Upton Sinclair once said, “It is difficult to get a man to understand a thing when his salary depends upon his not understanding it.”

This is the best way to summarize the mindbending results of the climate change study the Pew Research Center released on Monday, which found that more than one in two conservative Republicans—and more than a third of moderate Republicans—refuse to believe that the planet is getting warmer.

Let’s get one thing out of the way: It is a measured, observable fact that the Earth’s average temperature has been rising for the last several decades. Indeed, eleven of the twelve hottest years on record occurred between 2001 and 2011. This is not a theory about why this is happening; it is a measurable—and measured—fact that it is happening.

Yet disconcertingly large numbers of people on the right seem unable to accept it: the Pew study found that only 63 percent of moderate Republicans and 49 percent of conservative Republicans believe the climate is changing, while 93 percent of those who identify as liberals (and 90 percent of moderate Democrats) believe it. What is going on?

Another statistic from the Pew poll helps answer that question:

Only 45% of Americans (58% of Democrats, 30% of Republicans) believe that there is scientific consensus that human activities (e.g., burning fossil fuels) are causing the climate to change. This partisan confusion over why the Earth is warming has now led to a confusion as to whether it’s happening at all.

So let’s now be clear about a second fact: there is a scientific consensus on this issue. All reputable climatologists agree that human-caused (“anthrogenic”) climate change is real. Our popular confusion is the result not of an honest difference of opinion, but, to quote our Secretary of State, of a vast right-wing conspiracy.

It’s no secret that for nearly as long as scientists have spoken about climate change, energy companies have been funding conservative think tanks—CTTs in Beltway-speak—to create the impression that there is no scientific consensus on the topic. They have blitzed the airwaves and the bookshelves with pseudo-scientific fact-muddling written by non-specialists. For example, according to a 2008 study, of the 141 books denying the seriousness of environmental problems that have been published since 1972, 130 were published by CTTs or written by authors affiliated with them.

By contrast, 928 peer-reviewed articles were published in scientific journals between 1998 and 2002 adducing evidence proving the existence of human-caused climate change, and zero—zero!—were published contradicting it. If that’s not consensus, I don’t know what is. Yet it matters not a whit to the industry’s PR campaign.

And as the Pew study shows, this strategy of deliberate ignorance, obfuscation and misinformation has been abundantly successful.

During the same five-year period in which peer-reviewed believers outnumbered deniers 928 to zero, 53 percent of major newspaper stories gave airtime to “both sides” of this scientific “debate.” That’s like giving “both sides” equal time to debate the question of whether the law of gravity exists.

Who are these so-called “climate skeptics”? As described in Naomi Oreskes’ “Merchants of Doubt,” they’re not climate scientists; they’re paid political lackeys.

For example, Steven Milloy, who co-authored the American Petroleum Institute’s 1998 plan to sow doubt and confusion about climate change, is also a Fox News commentator, a scholar at the Cato Institute, and a former lobbyist for Exxon, Philip Morris, the Edison Electric Institute, and Monsanto. He holds an undergraduate degree in natural sciences and an MA in health statistics, but no PhD and no climatology credentials. Yet he’s an “expert.”

Or take Dr. Timothy Ball, a former geography professor who’s published just four peer-reviewed journal articles, none of which addressed atmospheric science. Yet CTTs such as the Frontier Centre and the amusingly named Friends of Science say he has an “extensive science background in climatology.” Ball actually said once that climate change would be good for Canada, since the weather there would be warmer—perhaps forgetting that even a small shift in climate would wipe out crops, destroy fragile ecosystems, inundate coastal areas, and decimate alpine areas and the economies that depend on them.

In short, nearly every climate skeptic been funded by the energy industry.

The CTTs themselves are just as bad: For example, as far back as 1995, the Global Climate Coalition (funded by ExxonMobil, Royal Dutch Shell, British Petroleum, Texaco, and so on) admitted in internal documents that human-caused climate change “is well established and cannot be denied,” yet it was happy to conduct a well-documented misinformation campaign that claimed “scientists differ” on the matter.

Since 1998, ExxonMobil alone has spent $22 million on CTTs, including the Competitive Enterprise Institute ($2m), Center for Strategic and International Studies ($2.4m), Annapolis Center for Science-Based Public Policy ($1.0m), American Enterprise Institute ($2.8m), Heritage Foundation ($630k), Heartland Institute ($676k) and many, many others.

And remember when Mitt Romney said, “I like clean coal!”? That was the result of twenty years of lobbying by CTTs such as the Information Council on the Environment, founded and funded by coal interests with the explicit goal of “reposition[ing] global warming as a theory (not fact)” and supplying “alternative facts to support the suggestion that global warming will be good,” particularly targeted at “older, less-educated males” and “younger, lower-income women.” (ICE was disbanded when these strategy documents were leaked.)

The delicious irony is that CTTs and their henchmen are the ones accusing honest climate scientists of gaming the data for political purposes—as if independent climatologists are part of some dark conspiracy while lackeys paid by Exxon are trustworthy and pure. Paging Mr. Sinclair! People don’t go into science for the money. This is the pot calling the glass pitcher black.

But it works, as evidenced by the absence of any climate-change discussion in this year’s presidential race. 69 percent of Americans believe climate change to be a “serious issue,” according to the Pew study, yet twenty years of propaganda have given Mitt Romney the perfect response to anything President Obama might say: I’ve got a study saying it’s not our fault.

Al Gore may have won a Nobel Prize for his efforts, but Americans are in worse shape, on this issue, than we were ten years ago. In 2001, between 67% and 77% of Americans believed (PDF) anthrogenic climate change to be real. Now, according to the Pew poll, only 42% do. That’s the kind of shift that only billions of dollars of propaganda can buy.

Then again, maybe this isn’t the right time for the Pew report. Maybe an election year isn’t the occasion to explore the deep and sinister causes of Americans’ confusion about the climate. But it sure is when we reap the effects.