Global Warming and Climate Change are very real. Conservative Activists who deny it are so clueless it's gotten to the point of comedy. That said I don't think there's really anything the US can do to make a major dent in this anymore. Other countries are producing carbon emissions at a rate close to the United States (UAE is one example) and you have bigger countries like China and India industrializing so in the near future they will be even bigger polluters than the US.
What can we do to stop this? I really have no idea.