It is a policy wonk’s way of saying “Up yours Donald!” And it is a way to create a legacy that Trump will have to deal with. Trump may take steps to undo this, but he will need to expend political capital to do so.
It is finally a bit of good news for humanity! Perhaps we will wake up to climate change fast enough to avoid its worst effects. The race is on and the load of poop in our pants that is Donald Trump is about to slow us down as we run that race.