There are people out there who are genuinely skeptical of the science. Those are not who must be fought as they make up almost none of the campaigners across the media and internet trying to discredit the science. The rejectionists can, not completely but mostly, be lumped into a couple categories - the prominent professionals (a few scientists, "think tanks", and political types like Marc Morano and Senator Jim Inhofe) and self-selected common folk who are ignorant on the science and highly fearful of government action (local examples found at sayanything and dakotavoice).
This is not about silencing alternative theories. This is about firmly saying 'enough!' to "alternative theories" that range from scientific nonsense to repeatedly debunked ideas to unsubstantiated claims of fraud and hoax to hate of government. As Dr. Peter Gleick recently described,
Deniers don't like the idea of climate change, they don't believe it is possible for humans to change the climate, they don't like the implications of climate change, they don't like the things we might have to do to address it, or they just don't like government or science. But they have no alternative scientific explanation that works.
Just looking at the showing-as-I-write-this comments to the above-cited article exemplifies the 'tear down but build nothing.' There are claims the temperature record is not reliable, citation of the supposedly "bitter cold winter of 2009", mention of east coast snowstorms, accusations of skewing data, invocation of undescribed "cyclical" climate events and "oscillations", assertions there is warming but of uncertain cause, claims of conflict of interest by the writer, appeals to the sun and sunspots, and whines of condenscension.
Again, when there is something from this crowd at least approaching science it critically flawed in being either simply wrong, grossly misinterpreted, irrelevant... Still it is challenging enough, battling that pseudoscience from what is largely a PR campaign built to a significant degree from the ashes of the weapons used in the tobacco wars to dispute the smoking-cancer link. Now a wide swath of highly partisan and hyper-libertarian ideologues reflexively join the mob without even giving much thought to the science besides cranking up the hostility toward those who study it.
Quite simply these people have no credibility when it comes to climate science. You hear something between 'a-ha' and screams of bloody murder over even the smallest things they think support their case against climate science, yet accountability is generally absent when their claims and assertions of fraud are shown false. Explaining climate science now necessarily involves not just conveying the real information but also showing how wrong and misleading that anti-science crowd is.