I feel Federal government should work to limit pollution that is directly harming the environment. If "State A" pollutes, "State B" will feel the effects. I'll give one real life example. States outside of Ohio were allowing farm run off into the watershed which eventually made its way into the Maumee river. When the river drained into Lake Erie it caused algae blooms. It was so bad the tap water was undrinkable.
The problem is not all pollution has such a noticeable cause and effect. I am of the opinion that much of these global warming measures do nothing other than move money around.
Some of these measure actually make more pollution. Ethanol fuel has been debunked for years, but they won't kill it because it is politically dangerous. You risk losing votes from farms and money from their lobbies. That is a perfect example of why these things should not be subsidized.
You have your own perception of what is "directly harming the environment". If you studied more you might change you opinion of what harms the environment, what harms it more severely, and what harms it in relatively irreversible ways.
Some people are not capable of a level of comprehension that lets them understand effects that can't be explained to young children. Hence it's important to have competent public science bodies that are trusted by the public.
Government is not a weather control program; they have other obligations.
If we get right down to it, the US government shouldn't be much more than a military, a postal service, and customs/imports office.