See if you can spot the problem in comments President Trump made about climate change during a conversation with reporters on Tuesday, after The Washington Post’s Philip Rucker asked whether he was thinking about climate change.

“I think about it all the time, Phil. And, honestly, climate change is very important to me,” Trump replied. “And, you know, I’ve done many environmental impact statements over my life, and I believe very strongly in very, very crystal clear, clean water and clean air. That’s a big part of climate change.”

Perhaps we should have suggested you spot the myriad problems with the response. Starting, obviously, with his suggestion that environmental impact assessments for construction projects have any bearing on the subject at hand.

More important, Trump’s suggestion that clean air and clean water are “a big part of climate change” is accurate only with a remarkably generous interpretation of his comments. Climate change is a function primarily of the release of gases such as carbon dioxide and methane, largely from fossil fuel combustion or extraction. Those gases enter the atmosphere and absorb heat, preventing it from escaping into space or even radiating it back toward Earth. There are other problems with emitting vast amounts of carbon dioxide, including that oceans absorb an enormous amount of it, leading to ocean water becoming more acidic, but the primary problem is that the presence of more heat-trapping gas in the atmosphere — the greenhouse effect — is increasing temperatures globally.

Environmentalists often describe greenhouse gas emissions as air pollution. The Supreme Court, in the 2007 case Massachusetts v. Environmental Protection Agency, ruled that carbon dioxide emissions could be regulated under the pollution prevention regulations of the Clean Air Act. But, again, ascribing this use of “clean air” to Trump’s linking air quality to climate change is really, really generous.

As we’ve noted before, Trump instead conflates “climate change” with “environmentalism” broadly and embraces a distinctly 1970s-era argument for what environmentalism entails. Clean air and water were indeed focal points of the early environmental movement, leading to legislation such as the Clean Air Act, which vastly reduced air pollutants like smog and particulate matter, no doubt saving millions of lives. But over the past 50 years — in part because of that success — the threat posed by increasing temperatures has become a much more urgent concern.

Just for the sake of time, we’ll ignore the fact that even Trump’s repeated insistence that he wants the cleanest air and water in the 1970s sense has been undercut by the policies and regulations he has opposed as president. A quick review of the record, though, suggests another reason the president talks about clean air when asked about climate change: He may not actually understand the mechanism that is warming the planet.

He has talked about carbon dioxide emissions a number of times as president (generally using the colloquial shorthand of “carbon”), but generally only when reading prepared remarks. When he announced in June 2017 that the United States would withdraw from a landmark international pact aimed at addressing climate change, he talked about carbon dioxide emissions in the context of China.

“Fourteen days of carbon emissions from China alone would wipe out the gains from America and — this is an incredible statistic — would totally wipe out the gains from America’s expected reductions in the year 2030,” Trump said, reading from a Teleprompter.

Setting aside the fact that the Paris accord from which he was withdrawing the United States was meant to lower China’s emissions, close observers of Trump will notice a tell in that sentence. There’s that aside, that “incredible statistic” interjection that is generally an indicator in a speech that Trump is reading something for the first time. In other words, there’s little reason to think that Trump thoughtfully included that data point in the speech he himself wrote; had he done so, his emphasis could have simply been written into the remarks.

During the campaign, Trump mostly talked about carbon dioxide emissions as a way to pooh-pooh Democrats and former president Barack Obama. Trump would almost always talk about carbon in the context of the “carbon footprint,” a measure of how much a person is contributing to climate change that was more popular about a decade ago.

Obama “talks about the carbon footprint and then he flies a really old 747 that spews out all sorts of [stuff] to Hawaii, right?” Trump said in a speech in December 2015. “The carbon foot — what happened to the carbon footprint?”

At other points, Trump would lump this “carbon footprint” argument into a complaint that he couldn’t use hair spray anymore because it was bad for the ozone layer — another archaic reference to past environmental fights.

Here he was in January 2016, again disparaging Obama.

“So he talks about the carbon footprint, okay, and how important the carbon footprint is, I’m not supposed to use hair spray in my hair because it affects the ozone,” Trump said. “Now it fits in an apartment that is totally sealed, but it goes up and it affects the ozone. I don’t think so, personally. But you know, there’s a lot of money being laid on this in that sense.”

When congressional Democrats introduced the Green New Deal, aimed at establishing benchmarks to accommodate climate change in economic planning, Trump disparaged it, oddly, in the context of the “carbon footprint,” as though that was an equivalent term to carbon dioxide emissions.

He also wildly misrepresented what was proposed but, again, that’s an aside.

In a speech at a Republican Party fundraiser in April, he did the same thing.

“You have no idea how expensive it is to make” wind turbines, he said. (He has attacked wind turbines for years, a result of his opposition to a proposed offshore wind farm he worried would ruin views from a golf course he owns in Scotland.) “They’re all made in China and Germany, by the way, just in case you — we don’t make them here, essentially. We don’t make them here.”

(That’s not true. In fact, during the 2016 presidential campaign, he briefly offered tepid support for wind turbines — when an Iowa voter asked whether he would support subsidies that aided a local turbine manufacturer.)

His remarks then turned to the “footprint.”

“And by the way, the carbon and all of the things flying up in the air, you know, the carbon footprint?” he continued. “President Obama used to talk about the carbon footprint and he’d hop on Air Force One, a big 747 with very old engines, and he’d fly to Hawaii to play a round of golf. Now, you tell me, the carbon footprint. But that’s the way it is.”

At no point has Trump ever indicated that he understands the connection between emissions and climate change. He came close in a tweet in September, mentioning emissions reductions in the context of climate — but then continued on to talk about air pollution.

He has at times bragged about the United States’ reduction in greenhouse gas emissions, as he did in prepared remarks in July, although that’s mostly as a way to defend his record. (“We’re doing a very tough job and not everybody knows it,” he said then.) He has never used the term “greenhouse gas,” according to the index of his comments at Factba.se. He was a signatory to a public statement in support of addressing emissions back in 2009 — but that was on behalf of the Trump Organization. Several months later, he publicly disparaged the fight against climate change (and somehow again looped in the ozone layer).

So we end where we begin, with uncertainty that Trump knows what climate change is, what it constitutes and what powers it. There’s certainly a political motive for his not raising the subject; climate change is viewed through a sharply partisan lens, and many Republicans, like Trump, simply dismiss it out of hand as a priority.

To be fair, though, we didn’t include Trump’s full comments about climate change on Tuesday. Here’s how he continued his line of thought when asked if he thinks about climate change.

“I also see what’s happening with our oceans, where certain countries are dumping unlimited loads of things in and they float,” Trump said. “They tend to float toward the United States. I see that happening and nobody’s ever seen anything like it and it’s gotten worse. But, no, it’s very important to me also. But I want clean air and clean water would be number one and number two.”

In other words, no. He doesn’t really think about climate change.