And yes, this directly informs his climate denialism. Via Media Matters:
While CO2 does indeed play a role in photosynthesis, the idea (frequently touted by industry front groups) that this process somehow provides an unlimited buffer to the addition of massive amounts of carbon to the atmosphere is simply absurd, as is the idea that humans are incapable of severely damaging their environment.
Some will no doubt consider this to be unworthy of attention and discussion, as Limbaugh (in order to avoid accountability for his disinformation) likes to hide behind the fig leaf that he is only an “entertainer” and has no real political power. This is quite obviously false. Limbaugh is seen by many as the face of conservatism in the United States.
For more on the problematic coupling of antiscience religious sects and climate denialism in the American scientific and political discourse, see Yes, Sarah Palin IS a creationist and Yes, Roy Spencer IS a creationist.