on the larger scale of things humans tend to deal well with environmental catastrophes, it isn't a malicious entity that they have to fight, it's just shit that happenned
Besides when fossil fuels run low it will be physically impossible for humans to increase carbon emissions. It will just get absorbed by plants and plankton and transferred randomly across the surface of the planet. Us in 1st world countries won't have to worry if we don't overpopulate, even then if you had the intelligence enough to get rich you don't have to worry about a thing.