Business Green: French president Nicholas Sarkozy last week staked his political reputation on controversial plans to introduce a carbon tax, arguing that the unpopular proposals were essential to efforts to tackle climate change and establish France as “the world leader of non-carbon energies”. Speaking in a televised address from a heat pump factory in Culoz last week, Sarkozy attempted to face down critics of the new tax, drawing parallels between the introduction of the levy and other unpopular …