Hi Stephen,
Did you or Ben conduct a signal to noise analysis for this? (Sorry, I haven't read his thesis, nor walked through quantitative analysis myself.) When we did our testing paper a few years back, we found that a global-scale forcing of 1 W/m^2 would still take decades to get adequate signal to noise ratio on precipitation effects on an area the size of India, for example. If you forced 2% of the surface area with 50 W/m^2, the time taken I'd think would be of the same order. Maybe this isn't a big problem in a model one can run for centuries, and if the result is robust across multiple models, one might have some confidence in it. But harder still (that is, need more information) if you want to also identify how things depend on the month of forcing, for example. There's no magic inherent in a pseudo-random signal, simply the ability to generate many uncorrelated sequences so you can test multiple locations with the same model run (if the frequency response was flat, you could do the same by using a different forcing frequency at each location, for example). Testing paper is here: MacMynowski, D. G., Keith, D., Caldeira, K., and Shin, H.-J., "Can we test geoengineering? <http://pubs.rsc.org/en/Content/ArticleLanding/2011/EE/c1ee01256h> " Energy and Environmental Science, 4(12), pp 5044-5052, 2011. doug -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stephen Salter Sent: Monday, June 03, 2013 11:06 AM To: [email protected] Subject: Re: [geo] Re: Marine Cloud Brightening pros & cons. Alan Robock criteria Dear Alan I was pleased to hear that you will be looking at marine cloud brightening and look forward to seeing your results. I attach a note on an idea which might be able to get an everywhere-to-everywhere transfer function of all the effects. The first results from Ben Parkes show the intriguing result that spray from the Aleutian islands can reverse the drying effects in the Amazon caused by spray off Namibia. Can you offer any suggestions about causes of cross-hemisphere influence ? I hope that modellers will be able to use the idea and vary spray time and place in the light of the phase of monsoons and el Nino. Stephen On 03/06/2013 17:09, Alan Robock wrote: > Dear John, > > We are designing an MCB GeoMIP experiment so we can see how robust the > results are from the climate models that have already done these > experiments, but all differently. In theory, there would be both > benefits and risks, and these must be quantified. From my list, you > can cross our ozone depletion, no more blue skies and effects on > remote sensing and astronomy, as well as other stratosphere-specific > issues. But I think it is premature to claims that MCB would be safe > and effective. And detailed indoor computer modeling experiments will > be needed to provide an environmental impact statement for outdoor > experiments. Indeed, a lot more research is needed. > > Alan > > Alan Robock, Distinguished Professor > Editor, Reviews of Geophysics > Director, Meteorology Undergraduate Program > Associate Director, Center for Environmental Prediction > Department of Environmental Sciences Phone: +1-848-932-5751 > Rutgers University Fax: +1-732-932-8644 > 14 College Farm Road E-mail: <mailto:[email protected]> [email protected] > New Brunswick, NJ 08901-8551 USA <http://envsci.rutgers.edu/~robock> http://envsci.rutgers.edu/~robock > <http://twitter.com/AlanRobock> http://twitter.com/AlanRobock > > On 6/3/13 4:56 AM, John Latham wrote: >> To-: [[email protected]];[[email protected]] >> From:- [[email protected]] >> >> Hello Alan & Colleagues, >> >> Yes, as & when convenient it would be interesting, Alan, to learn >> from you which of your 26 objections to stratospheric seeding apply >> to Marine Cloud Brightening (MCB): and, of course whether there are >> additional ones pertaining to MCB, which do not apply to the sulphur >> idea. >> Consideration of MCB has not been evident in the recent plethora of >> blog submissions, so I would like to provide a list of its associated >> positive and negative qualities which - in my view, on balance - >> provide a convincing case for being one of the SRM techniques to be >> selected for research support. >> >> 1.Computations from several top-class models agree in concluding that >> MCB - if it works - could maintain the Earth's average surface >> temperature and the sea-ice coverage at both poles at roughly the >> current values, at least up to the CO2-doubling point. >> >> 2.Development of a system for spraying adequate quantities of >> sea-water aerosol is not yet fully achieved, but recent developments >> indicate a high likelihood of success. >> >> 3.Ship-tracks provide hard evidence of the capacity of aerosol to >> brighten clouds, but it does not follow that it can be achieved on >> the spatial scale required. >> >> 4. GCM computations indicate in one case that MCB deployment would >> produce unacceptable rainfall reduction in Amazonia, whereas in two >> other studies that is not so. Further work shows that the Amazonian >> rainfall loss can be eliminated by not seeding in a particular >> region. Provisionally, it seems possible that adverse rainfall >> effects can be avoided by judicious choice of seeding locations. >> >> 5.We have designed a three-phase field-test of MCB, based heavily on >> the larger, highly successful International VOCALS study, in which >> several members of our team played leading roles. Its scale would be >> about 100 km by 100 km, which seems too small to influence climate. >> Such a test would not be conducted without appropriate authorization. >> Please see reference below. >> >> 6. In principle, MCB is capable of being usefully applied on spatial >> scales much less than global. A paper on the utilization of MCB to >> weaken hurricanes was published in 2012 (see below). Another, on the >> protection of coral reefs has just been accepted. In both cases the >> idea is to reduce ocean surface water temperatures in appropriate >> oceanic areas. >> >> Best Wishes, John. >> >> 10. John Latham, Keith Bower, Tom Choularton, Hugh Coe, Paul >> Connolly, Gary Cooper,Tim Craft, Jack Foster, Alan Gadian, Lee >> Galbraith, Hector Iacovides, David Johnston, Brian Launder, Brian >> Leslie, John Meyer, Armand Neukermans, Bob Ormond, Ben Parkes, >> Philip Rasch, John Rush, Stephen Salter, Tom Stevenson, Hailong Wang, >> Qin Wang & Rob Wood, 2012, Marine Cloud Brightening, Phil.Trans.Roy. >> Soc. A . 2012, 370, 4217-4262. doi: 10.1098/rsta.2012.0086 >> >> 12.John Latham, Ben Parkes, Alan Gadian,Stephen Salter, 2012. >> Weakening of Hurricanes via Marine Cloud Brightening (MCB), >> Atmospheric Science Letters, DOI: 10.1002/asl.402 >> >> >> >> >> >> >> >> John Latham >> Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 >> Email: <mailto:[email protected]> [email protected] or <mailto:[email protected]> [email protected] >> Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 >> or (US-Cell) 303-882-0724 or (UK) 01928-730-002 >> <http://www.mmm.ucar.edu/people/latham> http://www.mmm.ucar.edu/people/latham >> ________________________________________ >> From: <mailto:[email protected]> [email protected] >> [[email protected]] on behalf of Alan Robock >> [[email protected]] >> Sent: 01 June 2013 18:03 >> To: <mailto:[email protected]> [email protected] >> Subject: Re: [geo] NASA Ames meeting >> >> Dear Stephen, >> >> My list of 26 problems is in slide 157 of >> <http://climate.envsci.rutgers.edu/RobockGeoEngineering72ForDistribution.ppt > http://climate.envsci.rutgers.edu/RobockGeoEngineering72ForDistribution.ppt >> >> I have been mainly focused on stratospheric aerosols. My latest >> publication on this is a response to Seitz's bubbles proposal at >> <http://climate.envsci.rutgers.edu/pdf/Bubble2.pdf> http://climate.envsci.rutgers.edu/pdf/Bubble2.pdf Some of the issues >> also apply to marine cloud brightening (MCB). >> >> Our GeoMIP project is making progress on understanding the climate >> response to stratospheric aerosols. We are beginning additional >> experiments related to MCB, and they will be described in a paper that >> will be submitted later this month to a special issue on GeoMIP to be >> published in JGR. I'll send it out as soon as it is submitted. >> >> Alan >> >> Alan Robock, Distinguished Professor >> Editor, Reviews of Geophysics >> Director, Meteorology Undergraduate Program >> Associate Director, Center for Environmental Prediction >> Department of Environmental Sciences Phone: +1-848-932-5751 >> Rutgers University Fax: +1-732-932-8644 >> 14 College Farm Road E-mail: <mailto:[email protected]> [email protected] >> New Brunswick, NJ 08901-8551 USA <http://envsci.rutgers.edu/~robock> http://envsci.rutgers.edu/~robock >> <http://twitter.com/AlanRobock> http://twitter.com/AlanRobock >> >> On 6/1/13 9:52 AM, Stephen Salter wrote: >>> Dear Alan >>> >>> Can you tell me which of your 26 objections apply to marine cloud >>> brightening? >>> >>> I am sure that many of the people who want research on but not >>> deployment of geoengineering systems are greatly reassured that you >>> are there to spot the nasty problems. Keep up your valuable work. >>> >>> I too was at the Ames meeting and confirm your recollection. >>> >>> Stephen >>> >>> Emeritus Professor of Engineering Design School of Engineering >>> University of Edinburgh Mayfield Road Edinburgh EH9 3JL Scotland >>> <mailto:[email protected]> [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 >>> <http://WWW.see.ed.ac.uk/~shs> WWW.see.ed.ac.uk/~shs >>> >>> >>> >>> On 01/06/2013 17:33, Alan Robock wrote: >>>> Dear All, >>>> >>>> I also was at the NASA Ames meeting. It was my first geoengineering >>>> meeting, and it was there that I was struck with the very >>>> enthusiastic endorsement of geoengineering as a solution to global >>>> warming by people who did not seem to be aware of the potential >>>> negative impacts. But Lane and Kheshgi were not among those who were >>>> blindly advocating geoengineering, as I remember it. I agree with >>>> Clive that the reason we are even considering this Plan B is that >>>> Exxon and other fossil fuel companies have had a dedicated campaign >>>> to deny anthropogenic global warming, and that AEI has been part of >>>> this campaign, and that if they were to now advocate mitigation we >>>> would not be nearly as interested in geoengineering. But it was not >>>> such a black and white discussion at the Ames meeting - it was more >>>> of a general discussion of geoengineering and a learning opportunity >>>> for many. >>>> >>>> It was at the Ames meeting that I wrote down my 20 reasons why >>>> geoengineering may be a bad idea, as I listened to two days of >>>> presentations. (My research program since then has been to >>>> investigate those reasons. I have now crossed out three of them, but >>>> added nine new ones, so the total is now 26.) >>>> >>>> Alan >>>> >>> >> -- >> 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 <mailto:[email protected]> [email protected]. >> To post to this group, send email to <mailto:[email protected]> [email protected]. >> Visit this group at <http://groups.google.com/group/geoengineering?hl=en> http://groups.google.com/group/geoengineering?hl=en. >> For more options, visit <https://groups.google.com/groups/opt_out> https://groups.google.com/groups/opt_out. >> >> > -- Emeritus Professor of Engineering Design School of Engineering University of Edinburgh Mayfield Road Edinburgh EH9 3JL Scotland <mailto:[email protected]> [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 <http://WWW.see.ed.ac.uk/~shs> WWW.see.ed.ac.uk/~shs The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. -- 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 <mailto:[email protected]> [email protected]. To post to this group, send email to <mailto:[email protected]> [email protected]. Visit this group at <http://groups.google.com/group/geoengineering?hl=en> http://groups.google.com/group/geoengineering?hl=en. For more options, visit <https://groups.google.com/groups/opt_out> https://groups.google.com/groups/opt_out. -- 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?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
