David Letterman, former Late Show host, will return to television (temporarily) this October when he hosts an episode of National Geographic’s Years of Living Dangerously.

This time last year, producers David Gelber and Joel Bach reached out to Letterman, who had just retired from his hosting duties a few months prior, to come onto their new National Geographic show. The show centers on the issue of climate change and humanity’s efforts to curb its effects, a topic that Gelber and Bach had noticed Letterman show particular interest in while speaking with scientists on Late Night. They extended an offer to Letterman, who eagerly said yes.

In the time since that announcement, Letterman took a trip to India to film the episode on how India goes about providing energy to its vast population, which includes multiple arrays of solar panels.

In a new promo for the series, a scruffy, sweatpants-wearing Letterman is seen walking among a series of solar panels, contrasting them to the “coal-fired, dangerous smoke-belching generating plants” that currently provide so much of the world’s energy. He then learns that perhaps the panels aren’t as safe as he thought. Check out the promo below.

Season 2 of Years of Living Dangerously, which will also include guest hosts like SNL’s Cecily Strong and Arnold Schwarzenegger, is set to premiere on National Geographic on October 30th.