Alan It's true that the hardware does not exist, but it is misleading to say that "the technology does not exist" because most people will interpret this as meaning that something cannot be done using standard commercial engineering practices.
Since we are talking aerospace, compare two examples: * A new high-performance fire-fighting aircraft that could deliver 50 tons of water per pass. * A hypersonic passenger aircraft with ram jet propulsion. Neither exists today. If you put together specs for the water bomber you could get multiple bids with performance guaranties from the big aircraft companies, and if someone (U.S. Forest service?) paid the bill you could reasonably expect that the aircraft be delivered and work more or less as expected. Whereas, for the hypersonic passenger aircraft you could get companies to bid on engineering studies and test units, but not on a completed aircraft because no one knows how to do it, through the basic science is known. I suspect most people would say that the technology "exists today" in the former case and not in the latter. My recollection is that you have agreed with this clarification in previous discussions of this topic. Have you changed your mind? Now, turning to geo. Some of the technology does exist in the sense that you could procure the hardware in a few years. This is true of the modified business jet's in the Aurora report but it's not true of other systems we looked at like the sky-hose or the airships. Your comments about sulfur compounds ignore very large differences between the chemicals. H2S is toxic at a few hundred ppm. The idea of using large quantities of it in an aircraft or in balloons (as proposed in your paper) seems to me highly implausible. The risks to operators and the public would be very large. That's why we ignored that option in our paper. H2SO4 is routinely handled in industry today, it's one of the most common industrial chemicals. We proposed transporting S to the stratosphere (low mass and very easy to manage) and converting to SO3 in situ. We talked to a leading firm that engineers H2SO4 plants about designing a conversion system suitable for an aircraft and concluded that it was plausible using current technology. My view is that technology needed to begin putting sulfates in the stratosphere does exist today in the sense I have defined here. Of course some more speculative technology does not exist, but so what? Here is what I say in "A case for engineering the climate" (forthcoming from MIT press and available for pre-order at Amazon now<http://www.amazon.com/Climate-Engineering-Boston-Review-Books/dp/0262019825/ref=sr_1_1?ie=UTF8&qid=1378816897&sr=8-1&keywords=a+case+for+engineering+the+climate>, please excuse the self-promotion). One could in principle use existing aircraft such as jet fighters, but modern business jets are more efficient and much cheaper. A stock Gulfstream G650, a top-of-the-line business jet, cruises at altitudes up to 50,000 feet. If a G650 were retrofitted with a low-bypass military engine such as the Pratt & Whitney F100, it could lift a payload of 13 tons to 60,000 feet, an altitude that would likely be adequate for the minimal deployment. A fleet of just twenty aircraft acquired within a few years at a cost of $1.5 billion should enable sufficient radiative forcing to produce large-scale climatic effects that were just barely detectable[i]. The requisite deployment technology does not exist as ready-to-go hardware today, but it could be supplied by any number of vendors using what the aerospace industry calls commercial off-the-shelf technology. We could build the deployment hardware far more quickly than we likely could develop the rest of the science, engineering, and governance required to begin deployment of geoengineering. In this sense that one can say that the technology exists today. This is not an argument for or against immediate deployment. It is simply a statement of capability. Do you stand behind the statements you made in the article? Yours, David From: [email protected] [mailto:[email protected]] On Behalf Of Alan Robock Sent: Sunday, September 8, 2013 10:20 PM To: Ken Caldeira Cc: geoengineering Subject: [geo] Re: Washington Post story quoting Robock: "No technology exists to do solar radiation management" Dear Ken, Yes. The Aurora study and ours were both theoretical studies about the cost of taking sulfur to the stratosphere. But the technology does not exist. There are no planes with sulfur tanks and sprayers. There are no hoses and balloons. There is no artillery. If you wanted to start stratospheric geoengineering tomorrow you could not do it. In theory, such technology could be constructed, but the procedures for dealing with very dangerous sulfur compounds, SO2 or H2S or sulfuric acid have not been developed. Nozzles to spray the chemicals and try to produce aerosols of the desired size have not been developed. There is no supply chain for the different sulfur compounds you might want to use ready to be loaded onto planes. And there is certainly no squadron of planes waiting to do this. That is what I meant. By the way, there actually were a few errors in the story. The Pinatubo cloud lasted about 2 years, not 2 months. And I disagree with Lynn's characterization of CO2 emission as geoengineering. Geoengineering requires intent to control climate. Our study was: Robock, Alan, Allison B. Marquardt, Ben Kravitz, and Georgiy Stenchikov, 2009: The benefits, risks, and costs of stratospheric geoengineering. Geophys. Res. Lett., 36, L19703, doi:10.1029/2009GL039209. http://climate.envsci.rutgers.edu/pdf/2009GL039209.pdf Alan Alan Robock, Distinguished Professor Editor, Reviews of Geophysics Director, Meteorology Undergraduate Program Department of Environmental Sciences Phone: +1-848-932-5751 Rutgers University Fax: +1-732-932-8644 14 College Farm Road E-mail: [email protected]<mailto:[email protected]> New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock http://twitter.com/AlanRobock Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54 On 9/8/2013 10:57 PM, Ken Caldeira wrote: Jeff Bezos's rag has a story about "geoengineering": Alan, were you quoted correctly here? Did you really say "No technology exists to do solar radiation management"? If so, how do you square this position with the results of the Aurora report (http://www.keith.seas.harvard.edu/Misc/AuroraGeoReport.pdf) Justin McClellan, David W Keith, Jay Apt. (2012). Cost analysis of stratospheric albedo modification delivery systems. Environmental Research Letters, doi:10.1088/1748-9326/7/3/034019. (PDF<http://www.keith.seas.harvard.edu/papers/159.McClellan.2012.CostAnalysisOfStratosp.e.pdf>) http://iopscience.iop.org/1748-9326/7/3/034019 Note that the abstract of this paper states "We evaluate existing aircraft cost of acquisition and operations, ... " This does not sound like "No technology exists ..." http://www.washingtonpost.com/national/health-science/scientists-studying-solar-radiation-management-as-a-way-to-cool-planet/2013/09/08/cfb9def8-170c-11e3-be6e-dc6ae8a5b3a8_story.html Scientists studying solar radiation management as a way to cool planet [http://www.washingtonpost.com/rf/image_404h/2010-2019/WashingtonPost/2013/09/08/Health-Environment-Science/Images/77328837.jpg] Arlan N.Aeg/AFP/Getty Images - This picture, taken June 12, 1991, shows a giant mushroom cloud of steam and ash exploding out of the Mount Pinatubo volcano during its eruption as seen from inside a former U.S. air base in the Philippines. By Lenny Bernstein<http://www.washingtonpost.com/lenny-bernstein/2011/02/24/ABHUJyI_page.html>, Updated: Sunday, September 8, 7:25 PM E-mail the writer<mailto:[email protected]?subject=Reader%20feedback%20for%20%27Scientists%20studying%20solar%20radiation%20management%20as%20a%20way%20to%20cool%20planet%27> The 1991 eruption of Mount Pinatubo<http://pubs.usgs.gov/fs/1997/fs113-97/>, a volcano in the Philippines, blasted enough fine particles and sulfur dioxide gas into the atmosphere to envelop the Earth in a high-altitude cloud for the better part of two months. When scientists checked in 1992, they determined that the cloud had deflected enough sunlight to cool the planet by about 1 degree. Now, with the planet warming inexorably and the threat of long-term climate change looming, some experts are wondering whether the time may one day come when humans want to deliberately attempt such "solar radiation management." The idea is being investigated by, among others, the National Academy of Sciences, which is conducting research funded by the CIA, NASA and the National Oceanic and Atmospheric Administration. The academy has invited experts to discuss the idea Tuesday. But even considering such an endeavor raises many practical, economical, political and ethical questions, experts said, including what the effects on global and regional climates would be. "I'm not in favor of doing it today. I'm agnostic about whether we should ever do it," said Alan Robock, a distinguished professor of environmental sciences at Rutgers University. "We don't have enough information and, in any case, we don't have the technology." But Robock said additional research should be conducted despite concerns that determining the feasibility of such "geoengineering" might encourage a government or wealthy individual to try it, and could lessen efforts to curb greenhouse gases such as carbon dioxide. "I don't think you can just ignore it and pretend it doesn't exist, and sometime in the future, when someone becomes scared and wants to do it, they don't even know whether they can do it," he said. Mount Pinatubo's eruption sent an estimated 20 million tons of sulfur dioxide and ash <http://earthobservatory.nasa.gov/Features/Volcano/> into the stratosphere, where the sulfur dioxide formed sulfate particles that reflected sunlight back into space. Some believe this could be done effectively and at relatively low cost by injecting an aerosol of sulfur dioxide or some other gas into the atmosphere over a period of time, either from aircraft or powerful missiles. Ken Caldeira, a senior investigator for the Carnegie Institution for Science, told a congressional committee in 2009 that such methods are inexpensive, can be deployed quickly, and probably would cool the Earth effectively. He stressed, however, that it is more important to address the root cause of global warming by reducing the production of greenhouse gases. Carnegie will host a panel discussion on the subject Tuesday evening. But Robock, in an interview, said the effort is "not feasible. No technology exists to do solar radiation management. There are no airplanes, or hoses or missiles that exist to get sulfur up into the stratosphere." A more limited variation of the idea is to spray sea salt into clouds over the ocean, probably from ships, to form more water droplets in the clouds and make them whiter, said Lynn Russell, a professor of atmospheric chemistry at the Scripps Institute of Oceanography, which is part of the University of California at San Diego. The brighter clouds would reflect more sunlight. _______________ Ken Caldeira Carnegie Institution for Science Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected]<mailto:[email protected]> http://dge.stanford.edu/labs/caldeiralab @kencaldeira -- 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]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out. ________________________________ [i]. These estimates are based on a consulting study by an aerospace consulting company with experience developing high-altitude aircraft (see McClellan et al. cited in endnote 5). Twenty Gulfstream C-37A's allows about 0.45 million tons per year to the stratosphere. Assuming sulfur payload with conversion to SO3 in flight and using the results of Pierce et al. (cited in endnote 26) this gives about 0.4 Wm-2. -- 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. For more options, visit https://groups.google.com/groups/opt_out.
