10/24/2012 02:08 pm ET Updated Oct 25, 2012

Letterman Bashes Obama, Romney For Avoiding Big Issues, Fears For His Son's Future (VIDEO)

Watching David Letterman transform from an ironic wise-ass to a concerned father over the years has been truly fascinating. On Tuesday night's episode of "Late Show," Dave expressed extreme disappointment with Obama and Romney for avoiding the issues that he believes truly matter to future generations.

Talking to guest Rachel Maddow, he blasted the candidates for the total lack of global warming discussion during the presidential debate. "That bothers me, because I've got an 8-year-old son. What's the world going to be like when he's 65 years old?" (Letterman has been an outspoken opponent of fracking.)

But he didn't stop there. His voice noticeably rising, he went after the two men for neglecting gun control issues. "I understand people who have guns. I understand people who hunt. I understand people who want to protect themselves. I understand that," Letterman said. "But I am sick and tired of mass shootings on college campuses and in theaters."

"Of course they're not going to talk about gun control because it's a hot button issue," he went on. "Well, I'm interested in hearing what the future might be for my son. Four and a half hours, I don't get any sense that it's going to be any better for him."

Despite his newly serious tone, Letterman had previously been more lighthearted about the presidential election. He'd had quite a bit of fun at Mitt Romney's expense, feigning outrage over a series of weeks that Romney refused to appear on his show. And as recently as last month, he hosted President Obama on his show, although most of that discussion was devoted to attacking Romney's then-recent "47%" comments.

Maddow offered a more optimistic take than Letterman provided, pointing out that media was being democratized and that young people, such as Letterman's son, would be more likely to perform independent research when they reach voting age. But that didn't quell Letterman's current outlook.

"Substantively speaking, what will the world look like when I'm gone and my son's still here? I got no answers for that."