So the report is published and the verdict is out: we're "very likely" the cause of climate change.

"Very likely" (at least 90 percent probability) is strong language for climate scientists and a tougher stance since the last report was published in 2001 which judged the link between humankind and global warming as "likely" (between 66% and 90% probable)

The 21 page report published today "Climate Change 2007: The Physical Science Basis", is the "Summary for Policymakers" and the first of 4 parts to be released this year.

"If you see the extent to which human activities are influencing the climate system, the options for mitigating greenhouse gas emissions appear in a different light, because you can see what the costs of inaction are," Dr Rajendra Pachauri, the IPCC chairman told delegates in Paris.