Here's a lengthy article from the German Speigel which discusses the influence of politics on the IPCC report as well as bias of the IPCC itself. The IPCC is supposed to be composed of unbiased scientists but it appears that politicians have a large say in the final report. The head of the IPCC is not above emotionalizing the issue of global warming to suit his own biases.
Here's a lengthy article debunking the famous Mann Hockey Stick data which was first used by the IPCC and set off much of this hysteria. Just like the fraudulent data about the harm caused by power lines and Alar, these "scientists" give us a bad name.