Naomi Oreskes and Erik Conway, a couple of historians of science, answer these questions and more in Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. Their answer turns out to be pretty simple: a little coterie of cranky Cold Warriors, funded by industries and right wingers, are afraid that climate science will undermine their idol: unfettered free market capitalism. So they have been willing to scheme, to lie, and to smear in the interest of undercutting the legitimacy of all science. The only thing surprising about the tale is that these people were once legitimate scientists themselves, though not in fields relevant to those they target.
Here's the authors' summary:
Oreskes and Conway document this process exhaustively. It's depressing; several generations of scientists have seen their conclusions challenged and distorted for reasons that have their origin not in the truth of their work, but because some powerful interest might have to sacrifice some profits for the common good.
What struck me about this book was the extent to which Oreskes and Conway had to explain over and over how science actually works. For a people who benefit everyday from antibiotics and the internet, we are frequently pretty oblivious to the system of knowledge that underlies our civilization. So we get reiterated elementary lessons here:
Oreskes and Conway conclude by calling for all of us to take responsibility for affirming enough scientific knowledge to get human beings on track to deal with the manifold damage our unsustainable release of carbon energy is inflicting on the planet, our island home. This isn't easy; there are loud, annoying and quite vicious opponents out there.
My emphasis. We really have no choice. Scientists have made the survival of contemporary civilized life possible. We have to listen to them when they do science.