Because it isn't just one person? And I'm being serious right now, if all you contribute and believe is that the dude who got himself elected leader of the free world is a simpleton dimwit: You are the Problem
I don’t think anyone believes that in its entirety. But if you don’t think green house gases are a problem you are, on that topic, a dimwit.
It's not hard to imagine that he did this on a whim; that's his nature. He does it all the time, including with important economic policy, such as tariffs. Impulsively making important decisions without a sound reasoning process is dimwitted behavior. Isn't it obvious that Trump is an impulsive decision maker?