Nye on HBO: "By the end of this century, if emissions keep rising, the average temperature on Earth could go up another four to eight degrees," Nye said. "What I'm saying is the planet's on f***ing fire. There are a lot of things we could do to put it out -- are any of them free? No, of course not. Nothing's free, you idiots. Grow the f**k up. You're not children anymore. I didn't mind explaining photosynthesis to you when you were 12. But you're adults now, and this is an actual crisis, got it? Safety glasses off, motherf***ers."