these costs, multiply by probability of it happening if the sea ice disappears; * sum the above risks to be averted; * multiply by the probability of success to obtain overall benefit; * calculate probability of each downside; * estimate the cost of each downside; * multiply probability and cost to obtain risk from doing the geoengineering; * sum the downside risks to obtain total downside risk; * compare the overall benefit with the total downside risk. Is that a fair approach? As a refinement, we can vary the risk of geoengineering according to when we start deployment - which will vary according to when the Arctic sea ice first disappears. So we add the time dimension. Cheers, John [1] See David Santillo answer to Q39: http://www.publications.parliament.uk/pa/cm200708/cmselect/cmdius/uc1064-i/uc106402.htm [2] DIUS report - geoengineering section: http://www.publications.parliament.uk/pa/cm200708/cmselect/cmdius/uc1064-i/uc106402.htm ----- Original Message ----- From: John Nissen To: geoengineering Cc: [email protected] Sent: Wednesday, April 29, 2009 3:34 PM Subject: Balancing the pros and cons of geoengineering 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: [email protected] 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. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
