At the upcoming U.N. climate conference, most of the world’s major nations will pledge to make significant reductions in greenhouse gas emissions. But serious doubts remain as to whether these promised cuts will be nearly enough to avoid the most severe impacts of climate change.
Anything is better than nothing. If we (as humanity) come out of the Paris talks with any global progress, that's a good thing.
That said, I'm personally pessimistic about long term continued progress. I'm an engineer in the electric industry. The impacts to the electric system caused by adding intermittent generation (wind and solar) aren't linear. Adding one wind turbine is easy. Adding a hundred thousand is harder. Trusting that something that doesn't exist today will save us somewhere down the road is risky to me.
Today the only reason we're seeing coal use drop is because of fracking. How we bridge from there to less use of natural gas, I don't know. It's either energy storage, which doesn't exist on the scale necessary, or nuclear, which is politically untenable. So I'm pessimistic. Short term advances will be lauded but can't be used as a basis for long term changes to the generation mix.