The newest columnist at The New York Times is Bret Stephens, a 43-year-old Never Trumper and the former editor-in-chief of the The Jerusalem Post. The Times picked him up from The Wall Street Journal, where he helped edit the opinion section. Five years ago, Stephens won the Pulitzer Prize for commentary.

Stephens mostly writes about foreign policy, but for more than a decade, he has also weighed in on climate change. In the best world, the world where his views resemble Theresa May’s or Angela Merkel’s, he could be a terrific asset to the Times’ climate-starved editorial section, the most important opinion page in journalism. An American conservative who understands modern climate science is a rarity.

That may be too much to hope for. After he was hired, some critics labeled Stephens a “climate-science denier.” Stephens rejects this charge, but in fact his views are not even so coherent as to be ruled denial. Instead, without him ever acknowledging it, his opinion on climate change has evolved considerably over time. The only constant is his repeated reassurances to the reader not to worry: It’s the environmentalists who are wrong.

Stephens hasn’t written a column for the Times yet, but he has revealed what presuppositions he brings to the job, leaving behind hundreds of columns at the Journal. On Wednesday, he gave an exceptional interview to Jeff Stein at Vox. Here’s a tidbit:

Stephens: Since 1880—and I’d have to look it up—but according to the IPCC [Intergovernmental Panel on Climate Change], we’ve had about 1.7 degrees of rising temperatures.

The best scientific evidence suggests temperatures are rising, and the best scientific evidence suggests man-made anthropogenic carbon emissions have some substantial thing to do with that.

However, does that mean the trend will continue forever? We don’t know. Does this mean we will reach the upper bounds of what climate scientists fear? We aren’t sure. There are uncertainties in all of this.

There is an astonishing leap between the second and third paragraph. Stephens is arguing the following: The meteorological data shows that the world is getting warmer. Anthropogenic carbon emissions are causing that warmth, just as scientists have been warning for decades. But if we keep emitting carbon emissions, or do anything to limit our release of them, well, then, who knows what will happen?

This is wishful thinking. If we keep emitting carbon dioxide, the world will keep warming, thanks to the same basic chemistry that got us here. Greenhouse gases allow the warm rays of the sun to pass through them toward Earth. After those rays hit the surface, some of their energy bounces back into space in the form of infrared light. But greenhouse gases don’t allow that infrared light to pass through, reflecting it back toward the surface and trapping heat in the climate system. In a nutshell, this is the problem of global warming.

Scientists have not updated their understanding of those facts in 30 years. They have expanded them, learning from the geological history of past climates that adding even more carbon to the atmosphere will not eventually reverse this trend. The more CO2 in the atmosphere, the warmer the planet gets.

Yet this is not even what makes this passage astonishing. By admitting that “the best scientific evidence suggests man-made anthropogenic carbon emissions have some substantial thing to do with that,” Stephens is reversing a once-dearly held position that climate change was a mass neurosis among liberals.

“Last week marked the 20th anniversary of the mass hysteria phenomenon known as global warming. Much of the science has since been discredited,” he wrote on July 1, 2008. Since the hottest year on record was 1998, he said, climate change had been disproven altogether. (1998 was an El Niño year, which are often unusually warm, no matter the underlying climate trend.)

Later, in another column, he wondered if the climate concerned were driven by the “totalitarian impulse.”  

“For the anti-Semite, the problems of the world can invariably be ascribed to the Jews; for the Communist, to the capitalists. And as the list above suggests, global warming has become the fill-in-the-blank explanation for whatever happens to be the problem,” he wrote. (This column has since disappeared from The Wall Street Journal’s website.)

Nine years have passed since the publication of his “mass hysteria” column. All but two of those years them have been warmer than 1998. Six of them have set new records for being the hottest ever measured: 2009, 2010, 2014, 2015, and 2016. Our current annum is set to be the second-warmest ever measured. And every major recounting of the global temperature trend since 2008 has found a steady, four-decade-long warming trend.  

Stephens recognizes some of these realities now, but he never cops to the fact that his views had ever been different. In a 2015 column, he said that temperatures were rising but suggested the consequences of that change would be minor. (The relatively small amount of warming so far has already disturbed Arctic ecosystems and overwhelmed the U.S. coastal-flooding insurance system.)

So, today, when Stephens concedes that that “temperatures are rising,” and the greenhouse effect is real, you have to wonder: When did he change his mind? And why does he still doubt that warming will continue?

Later in the Vox interview, he seems to admit that some climate mitigation might make sense:

The best argument made on behalf of climate mitigation strategies is even if there’s a small chance your house catches fire, you take out insurance. That’s perfectly sensible. And you can make a perfectly sensible argument that even if we’re not 100 percent sure we’re facing a catastrophic climate future, we should take out a host of insurance policies to mitigate carbon emissions.

But then the intelligent question is: “How much are you paying for insurance?”

I think a risk-avoidance model makes a lot of sense when thinking about climate change. But Stephens’ point here is incomprehensible: We are barely paying anything right now. The most substantive climate policy in the United States is a tax credit for renewable energy that is set to expire in the next decade.

You can’t talk about climate policy only in metaphor: You have to use numbers. And when it comes to numbers, energy and climate experts say that far more policy is needed to keep global temperatures below two degrees Celsius of warming by 2100. For instance, we would have to halve fossil-fuel production in the 2020s. And then we would have to halve it again in the 2030s. And then we would have to start pulling carbon dioxide out of the air.

Those estimates may be unattainable—honestly, that’s kind of the point of putting them out there—but you can’t ignore the chasm between our current policy and something resembling a reasonable insurance policy.

I’ll stop going point-by-point. But you have to wonder: Does Stephens care about updating his audience, just as he once updated his excoriating views on the existence of global warming? Or does he care more about showing that environmentalists are weak thinkers, even as the facts shift beneath him?