on mon NUMBER NUMBER NUMBER at NUMBER NUMBER jim whitehead wrote you have not explained why the increase in coNUMBER concentrations is not contributing to increasing global temperature there are a number of reasons to think that coNUMBER is not important to controlling global temperature and that much of the coNUMBER increase may not be anthropogenic some recent research points worth mentioning recent high resolution studies of historical coNUMBER concentrations and temperatures over hundreds of thousands of years have shown a modest correlation between the two in a number of cases coNUMBER level increases are not in phase with temperature increases and actually trail the increase in temperature by a short time i e increases in temperature preceded increases in coNUMBER concentrations the more studies that are done of the geological record the more it seems that coNUMBER concentrations are correlated with temperature increases but are not significantly causative there is a lot of evidence that coNUMBER levels are regulated in a fairly stable fashion i don t believe anyone really has an authoritative answer as to exactly how this works yet with respect to absolute coNUMBER concentrations it is also important to point out that our best data to date suggests that they follow a fairly regular cycle with a period of about NUMBER NUMBER years at previous cycle peaks the concentrations were similar to what they are now if this cycle has any validity and we only have good data for NUMBER NUMBER complete cyclical periods but which look surprisingly regular in shape and time then we should be almost exactly at a peak right now as it happens current coNUMBER concentrations are within NUMBER of other previous cyclical concentration peaks for which we have good data in other words we may be adding to the coNUMBER levels but it looks a lot like we would be building a molehill on top of a mountain in the historical record at the very least there is nothing anomalous about current coNUMBER concentrations also coNUMBER levels interact with the biosphere in a manner that ultimately affects temperature again the interaction is not entirely predictable but this is believed to be one of the regulating negative feedback systems mentioned above last as greenhouse gases go coNUMBER isn t particularly potent although it makes up for it in volume in some cases gases such as water and methane have a far greater impact as greenhouse gases on a per molecule basis water vapor may actually be the key greenhouse gas something that coNUMBER only indirectly effects through its interaction with the biosphere coNUMBER was an easy mark for early environmentalism but all the recent studies and data i ve seen gives me the impression that it is largely a passenger on the climate ride rather than the driver i certainly don t think it is a healthy fixation if we re actually interested in understanding warming trends cheers james rogers jamesr URL 