Timing isn't everything but it sure helps. After the mid-term elections, the mood in climate circles was getting pretty grim. We faced the prospect of a Republican-dominated House and Senate overturning emission controls, ramming through Keystone XL and elevating a climate denier (James Inhofe) to chair of the Senate Environment and Public Works Committee. Already there was talk that upcoming UN climate negotiations were dead on arrival.
In this context, the U.S.-China climate deal is a badly needed piece of good news. It signals that Barack Obama is willing to expend political capital fighting for his climate legacy.
It makes it harder for Republicans to break Obama's promises.