There are three things we know about man-made global warming.
First, the consequences will be terrible if we don't take quick action to limit carbon emissions. Second, in pure economic terms the required action shouldn't be hard to take: emission controls, done right, would probably slow economic growth, but not by much. Third, the politics of action are nonetheless very difficult.
But why is it so hard to act? Is it the power of vested interests?
I've been looking into that issue, and have come to the somewhat surprising conclusion that it's not mainly about the vested interests.
They do, of course, exist and play an important role; funding from fossil-fuel interests has played a crucial role in sustaining the illusion that climate science is less settled than it is.
But the monetary stakes aren't nearly as big as you might think. What makes rational action on climate so hard is something else -- a toxic mix of ideology and anti-intellectualism.
Before I get to that, however, an aside on the economics.
I've noted in earlier columns that every even halfway serious study of the economic impact of carbon reductions -- including the recent study paid for by the anti-environmental U.S. Chamber of Commerce - finds at most modest costs. Practical experience points in the same direction.
Back in the 1980s conservatives claimed that any attempt to limit acid rain would have devastating economic effects; in reality, the cap-and-trade system for sulfur dioxide was highly successful at minimal cost.
The Northeastern states have had a cap-and-trade arrangement for carbon since 2009, and have seen emissions drop sharply while their economies grew faster than the rest of the country. Environmentalism is not the enemy of economic growth.
But wouldn't protecting the environment nonetheless impose costs on some sectors and regions? Yes, it would -- but not as much as you think.
Consider, in particular, the much-hyped "war on coal." It's true that getting serious about global warming means, above all, cutting back on (and eventually eliminating) coal-fired power, which would hurt regions of the country that depend on coal-mining jobs. What's rarely pointed out is how few such jobs still exist.
Once upon a time King Coal was indeed a major employer: At the end of the 1970s there were more than 250,000 coal miners in America. Since then, however, coal employment has fallen by two-thirds, not because output is down -- it's up, substantially -- but because most coal now comes from strip mines that require very few workers.
At this point, coal mining accounts for only one-sixteenth of 1 percent of overall U.S. employment; shutting down the whole industry would eliminate fewer jobs than America lost in an average week during the Great Recession of 2007-09.
Or put it this way: The real war on coal, or at least on coal workers, took place a generation ago, waged not by liberal environmentalists but by the coal industry itself. And coal workers lost.
The owners of coal mines and coal-fired power plants do have a financial interest in blocking environmental policy, but even there the special interests don't look all that big. So why is the opposition to climate policy so intense?
Well, think about global warming from the point of view of someone who grew up taking Ayn Rand seriously, believing that the untrammeled pursuit of self-interest is always good and that government is always the problem, never the solution.
Along come some scientists declaring that unrestricted pursuit of self-interest will destroy the world, and that government intervention is the only answer. It doesn't matter how market-friendly you make the proposed intervention; this is a direct challenge to the libertarian worldview.
And the natural reaction is denial -- angry denial. Read or watch any extended debate over climate policy and you'll be struck by the venom, the sheer rage, of the denialists.
The fact that climate concerns rest on scientific consensus makes things even worse, because it plays into the anti-intellectualism that has always been a powerful force in American life, mainly on the right.
It's not really surprising that so many right-wing politicians and pundits quickly turned to conspiracy theories, to accusations that thousands of researchers around the world were colluding in a gigantic hoax whose real purpose was to justify a big-government power grab.
After all, right-wingers never liked or trusted scientists in the first place.
So the real obstacle, as we try to confront global warming, is economic ideology reinforced by hostility to science. In some ways this makes the task easier: We do not, in fact, have to force people to accept large monetary losses.
But we do have to overcome pride and willful ignorance, which is hard indeed.