We're probably six minutes into a 10-minute interview when I ask William Shatner the question that's been dogging me ever since I found out there was to be an interview.

"Ted Cruz, the Republican presidential candidate, has said that Captain Kirk is a Republican," I said. "Do you agree?"

For Shatner, this could have been an easy question. Who better to answer it than the man who played the swashbuckling "Star Trek" captain on film for nearly 30 years?

Maybe he didn't want to color the way people view his character. Maybe he was channeling the post-partisan politics of "Star Trek's" 23rd century. Whatever the reason, Shatner did a very un-Kirk-like thing: He took evasive action.

"If you could define what 'Republican' and 'Democrat' means nowadays, I might be able to enter into that discussion," he said. "But the roles seem to be mixed. And what defines a Republican and certainly what defines a Democrat is so blurred, I don't quite know where anybody's standing."

So Shatner is very reluctant to talk about politics, it turns out. But if he could cast a ballot today, chances are he wouldn't be voting for Cruz.

You see, Cruz has been a vocal critic of man-made climate change. And Shatner's biggest fear? It's that humanity won't even live to see the 23rd century because of overpopulation and greenhouse gases. In fact, Shatner is disappointed in us all for making 2016 such a letdown compared to the sunny utopia laid out in "Star Trek."

"There was all kinds of interest in flying vehicles and health and the state of the world" among science fiction writers 50 years ago, Shatner said. "That we wouldn't be melting away, into the sixth extinction. It would be a much more pleasant. Peaceful. Humane world. Than it is."

Are there any technologies that worry you? I asked.

"The technology that worries me is the old technologies," Shatner said. "The technology of uses of energy and the spilling of toxins into Mother Earth, and we're killing our Earth and nobody is irate about it enough. And not enough people are irate about it. People like yourself — young people like yourself should be screaming at the top of your lungs to the people who lead."

It's a challenge not even Captain Kirk would be able to take on, Shatner said. Kirk was the captain of a single ship. Climate change is a big collective action problem requiring the input of lots of different actors.

I later asked him whether there was any role on "Star Trek" that Shatner, looking back, would have liked to try. He joked that he might have wanted to replace George Takei as Hikaru Sulu, the USS Enterprise's helmsman. Perhaps it was a dig at Takei, with whom Shatner is said to have a contentious relationship. But it was clear Shatner is preoccupied by bigger things these days than politics, on or off the set.