BBC: Alistair Darling’s speech marks the first time that a Chancellor of the UK Treasury has set a budget for carbon, as well as for the myriad pots of money that a government commands. So now, the country has a “legally binding” target: to cut greenhouse gas emissions by 34% with respect to 1990 levels by 2020. Mr Darling’s adoption of the figure proposed in December by the Committee on Climate Change, the government’s advisory body, was expected – anything less would have been a …