Where do you lose the plot?

Where indeed.

There is no such thing as global warming. it is a THERMODYNAMIC impossibility on this planet at this time in geological history. Human impacts on the environment can redistribute thermodynamic heat and create conditions for CLIMATE CHANGES, principally through wastewater dumping in coastal oceans (much more that in the atmosphere). Humans cannot change the trajectory of biospheric cooling and natural oscillations within that trajectory. See fig 1-6 in http://muller.lbl.gov/pages/IceAgeBook/history_of_climate.html
for details of this trajectory over the past 3 million years.

Solving COMPLEX biospheric systems without due regard to TOTAL energy inventories is typical of specialist scientists who are not trained in Applied Mathematics as a first tier subject. People do what they are trained for and if that means solving one dynamic within an exceedingly complex system like the biosphere then that is what they will do. This is a mistake. Scientists make mistakes like anyone.

More sober minds are far more cautious and although they cannot solve the dynamic equations within the biosphere (science cannot even solve the dynamic equations within a humble bacterium) they know from thermodynamic endpoint analysis and the muller diagram that the biosphere is cooling and oscillates about a set temperature at any period of geologic time.

Further, due to natural processes like compaction and due to strong inhomogeneity within the biosphere, records of our era in a million years time will NOT show anything more that what we see in the muller diagram (fig 1-6)now, no matter how spruiked out we have become by myopic politicial pundits in scientific expert's clothing.

As time goes on from here, the sheer unpredictability of imminent climate changes will all but rule out global warming as a cause. Global warming theory is very specific about the global homogeneity of it's effects and the gradual increase in its effects with time. For example the 2006 US hurricane season will be worse than 2005 and will all but squash greenhouse warming theories because the change is occurring too quickly.