The White House's COP 21 goals: less climate idealism, more political realism | Nigel Purvis

To keep a hostile Congress out of the process, the president can only partake in internationally binding agreements with a base in existing US law

The United States' refusal to make internationally binding its ambitious pollution targets at the Cop21 climate talks in Paris isn't a sign of Barack Obama's lack of political will, but a reflection of the legal limits of his authorities and the political realities of what other nations will commit to doing.

Obama has proposed a legally binding agreement applicable to all nations without binding emissions targets. That approach isn't ideal, but it's politically and legally achievable - and a massive step forward for climate action.