Naomi Oreskes is a professor of history at the University of California San Diego and co-author of "Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming."

...I study the history of climate science, and my research has shown that the think tanks and institutes that deny the reality or severity of climate change, or promote distrust of climate science, do so out of self-interest, ideological conviction or both. Some groups, like the fossil fuel industry, have an obvious self-interest in the continued use of fossil fuels. Others fear that if we accept the reality of climate change, we will be forced to acknowledge the failures of free-market capitalism.

Still others worry that if we allow the government to intervene in the marketplace to stop climate change, it will lead to further expansion of government power that will threaten our broader freedoms.

But most Americans do not work for the fossil fuel industry, and most Americans accept that there is an appropriate role for government to protect human and environmental health. So why has the denial of climate change achieved so much traction? In my travels, I have met many, many people who have told me that they are not in denial about climate change; they simply don't know enough to decide....

...[M]any Americans cling to the idea that it is reasonable to maintain an open mind. It isn't, at least not to scientists who study the matter. They have been saying for some time that the case for the reality and gravity of climate change has been proved beyond a reasonable doubt. But there's the rub. The public seems to view scientists as the equivalent of the prosecuting attorney trying to prove a case. The think tanks, institutes and fossil fuel corporations take on the mantle of the defense.

We have to get over that flawed notion....