If I was being considered for some responsible position where my views were to count for something, I would probably blurt out: believing that man-made CO2 is the main determinant of global temperature, or all of global climate, is not simply believing that the tail wags the dog; it is believing that a flea on the tail wags the dog. Then I would be widely laughed at, and disqualified.
Harper and Obama are more sensible. Do nothing to speak of to implement Kyoto, much less launch into a new round of madness with Copenhagen, but mouth a few pieties about intending to combat climate change when the time is right--that is, when the major contributors of CO2 come to the table. It does no good to the environment, and can do harm to our own economy, to act on our own.
Meanwhile, lots of media stories for a study claiming to show that there have been more record highs than record lows since 1950, indicating a clear warming trend. The authors apparently say: there should be a trend toward fewer and fewer records, high or low, since there should be a kind of normalcy in temperature. Really? Constancy is the norm in nature? Somehow the boomers all think that there was a kind of peace or changelessness when they were children, and that is the way it should be. The study puts its entire reliance on U.S. surface monitoring stations, and claims that some adjustment has been made to allow for problems with siting. This of course is Anthony Watts' specialty, so he will have something to say along with Roger Pielke. (The naive, surface-based record for the whole twentieth century shows a couple of decades of cooling alternating with a couple of decades of warming. No one has a model that can explain these changes--they certainly don't co-relate with a steady increase in man-made CO2).
The reports on this study make no mention of man-made causes of temperature change other than CO2, and certainly makes no mention of causes other than man-made for any large scale climate change. Is this realistic? Two other studies, both of which received far less media attention, accept that there has been a certain amount of temperature increase, but say that much of the increase is attributable to changes of land use--basically urbanization. One says half of the increase is owing to this one factor. So: this is human intervention, but not CO2 production per se. Simply living at higher density, with more asphalt,lights and other electrical and industrial equipment, a higher concentration of motor vehicles generating heat, etc.
So: assume temperature increase. Half from urbanization and other changes of land use. The other half--probably not entirely man-made. Maybe very little of it man-made?
Meanwhile, the ocean, along with "terrestrial ecosystems," turn out to be absorbing all the extra carbon we have thrown at them so far. It is hard to say what the upper limit of the earth's capacity for absorption is, or where the so-called "tipping point" is--if indeed there is one in the simple way that is often presented. If the carbon is 100% absorbed by the ocean and earth, I gather it may have nothing to do with any temperature changes or climate changes.