Opinion Cleaning up their act

For Obama, the plan is also a step towards fulfilling a pledge from his first term, which looked unlikely after a 2010 effort at legislation was stymied in Congress. In practical terms, it will consolidate the shift from coal as an energy source towards natural gas, driven by the cheaper economics of fracking, already under way in the US. This has led to a fall in carbon emissions, which have already declined 10 per cent from 2005 levels and are still on a downward trajectory.

The US’s inaction on global warming so far has been routinely invoked by emerging economies such as China and, yes, India to justify the limited measures they have taken to cut emissions. If part of Obama’s objective is to encourage, by example, the adoption of similar emissions-reducing targets in the developing world, he will be heartened by a senior Chinese official’s announcement a day later that it would limit its carbon emissions, with specific targets written into the next five-year plan, effective 2016. Given that the US and China together account for more than 40 per cent of the world’s carbon dioxide emissions, a demonstration of their intent to address climate change could create a new resolve to negotiate a climate treaty at the next UN climate summit in Paris late next year.