People in the OT Paris Accord thread have raised some valid points about our image as a country. Our withdrawal may not change much, especially if companies and states continue the green revolution and we rejoin in ~3.5 years, but we've certainly painted ourselves as capricious and unreliable. Moreover, even if we elect someone sane - or even a string of sane people - who knows if we might get someone like Trump again?
I hope the next Democratic president and Congress willingly impose more restrictions on the executive branch. Most of the power in this country should be vested in Congress, the body directly elected by the people, and we need explicit laws that reduce the executive's power and increase accountability. That way, even if we have a lunatic in office, he or she can't inflict too much harm.
P.S. I suspect this withdrawal might increase the oppo droppo, and not just from American outlets. Putin, for all his evil, recognizes climate change and its effects on his country, most notably Siberia. Despite his penchant for chaos, this decision can't be thrilling him. Other countries' intelligence agencies might also feel freer about dropping shit now.