The increase in global temperature over the last 200 years is an abnormal and alarming phenomenon, which has been very likely caused by human activities, our habits and the organisation of our societies.

This presentation, aiming at clarifying sometimes complex ideas,is an overview on global warming, on the dramatic consequences of temperature rise and the main causes of this scientific phenomenon. It also explores the role of governments and the recent political debate before Copenaghen's Conference on Climate.