IPCC-report 2007

The newest world climatic report of the UN
(IPCC report 2007, I, II, III) leaves no doubt:

those already to be observed climatic changes go back to the greenhouse gas emissions caused by humans. Their concentration in the atmosphere has risen since the industrialization around more than 50% (only CO2 around 35%) - with a strongly growing tendency. Without immediate radical reduction of the emissions the development will have serious consequences as per IPCC report.

Summary for Policymakers (pdf) Working Group I, II, III and IV