Look at how the counties voted. You mentioned flooding coastlines? Republicans might WANT that to happen.
Half the country are anti-intellectual, anti-science evangelical christians. The other half who acknowledge man-made climate change begrudgingly tolerates their presence.
Racism. Everything goes back to racism. The big corporations are against climate change because they see regulations as a dent in their profits. So they sell racism to the evangelicals to get their vote, while pushing the stuff they actually care about. Evangelicals have no theological reason to care about climate change one way or the other but have bought into being climate change deniers because it's on the platform along with racism. If the environmentalists had sold racism to the South instead of the rich, conservatives would be all about conservation right now.