What is this "nuclear warming"?

I don't pick up on every piece of drivel that emanates from Donald Trump's filthy mouth - many others are doing that - but some of it is just so weird it's actually fascinating (in a depressing kind of way).

Take, for example, "nuclear warming". First introduced by Trump back in April 2023, in an interview with Tucker Carlson on Fox News, Trump asserted, "When I listen to people talk about global warming, that the ocean will rise in the next 300 years by one eighth of an inch, and they talk about how this is our big problem. Our big problem is nuclear warming, but nobody even talks about it." Well, there's a good reason for that...

He mentioned it again in what critics are calling "the dumbest climate conversation of all time", an "interview" of sorts between Trump and fellow weirdo Elon Musk in August 2024. At one point in this epic of gobbledygook, Trump offered up, "The one thing that I don't understand is that people talk about global warming, or they talk about climate change, but they never talk about nuclear warming". 

Now, granted, this was the same interview in which Trump mused about rising sea levels creating more ocean-front property, and Musk suggested that the only compelling reason to ditch fossil fuels is that they will one day run out. So, we are not exactly looking at mainstream climate science here. But what is this "nuclear warming"? It was never quite explained.

Trump revisited the concept once again at the beginning of September, warming to his theme, so to speak. At a rally in New York, he first poo-poo'd global warming: "When people talk about global warming, I say the ocean is going to go down [sic] 100th of an inch within the next 400 years. That's not our problem. Our problem is nuclear warming, and we better be smart, and we better have smart people at the top who know how to deal. Because these people don't know how to deal."

So, there's a clue, right? Is this nuclear warming something to do with card games, and we need smart people who can deal well? It's still not very clear to me, and I would very much like to understand. Maybe it's related to Pierre Poilievre's dystopian vision of the Liberals' carbon tax leading to a "nuclear winter"?