Interesting that this is being discussed on a day when a the UN's top climate official has come out and said what needs to be said : "wealthy nations are shirking their duties."
Rich nations must lead on climate change: UN official
He rightfully criticized the long range targets of the US and Japan for 2050. You and I know that by 2050 they'll not be worth the paper they're written on. Governments will have changed, policies will have changed and the ones that set the policies will no longer be in office. Heck, we could have been nuked by then.
Politicians know that by setting such long range targets, no one's going to hold them personally accountable for them actually coming to fruition but they'll get the benefit of the brownie points now for implementing the idea. They can't lose but know they look good spouting empty promises. It's depressing!