Economist: AS A senator, during his campaign for the presidency and in his inaugural address, Barack Obama repeatedly pledged to reduce America’s dependence on foreign oil and to tackle global warming. On January 26th he made what he called ‘a down-payment’ on those pledges, signing two executive orders concerning greenhouse-gas emissions. The move signalled a break with George Bush’s foot-dragging and hinted at grander things to come. The first order instructed officials to come up with a …