Obama pledged $3B by 2020.
http://www.nbcnews.com/politics/white-house/why-trump-seeing...
Quote: "To help developing countries switch from fossil fuels to greener sources of energy and adapt to the effects of climate change, the developed world will provide $100 billion a year". And further: "Developed countries won inclusion of language that would up the ante in subsequent years," Chris explains, "so that financial aid will keep ramping up over time."
Or straight from the agreement: "Agreement shall set a new collective quantified goal from a floor of USD 100 billion per year, taking into account the needs and priorities of developing countries"
While that's $100B/yr from the "developed world" as a whole, we all know by the example of NATO what that _really_ means.
NATO members absolutely should spend what they agreed to spend, but we aren't forced to spend 3.6% of our budget on defense because they don't. That's something we choose to do, and we could stop if we wanted to.
I'm certainly not going to argue about your personal opinion based on "we all know" versus what the US has actually pledged to give.
So now the only avenue available to address the issue is re-negotiation of the agreement. Assuming the world leaders do actually want to save the climate, and not just bilk the US out of $100B/yr, they have no choice but to negotiate.