Dear Mike, Yes, I agree we have barely scratched the surface for the number of strat/particle scenarios we need to test.
Sincerely, Oliver Wingenter On Jan 13, 7:38 pm, Mike MacCracken <[email protected]> wrote: > Dear Andrew and Tom-- > > While the preindustrial temperature might be right for preserving/restoring > Greenland and sea level, society has likely adapted to the conditions of the > past several decades, so going back to the 19th century would likely lead to > quite dramatic impacts to agriculture, killing frosts in many areas now > being farmed, etc. I would think the world decision would thus likely be at > a level somewhere between value in 1950 and about 1990. In any case, the > transition to such a temperature range should likely be sort of gradual and > not sudden--rapid changes cause increased impacts. > > I would also suggest that we no one has yet done any tests on having more > aerosols in one season than another. The average will likely be what > controls ocean temperatures, but land temperatures can be significantly > affected, so maybe focus on limiting summer warming and keep winters a bit > warm. From the orbital element results, to build up glaciers and ice sheets, > what we want is cool summers and warm winters (so there is more > snowfall)--of course, there is a lot of checking to do about how the > monsoons would be affected, etc. > > There is also the issue of latitudinal distributions. There are far more > than the two choices that have been simulated, namely global and Arctic > only. > > So, I would hold off on the idea of a single temperature change or goal--if > we are going to take control of the climate through geoengineering, we can > be subtle in our efforts, correcting the worst aspect of the changes, if not > all. Thus, I'd tend to agree that ultimately, there is going to have to be > some quite extensive consideration of what might be done. > > Best, Mike MacCracken > > On 1/13/09 9:17 PM, "Andrew Lockley" <[email protected]> wrote: > > > > > Bearing in mind that we're still unsure as to the various feedback > > effects, shouldn't the default position be that we should plan to go > > back to pre-industrial temperatures. Anything that we can later show > > is not needed is then a 'free gift' in terms of effort we don't need > > to expend. The alternative could be that we suddenly have to ramp up > > our efforts at the last minute when we realise that we've forgotten > > some deadly feedback. That seems like a bad way of planning. > > > A > > > 2009/1/14 <[email protected]>: > > >> Dear all, > > >> This is a non issue as it is already covered by Article 2 of the > >> UNFCCC. The global-mean temperature at which we should seek to > >> stabilize, vide Article 2, is one that avoids "dangerous anthropogenic > >> interference with the climate system" (etc., etc.) Whether we > >> stabilize the climate through mitigation (Kyoto Protocol), geoengineering, > >> or combined mitigation/geoengineering, the issue is the same. > > >> It is true that "dangerous interference" is not well defined, but > >> there is a large literature on this. > > >> The main difference between stabilization via mitigation or via > >> geoengineering is one of timescale. With mitigation there are two main > >> timescales, that associated with the carbon cycle and the slow response > >> of concentrations to emissions changes, and that associated with the > >> thermal inertia of the oceans. With geoengineering, the first timescale > >> is virtually eliminated (which might be seen as an advantage - see below). > >> The second timescale is common to all climate stabilization methods. > > >> Furthermore, there are two major sources of uncertainty in both cases. > >> In mitigation, there is uncertainty in relating emissions changes > >> to radiative forcing, and uncertainty in relating forcing to equilibrium > >> response (associated with climate sensitivity uncertainties). With > >> geoengineering, there is uncertainty in relating injection rate of > >> sulfur into the stratosphere to forcing, and the same climate sensitivity > >> uncertainty. The parallels are clear and obvious. > > >> Eliminating the first response time with geoengineering is, at first > >> blush. a big advantage. (Of course, we could do something similar with > >> mitigation, at least partly, by, e.g., reducing CH4 levels -- where the > >> timescale for concentration response is much less than for CO2, but we > >> cannot solve the problem with CH4 alone.) > > >> This response time issue has been addressed in the mitigation case in > >> the paper noted below. Here, we consider the issue of changing course, > >> in, e.g., the case where we decide on a stabilization level (say 550 > >> ppm) and then realize that we need a much lower level (e.g. 350 ppm). > >> With mitigation this is a tough call, because of inertia in the carbon > >> cycle. With geoengineering we would have a much better chance of saving > >> the planet from doom should we suddenly realize that the proposed > >> stabilization target was too high. Geoengineering might give us control > >> that we can never get with mitigation. > > >> Please excuse my ramblings here. My main point is that the issue of > >> what temperature to dial simply does not have to be considered any more > >> than it is or has been already. It is already covered by Article 2. > >> Perhaps not well covered -- but this is not a new problem. > > >> Tom. > > >> +++++++++++++++++++++++++++++++ > > >> Wigley, T.M.L., Richels, R. and Edmonds, J.A., 2007: Overshoot pathways > >> to CO2 stabilization in a multi-gas context. (In) Human Induced Climate > >> Change: An Interdisciplinary Assessment (eds. Michael Schlesinger, Haroon > >> Kheshgi, Joel Smith, Francisco de la Chesnaye, John M. Reilly, Tom Wilson > >> and Charles Kolstad), Cambridge University Press, 8492. > > >> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > >>> Dear Group, > > >>> The question of what temperature to "dial" in the Earth could also an > >>> important topic this proposed group could discuss and possibly decide > >>> on. > > >>> Oliver Wingenter > > >>> On Jan 12, 6:24 pm, "Andrew Lockley" <[email protected]> wrote: > >>>> No Oliver, I do think what's needed is an international Board of great > >>>> scientists and engineers. Whilst this body develops, I see an interim > >>>> Board composed of members of this group as a useful stepping stone. > >>>> However, you should note that I've already asked people to think of > >>>> non-googlegroup members who can contribute in order to 'raise the > >>>> game'. I certainly never thought for a moment that it should be > >>>> 'closed' to non-googlegroup people! > > >>>> Some of the initial members drawn from this googlegroup would probably > >>>> remain on this Board as it developed into a high-level panel, as this > >>>> googlegroup currently includes World-class scientists. Others > >>>> members, such as myself, would probably step down as the Board took on > >>>> other members. > > >>>> A > > >>>> 2009/1/13 Oliver Wingenter <[email protected]>: > > >>>>> Dear Andrew, > > >>>>> I think our plans are for different types of panels or boards. > >>>>> Correct me if I am wrong but yours would be comprised exclusively of > >>>>> Google geo members for the purpose of ranking project with yourself > >>>>> included so as to aid casual wiki users. Some projects are still in > >>>>> their infancy. > > >>>>> My notion is for an international panel comprised of scientist from > >>>>> many disciplines that can approve or endorse geoengineering projects > >>>>> nearly ready for deployment. Oversight is needed to avert possible > >>>>> eco disasters. > > >>>>> We may first want have an international committee whose sole purpose > >>>>> is to seat a permanent committee. > > >>>>> I am not proposing to take the lead. Some of Ken's stature is > >>>>> required. > > >>>>> Sincerely, > > >>>>> Oliver Wingenter > > >>>>> On Jan 12, 4:32 pm, "Andrew Lockley" <[email protected]> wrote: > >>>>>> (I endorse John's comments.) > > >>>>>> We won't all agree, but we do need to move forward together with > >>>> broad > >>>>>> consensus. At the moment we seem to have about a 50% split between > >>>>>> supporters and opposers. > > >>>>>> The way I see it we now have 4 choices for progressing the Board, and > >>>>>> the discipline as a whole. > > >>>>>> 1) We do nothing, relying on the 'current process' (whatever that is) > >>>>>> to deliver any necessary geoeng in time. I personally don't believe > >>>>>> there's currently enough scrutiny and oversight to encourage > >>>>>> politicians to take prompt action. > >>>>>> 2) The volunteers set up the Board in defiance of those people who > >>>>>> oppose such a move. This strikes me as divisive. > >>>>>> 3) The opposers could come up with a list of changes or rules they'd > >>>>>> need to see before they can support the board. This seems sensible, > >>>>>> if people are willing to do this. > >>>>>> 4) Someone can come up with a better idea, which we all do instead. > >>>> I > >>>>>> am sure there are some good ideas out there. > > >>>>>> Whilst I accept that not everyone will agree with whatever we decide > >>>>>> to do, I would like to think that people can at least be positive and > >>>>>> help the group make a decision that is supported by most people. I'd > >>>>>> also like to see people being respectful of everyone's opinion and of > >>>>>> the offer the volunteers have so kindly made. > > >>>>>> A > > >>>>>> 2009/1/12 John Nissen <[email protected]>: > > >>>>>>> Hi all, > > >>>>>>> I see a lot of negative comment to Andrew's suggestion. > > >>>>>>> But supposing somebody finds strong evidence that the Arctic sea > >>>> ice is very > >>>>>>> likely to disappear (at end summer) in two or three years, where > >>>> does he > >>>>>>> go? Don't we need a body of people who can say - well - there are > >>>> these > >>>>>>> particular geoengineering techniques that have a good chance of > >>>> helping to > >>>>>>> save the Arctic sea ice? As Ken said, there is no alternative to > >>>>>>> geoengineering for > > ... > > read more » --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
