"bill" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > > > > > Among them, cloud feedbacks, > > > > > > http://www.grida.no/climate/ipcc_tar/wg1/271.htm > > > The potential complexity of the response of clouds to climate change > > > was identified in the SAR as a major source of uncertainty for climate > > > models. Although there has been clear progress in the physical content > > > of the models, ****clouds remain a dominant source of uncertainty*****, > > > because of the large variety of interactive processes which contribute > > > to cloud formation or cloud-radiation interaction: dynamical forcing > > > - large-scale or sub-grid scale, microphysical processes controlling > > > the growth and phase of the various hydrometeors, complex geometry with > > > possible overlapping of cloud layers. Most of these processes are > > > sub-grid scale, and need to be parametrized in climate models.
> > Source of uncertainty, yes. But this merely disproves your assertion that > > clouds are ignored in models. It also does not support your contention that > > clouds as a whole are a negative feedback. > > Is included incorrectly really an improvement on not included? bill, the point is that you are making very broad and damning claims and then when you are pressed for your reasons your claims shift. I am quite sure that no one here would disagree with you if you merely expressed the view that clouds are poorly represented in GCM's. Nor does expressing that as "models are stupid because.." provide anything constructive. It is in fact such a non-controversial point to bring up that you would be much better off to directly express your underlying reason for bringing it up. > Clouds at our current temperature range are not a predominantly > negative feedback, however, at higher temperatures, the increased > albedo causes a strongly negative feedback. > One of the things that REALLY bothers me about the gcms is that > even if they were fully described for the current conditions, as the > temperature rises, this might as well be a different planet, the carbon > cycle will change, the weather patterns will change, and next to > nothing is known about the nature of the changes. I can agree with this. But I submit that the models are good enough for policy decisions if they reliably tell us that the climate will change so much that they can not tell us exactly how these changes will manifest themselves. > > > > surface level albedo changes, > > > http://www.grida.no/climate/ipcc_tar/wg1/291.htm > > > At present, only limited global data sets for LSPs are available and > > > these need to be further improved. A comprehensive land-use/land cover > > > data set, providing a global time-series of vegetation and soil > > > parameters over the last two centuries at GCM resolution, would be a > > > very useful tool to separate land-use change impacts on regional > > > climate from global scale warming effects. Additionally, for both > > > historical analyses and future projections, there is a need for > > > interactive vegetation models that can simulate changes in vegetation > > > parameters and carbon cycle variables in response to climate change. > > > These proposed fourth generation models are just beginning to be > > > designed and implemented within climate models. > > Shortcomings and room for improvement, yes. But this merely disproves your > > assertion that surface level albedo changes are ignored in models. Where is > > your evidence that surface level albedo changes are a negative feedback? > > "limited datasets" is your idea of inclusion? again, including it > wrong isn't really much of an improvement in my view. And if you'd > read the link, you'd have seen that the researchers were predicting > predominantly negative effects from albedo changes. Additionally, > increased ocean area produces significantly higher albedos. The problem with this style of discourse is that it ultimately goes nowhere. Every counter point presented just results in a topic change and no one really learns anything. I won't bother pursuing any of these forks until we can get past accepting that these factors are in fact considered and concerted efforts are being made to better understand them, notwithstanding how poorly or not current understanding is. > > > > solar variations, > > > http://www.grida.no/climate/ipcc_tar/wg1/244.htm > > > > long term cycles of all stripes, > > > http://www.grida.no/climate/ipcc_tar/wg1/025.htm#e3 > > > As can be seen, there is a wide range of global scale internal > > > variability in these models. > > Again, nothing here to support your claims. > > The wide range of model results indicates that these are not > understood and that which isn't understood cannot be included. you'd > see it if you'd clicked the link. > > > > > methane release due to melting permafrost, > > > 4.5.3 Feedbacks through Natural Emissions > > > Natural emissions of N2O and CH4 are currently the dominant > > > contributors to their respective atmospheric burdens, with terrestrial > > > emissions greatest in the tropics. Emissions of both of these gases are > > > clearly driven by changes in physical climate as seen in the ice-core > > > record (Figure 4.1e). Soil N2O emissions are sensitive to temperature > > > and soil moisture and changes in rates of carbon and nitrogen cycling > > > (Prinn et al., 1999). Similarly, methane emissions from wetlands are > > > sensitive to the extent of inundation, temperature rise, and changes in > > > rates of carbon and nitrogen cycling. Natural emissions of the > > > pollutants NOx, CO, and VOC play an important role in production of > > > tropospheric O3 and the abundance of OH; and these emissions are > > > subject to similar forcings by both the physical and chemical climates. > > > Terrestrial and aquatic ecosystems in turn respond to near-surface > > > pollution (O3, NO2, acidic gases and aerosols) and to inadvertent > > > fertilisation through deposition of reactive nitrogen (often emitted > > > from the biosphere as NO or NH3). This response can take the form of > > > die back, reduced growth, or changed species composition competition > > > that may alter trace gas surface exchange and ecosystem health and > > > function. The coupling of this feedback system - between build-up of > > > greenhouse gases, human-induced climate change, ecosystem responses, > > > trace gas exchange at the surface, and back to atmospheric composition > > > -*****has not been evaluated in this assessment*****. The variety and > > > complexity of these feedbacks relating to ecosystems, beyond simple > > > increases with rising temperatures and changing precipitation, argues > > > strongly for the full interactive coupling of biogeochemical models of > > > trace gas emissions with chemistry and climate models. > > > > This is true, and I have a similar desire to see these things treated more > > thouroughly. But as you acknowledge this can only make things worse, and > > potentially much worse. > > yes. > > > > > and the > > > > absolutely stupid ghg value that is used for long term methane (it has > > > > an atmospheric half life of 1-2 years, after which it decomposes into > > > > CO2 and water, the stupidity is that in most climate modeling, they > > > > pretend that the water stays in the atmosphere, as though it were > > > > separate water not subject to rain) > > > I am sure that methane has a 500 year gwp of 6 if you keep all the > > > reaction products in the same test tube, however, in the atmosphere, it > > > has a 500 year (and in fact a 50 year) gwp of 1. > > And this relates to your claim that models don't account for rain how? > > My claim wasn't that the models don't account for the evaporation > cycle, it was that they don't account for it's effect on the GWP of > methane. Adding atmospheric water doesn't produce any noticeable > greenhouse effect, so pretending that the water formed by the > decomposition of methane fails to rain out and including it in the long > term GWP of methane is simply stupid. I do not believe you that any of the IPCC models make this mistake. You should either provide some model documentation that supports this or withdraw the claim. > Here's a list of mammals that lived quite well in the eocene (the > last time the temperature of earth was 22 degrees C for extended > periods. > http://en.wikipedia.org/wiki/Category:Eocene_mammals > > You seem to be laboring under the misaprehension that I am one of > the deniers or something. If anything, I am somewhere between alarmist > and fatalist. Do statements like "it's going to take everything we've > got to deal with the effects" and "we're going back to cretatious > conditions" and "start building refugee cities" really sound like an > AGW denier to you? No. But your penchant for very confident assertions of clear falsehoods is nonetheless frustrating. Coby --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. 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/globalchange -~----------~----~----~----~------~----~------~--~---
