A couple of comments (also see http://www.climatesciencewatch.org/2007/05/12/maccracken-on-lindzen¹s-mislea ding-newsweek-op-ed/):
If the climate sensitivity is as low as Lindzen suggests, it becomes virtually impossible to explain how the Cretaceous could be about 6 C warmer than at present and how the peak glacial period could be 6 C colder than present. Basically, Lindzen argues that warming leads to less water vapor and cirrus in the upper troposphere, so with the Cretaceous, there must be none there at all, and for the glacial, it must be very wet there‹but then one cannot get the temperature change. Lindzen once responded in the past to this critique that the climate sensitivity is low for relatively smooth changes in forcings (i.e., GHGs) and much higher for forcings with strong horizontal gradients. If this is the case, then the sulfate aerosol forcing that is very regional should be causing a very large (presumably) cooling influence that would seem likely to overwhelm the warming influence of GHGs. But we don¹t see this. A critical issue for both the GHG and climate engineering analyses is whether the climate sensitivity really varies a lot or a little between forcings; where there do appear to be some differences is between forcings that affect the IR balance of the convectively coupled troposphere and those like black carbon that absorb solar radiation aloft . The analysis Lindzen did to come to his conclusion was, as I understand it, mainly to look at satellite data for vertical columns, especially out over the Pacific Ocean. What the analysis neglects are the effects of the region¹s circulation patterns, such as the monsoon. The analysis seems to basically assume that the cloud-radiation vertical profiles for a given surface temperature will be the profiles as the whole region warms and the locations of the particular temperatures with respect to land-ocean circulations change. It really seems implausible to me. As far as I know, neither he nor anyone else has been able (over the dozen or so years he has held this position) to put together a global model with a parameterization that gives the result he suggests. In my view, if reporters are going to write stories about his results, they need to be asking him much tougher questions about his claims and not let him get out of facing up to the tough questions. Opting to present one view versus another (even quoting more than one mainline scientist is not enough) is really a cop out. Mike MacCracken On 5/1/12 4:55 PM, "RAU greg" <[email protected]> wrote: > "Richard S. Lindzen, a professor of meteorology at the Massachusetts Institute > of Technology, is the leading proponent of the view that clouds will save the > day. His stature in the field ‹ he has been making seminal contributions to > climate science since the 1960s ‹ has amplified his influence. > > "Dr. Lindzen says the earth is not especially sensitive to greenhouse gases > because clouds will react to counter them, and he believes he has identified a > specific mechanism. On a warming planet, he says, less coverage by high clouds > in the tropics will allow more heat to escape to space, countering the > temperature increase." > > more here: > http://www.nytimes.com/2012/05/01/science/earth/clouds-effect-on-climate-chang > e-is-last-bastion-for-dissenters.html?emc=tnt&tntemail0=y > -- 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.
