Earlier quoted context omitted.
Do you think American voters are going to be happy about sacrificing their own well-being explicitly so that other people can pollute/deforest more? Do you think that's a platform that will win elections?
I think we should use our wealth and clout to both do better than the bare minimum in our own country and pressure other countries to do at least the bare minimum. I think our leaders should figure out how to do that while still winning elections. That does sound hard, but if the job description were only to pander, anybody could do it.
Do you want a pony, too?
Look, we're not talking about straight up charity. You can talk people into charity; despite the standard narrative, the United States is quite generous in that regard. What you're asking for is for us to reduce our standard of living explicitly so other people can pollute. That's going to be a hard sell.