Dear Andrew, I think it is the increase of salinity of the Gulf Stream and cooling as the waters proceed north that drives the Thermohaline circulation or ocean conveyor belt. For this we need not to much fresh water.
Sincerely, Oliver Wingenter On Jan 13, 8:10 pm, "Andrew Lockley" <[email protected]> wrote: > My worry with the suggestion of going back to the 'recent past' is > that it ignores many of the slow-acting effects and feedback systems > that may be crucial. I think the only viable approach is > precautionary - go back to 'Year Zero' > > I note your comments regarding cool summers and warm winters, but that > would surely have a terrible effect on agriculture, with all the > cooling falling in the growing season, and few frosts to kill winter > pests. > > Furthermore, it is the rapid buildup of ice in the Arctic that drives > the Thermohaline circulation. For this we need cold Arctic winters. > > If a layman like me can come up with several arguments against > 'fiddling with the dial', I guess the experts can come up with more. > > A > > 2009/1/14 Mike MacCracken <[email protected]>: > > > 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 > > ... > > 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 -~----------~----~----~----~------~----~------~--~---
