The deadly heat wave of August 2003 convinced a majority of French of the dramatic impact of climate change. This article aims at presenting evidence and analysis about public perception, environmental performance, and policy development in France with regards to this major public apprehension. The French are indeed among the most concerned people in the world and the EU about climate change, and they seem more willing than others to act resolutely to mitigate it. Yet, if the performance of the French economy in terms of greenhouse gas emissions (GHS) is flattering, ambitious public policies will have to be implemented to achieve the "factor 4" objective set in 2005 (a four-fold reduction of GHG by 2050). This was precisely the main purpose of the "Grenelle environnement," which in 2007 tried to build into the law the national consensus on climate change and the sustainability of which is bound to be tested by acute economic difficulties.