Could 2500 of the worlds leading climate scientists be wrong?

Last week 2500 climate scientists from 130 countries signalled a warning to the world. They are now 90% certain that the global warming of 0.7 degrees celsius that has occurred over the last 100 years is directly related to the activities of mankind.

They went on to add that if we continue at this pace, the globe will warm at an accelerated pace with temperatures of between 1.1 degrees and 6 degrees being quoted. This will do irreverable damage to our planet and the species that occupy it.

In their response to the IPCC report, both George W Bush and John Howard continue to drag their heels by looking for their own solutions instead of admitting that their non co-operation of the last decade has been the wrong direction and getting together with the rest of the world and ratifying the Kyoto Protocol.

I am not sure what needs to happen for this occur? Perhaps they need to see the hairs burning on their forearms first?