Hello John, The probabilistic risk assessment sounds like a good idea but from the wiki entry on the subject it seems to be limited to a single metric, I guess future global warming potential is a reasonable choice in this case. I may have misinterpreted this but with a single metric surely you would miss important things outside of your target such as regional precipitation changes. Could you clarify this part?
cheers, Pete On Feb 21, 2:50 pm, John Nissen <[email protected]> wrote: > Hello Peter, > To answer your question on cost/benefit, we need to analyse the balance of > the risks of geoengineering to cool the Arctic against the risks of not > geoengineering. This balancing of risks needs to take into account the > timescale of processes in the Arctic which give rise to the risks of not > geoengineering. For example, if these processes were very unlikely to build > up significant positive climate forcing or sea level rise over the next few > decades, one could be relaxed about geoengineering. But there is data about > the Arctic sea ice retreat, shown in a single graph, that gives much cause > for concern. The graph has been reproduced in the Copenhagen diagnosis > report [1]. > The graph is derived from one in this 2007 paper [2], by Stroeve, Serreze et > al, with additions for 2007 and 2008. Note that this paper was submitted > before the abrupt retreat of sea ice to achieve a record low September 2007. > In the light of such developments in the Arctic, and revised timing > estimates, we should prepare a risk analysis, but it will be in a separate > thread. > Note that, in terms of probabilistic risk assessment (PRA) [3], we have risk > defined thus:In a PRA, risk is characterized by two quantities:the magnitude > (severity) of the possible adverse consequence(s), andthe likelihood > (probability) of occurrence of each consequence. > Conventional cost-benefit analysis [4] is not quite what we are looking for, > because it assumes the status quo is acceptable:Cost–benefit analysis is > typically used by governments to evaluate the desirability of a given > intervention. It is heavily used in today's government. It is an analysis of > the cost effectiveness of different alternatives in order to see whether the > benefits outweigh the costs. The aim is to gauge the efficiency of the > interventionrelative to the status quo. The costs and benefits of the impacts > of an intervention are evaluated in terms of the public's willingness to pay > for them (benefits) or willingness to pay to avoid them (costs). > However we can try to "gauge the efficiency of the intervention"relative to > no interventionin our analysis. We also need to take probabilities and > timescale into account, in order to compare immediate intervention with > delayed intervention. Of course, the "costs" of intervention must include > the risks of adverse consequences. > Cheers from Chiswick, > John > [1] See fig 13 page > 30:http://www.ccrc.unsw.edu.au/Copenhagen/Copenhagen_Diagnosis_LOW.pdf > [2] Published in Geophysical Research Letters and reproduced > here:http://www.smithpa.demon.co.uk/GRL%20Arctic%20Ice.pdf > [3]http://en.wikipedia.org/wiki/Probabilistic_risk_assessment > [4]http://en.wikipedia.org/wiki/Cost-benefit_analysis > --- > p.j.irvine wrote:dear Gregory Benford, It seems that there is an assumption > that cooling the arctic is essential and trumps any potential impacts in > other parts of the world. I'm not sure how it would be achieved but I believe > that an in-depth cost-benefit assesment of any proposed geoengineering scheme > is essential. For example, If the suspected impact of an arctic intervention > was a cooling of the arctic but also a change in hydrology in another part of > the world; surely to justify the intervention it would have to be proved that > the overall effect was positive? I can imagine their are a lot of tricky > things to quantify, the impacts of runaway climate change for tundra melt, > the subjective value of any predicted change in the climate, etc. (and a lot > of unquantifiable things besides) but I believe the principle should remain. > Do you agree that this principle of a calculated or expected positive global > impact should be satisfied before any geoengineering intervention s > undertaken? The alternative seems to justify regions or countries modifying > regional climate for their benefit regardless of detrimental impacts > elsewhere. regards, Pete Irvine On Feb 20, 4:44 pm,[email protected]:All: > Stephen, this transfer function is for tropospheric spraying, yes? The strato > cases are not nearly so predictable. I'd expect the tropo sprays don't > propagate far, anyway. National legislation to protect geo experiments from > lawsuits is crucial. As David says, international treaties will help, but I'd > estimate they will take far longer, and delay is our enemy. I'd be happy with > the Arctic Council defending their experiments, as they have clout and > standing. Gregory Benford -----Original Message----- From: David > Schnare<[email protected]>Cc: > geoengineering<[email protected]>Sent: Sat, Feb 20, 2010 7:56 > am Subject: Re: [geo] SRM geoengineering: how to deal with the losers? Pete: > My sense is that who will be a winner or loser is an unknowable unknown. > While I agree with Professor Salter that we could take a stab at it, and > indeed others on this list have made some preliminary attempts to look at > precipitation issues, the sad reality is that models are dreadfully > inadequate for regional analyses and greater computing power will not be > enough to make them much more useful. In the absence of quality > information, humankind has used a best guess, iterative approach, achieved > through international treaty. My suspicion is that will be what will have to > happen here to address winners and losers. I am concerned, however, that > such an approach will not work if potential "losers" demand stipulated > reparations. Schnare On Sat, Feb 20, 2010 at 9:38 AM, p.j.irvine > <[email protected]> wrote: It is likely that any SRM > geoengineering intervention will create winners and losers and some nations > may always be against any intervention whatsoever. Gregory Benford raised the > issue of reaching agreement on the global scale and how problematic it would > be. If for example the arctic council of nations agreed to initiate a > decade-long field trial to cool the arctic by 1 C, how could they deal with > complaints from nations who felt that this experiment had induced a negative > change in their climate? In any given year there are floods, droughts, > heatwaves, etc. but during this field trial a fraction of these events would > be attributed (rightly or wrongly, partially or fully) to the intervention. > Two questions arise: Could it be determined if any changes in the climate > (outside of the target area) had occurred as a result of the intervention > during a 10 year trial? How would aggrieved nations or peoples seek > reparations for perceived negative impacts (scientifically proven or > otherwise)? best regards, Pete Irvine PhD student School of Geographical > Sciences University of Bristol -- You received this message because you are > subscribed to the Google Groups "geoengineering" group. To post to this > group, send email [email protected]. To unsubscribe from this > group, send email [email protected]. For more > options, visit this group > athttp://groups.google.com/group/geoengineering?hl=en. -- David W. Schnare > Center for Environmental Stewardship -- You received this message because you > are subscribed to the Google Groups "geoengineering" group. To post to this > group, send email [email protected]. To unsubscribe from this > group, send email [email protected]. For more > options, visit this group > athttp://groups.google.com/group/geoengineering?hl=en. -- 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.
