The only two countries who didn't join the Paris Accords were Nicaragua, who thought it wasn't strong enough and Syria which didn't participate due to civil war. Every other country signed on.
Trump is trying to pull the US out because it energizes his base which is against environmental concerns and is supported by Big Oil and such donors.
Under the Paris Accords, each country set its own goal which is voluntary. There is no penalty for not meeting the self-selected target goal. So Trump pulling the US out is largely symbolic. Which is doubly true since he was required to wait under the terms of the PA, and once he initiated withdrawal mechanism, it takes one year before it becomes effective. And that one year deadline occurs one day after the next president is sworn in. So if a Dem wins, there is no withdrawal from the voluntary unenforceable self-selected limits.