Maintaining an empire is hard work. You gotta pick a random little country to kick the shit out of once in a while or else the other little countries start getting ideas. /s
We've done that for 70 or 80 years. Like the saying goes, "do what you love, and you'll eventually become a global hegemon, weilding your influence like a club and keeping your boot on the neck of the majority of the planet, both economically and militarily."
The US government is a major factor in determining what gets done about global warming. If the USA gets locked into antidemocratic fascism and climate change denial it will exacerbate global warming everywhere. That's what the Republicans promise.