With climate change in the news, it's a good time to contemplate the unique position the Republican Party occupies in the global climate change debate.

In a recent post, Jonathan Chait described it this way:

Of all the major conservative parties in the democratic world, the Republican Party stands alone in its denial of the legitimacy of climate science. Indeed, the Republican Party stands alone in its conviction that no national or international response to climate change is needed. To the extent that the party is divided on the issue, the gap separates candidates who openly dismiss climate science as a hoax, and those who, shying away from the political risks of blatant ignorance, instead couch their stance in the alleged impossibility of international action.

That's about right. But it's worth digging a little deeper into just why and how much the GOP is an outlier on this issue. We can glean some insights from a large-scale survey of global opinion on climate change released last month by the Pew Research Center.

Partisan differences over the urgency of climate change are not unique to the US

There's no doubt that the climate issue is split along partisan lines in the US.

That 48-point spread is crazypants (and, in large part, driven by anti-Obama sentiment on the right).

However, the US is not the only country in which partisanship is an indicator of concern over climate change. The same pattern shows up in Australia, Canada, Germany, and the UK.

The overall numbers are higher and the spreads are narrower, but the partisan split exists everywhere. In fact, according to Pew, it exists in every country except Poland, where conservatives are more concerned about climate change than liberals. (No idea how to explain that; I welcome theories from more Poland-literate readers.)

Other demographic differences show up across numerous countries — young people are more concerned than older, women more concerned than men, nonwhites more concerned than whites — but to my eye those are just the same partisan differences in different guises. All things being equal, young, female, and nonwhite people are more likely to skew left.

In short: Climate change is politically polarized everywhere. The polarization in the US is different in degree, but not in kind.

Overall concern over climate change is (roughly) inversely proportional to emissions

It should probably come as no surprise that people in the countries with the highest emissions have the lowest concern over climate change. That means the US ranks fairly low and China weirdly low.

Most of this makes sense. Latin America and Africa are poor and uniquely vulnerable to drought (with which they are already struggling). The EU is, generally speaking, more politically left than the US.

But I'm not sure how to explain that China number on the left, which is down 23 percent from 2010. It's doubly odd since the Chinese government has steadily been taking climate change more seriously over those five years. And a much larger number of Chinese people say climate change is harming people now, so ... maybe they just have much more serious problems? Maybe now that the government is taking it seriously, ordinary citizens feel like they can turn to other things? Again, theories are welcome.

Regardless, there is a loose correlation between the amount of carbon emitted in a country and its emissions, as this interactive chart shows:

I suspect the explanation here is not, as Pew implies, that countries with high emissions have a financial interest in downplaying climate change. Rather, emissions are a proxy for wealth; poorer countries are more vulnerable to climate damage and thus more concerned.

Anyway, to summarize the story so far: The US has, relative to global median, low overall concern about climate change and a high partisan spread on the issue, but in neither case is the difference extreme or discontinuous, certainly not enough to explain the GOP's unique political posture on the issue.

And in another way, the US is very much like other countries.

In almost every country, support for action on climate change exceeds concern

Here's a strange — and, I think, absolutely central — fact about global opinion on climate change: Regardless of their stated level of concern over climate change, large majorities in almost every country support doing something about it. Specifically, in 37 out of the 40 countries Pew surveyed, the number of people who support limiting carbon dioxide emissions as part of an international agreement exceeds the number who think climate change is a serious problem.

As you can see, the spread is exceptionally wide in China (53 percentage points), but it's pretty wide everywhere. The only exception is Brazil, where everyone is gripped by urgency, probably thanks to a combination of recent extreme weather events and high-profile political announcements.

So what's going on here? Why is it almost universally true that more people support action on climate than deem it a serious concern?

I'm just speculating, but my guess is that concern has to clear a higher bar than support for policy. Concern is very personal; it evokes an implicit ranking. Is climate a serious concern relative to sick family members, late paychecks, or hungry kids? Is it going to harm me, any worse or any sooner than possible layoffs or health problems? It's pretty far down most people's list of concerns.

But it's a thing everyone seems to agree is a problem, so, yeah, sure, the government should do something about it. In a sense, people deputize their governments to be concerned for them.

Anyway, just a theory.

So in all these countries — US, China, India, across the EU — majorities support participation in international agreements and domestic limits on greenhouse gas emissions. And most governments reflect that fact, with internal disputes centering on policy: how fast to move, how much to spend, and what technologies to favor.

But not in the US. Unlike any other industrialized country (with the possible exception of Australia), the US has a political party that simply rejects the whole enterprise.

So we're back to our original question: Why, if US opinion broadly reflects global opinion, is one of its two parties such an outlier?

The denialist tail is wagging the climate dog

It's not that Republicans voters reject climate action — as we saw, majorities support it! In fact, it's only a faction of Republicans who oppose putting limits on carbon emissions.

The phenomenon visible here is what skews the polarization numbers cited earlier in this post: The most committed and ideologically extreme 40 percent (or so) of the GOP is very strongly committed to climate denial and small-government purism.

In a parliamentary democracy, Tea Party Republicans would probably have their own far-right splinter party, working in coalition with a center-right party that took climate change seriously; that's roughly the situation in EU countries. But in America's goofy presidential system, there are only two parties that matter. So the Tea Party took over one of them.

And this is where the US differs from other developed democracies: Not that many more of its people, or even more of its conservatives, are opposed to action on climate change, but rather the far-right faction that is opposed has leveraged its intensity and generous funding to completely occlude the center-right on this issue (as on many others).

Put more simply: There are lots of Republicans who take climate change seriously and want to do something about it, but they have virtually no representation among elected Republicans at the national level. The climate-denialist tail is wagging the GOP dog. As David Brooks laments in his latest column:

[O]n this issue the G.O.P. has come to resemble a Soviet dictatorship — a vast majority of Republican politicians can’t publicly say what they know about the truth of climate change because they’re afraid the thought police will knock on their door and drag them off to an AM radio interrogation.

Brooks is a bit delusional about that "vast majority," but he's not wrong about the thought police. Deviation on this issue is swiftly punished by a well-funded primary from the right.

So that is where we stand: While Obama joins the world's top emitters in a struggle to address what is commonly seen as a pressing global problem, the radicals dominating one of America's two political parties do everything they can to sabotage the negotiations. They haunt the Paris climate talks like the grumpy alcoholic uncle at the family reunion, shouting and stomping upstairs as everyone looks around nervously, hoping he won't come down for a drink.

Except in this case there's a nontrivial chance the uncle will be running the household in a few years.