Dear Michael, I agree. If we can demonstrate to a sufficient certainty that a measure is sensible and cost effective, then lack of entire certainty is not a reason for inaction - decision theory deals well with these types of things, and often climate deniers have used a lack of absolute certainty as reason for inaction, which I dispute. I think it only sensible to abide by the certainty bounds provided by the physics in the models from scientific literature (such as the ones below), and have neither an stance that is pro or anti geoengineering. It could be useful to include the authors in on the discussion, although I don't think they would disagree with the quote you gave below.
Best wishes, Simon ________________________________________________ Simon Driscoll Atmospheric, Oceanic and Planetary Physics Department of Physics University of Oxford Office: +44 (0) 1865 272930 Mobile: +44 (0) 7935314940 http://www2.physics.ox.ac.uk/contacts/people/driscoll ________________________________ From: [email protected] [[email protected]] on behalf of Michael Hayes [[email protected]] Sent: 02 August 2013 19:59 To: [email protected] Subject: [geo] Re: Geoengineering carries unknown consequences I believe that Article 15<http://www.gdrc.org/u-gov/precaution-7.html> of the Rio Declaration provides the clearest thinking on this subject. "In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.". Best, Michael On Thursday, August 1, 2013 11:06:19 AM UTC-7, Simon Driscoll wrote: The physicists out there may have already seen this short article: http://www.physicstoday.org/resource/1/phtoad/v66/i8/p8_s3 (also copied down below) which may be of interest to group members. Best wishes, Simon +++ I read with interest David Kramer’s piece on geoengineering (Physics Today, February 2013, page 17<http://dx.doi.org/10.1063/PT.3.1878>). I must say, I am more alarmed by what the geoengineers in his report are proposing than by the climate changes that are taking place. I believe geoengineers are removed from scientific reality. They ignore the fact that the climate system and its components—clouds, hurricanes, and so forth—are highly nonlinear and thus very sensitive to the initial conditions and to changes in the parameters. Nevertheless, one could study the system’s response in a probabilistic way when certain parameters are changed or when we introduce fluctuations, if the relationships among all the components are known exactly. And here lies the whole problem with geoengineering. The formulation of the climate system and its components is only approximately known. More than 30 climate models are floating around in the climate community, and their predictions about general dynamics simply don’t agree with each other. In a recent publication,1<http://www.physicstoday.org/resource/1/phtoad/v66/i8/p8_s3#c1> we considered 98 control and forced climate simulations from 23 climate models and examined their similarity in four different fields (upper-level flow, sea-level pressure, surface air temperature, and precipitation). We found that except for the upper-level flow, the agreement between the models is not good. Moreover, none of the models compares well with actual observations. One person in the Physics Today story said that geoengineering may result in changes in various weather patterns, but nobody knows what the changes are going to be and how they will affect the climate system. If the warming in the Arctic is a big event to mitigate, then it will require a significant “geoengineering” effort. To me, that means significant changes will occur elsewhere. Who can say whether those changes will be less serious than those taking place now? How can geoengineers talk about modifying clouds and albedo when clouds are represented in the climate models as mostly linear parameterizations? Kramer’s report did not mention hurricanes, but geoengineers also propose to dissipate them. Hurricanes are unique in the climate system because they represent major self-organization. As physicists well know, self-organization occurs in dissipative systems in which energy is not conserved but instead is exchanged with the environment. Hurricanes involve huge amounts of energy. Scientists have little idea how the atmosphere and the ocean will be affected if that energy is not allowed to be exchanged. I would not have a problem with geoengineering if the physics and dynamics of the climate system were well known. Climate scientists have a good idea of the large-scale flow of ocean currents, but detailed measurements are not available. They know the basic physics of cloud formation and its thermodynamics but do not fully understand detailed cloud microphysics or the complex connections between climate and ecosystems. And with complex nonlinear systems, details are important. So we need to make an effort to improve our understanding of our climate system and its components before we try to operate on it. We can engineer a car or a plane because we know the underlying physics of motion, combustion, and flight, and we understand the role of every component. Can geoengineers say the same about climate? ________________________________________________ Simon Driscoll Atmospheric, Oceanic and Planetary Physics Department of Physics University of Oxford Office: +44 (0) 1865 272930 Mobile: +44 (0) 7935314940 http://www2.physics.ox.ac.uk/contacts/people/driscoll -- 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. -- 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]. 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