The central problem for those who promote the idea of man made global warming is the earth’s temperature record – on almost all time scales.
In the last decade, there has been no clear warming trend (as the UK Met Office and IPCC’s own figures demonstrate). In the last century, much of the warming occurred prior to 1940, when human emissions of CO2 were relatively small compared to today. During the post-war economic boom (when one would have expected the temperature to rise) the world cooled, from the 1940s till the mid-70s (again, this is evident from accepted data used by the IPCC).
Temperature records and the kyota agreement