Environmental activist Bill McKibben urged older people to take action on “a crumbling planet [and] a crumbling democracy” during an interview Wednesday at the Stanford Center on Longevity’s Century Summit.

The Century Summit is a two-day hybrid conference bringing together academics, experts and practitioners to discuss the implications of longer lifespans.

The interview with McKibben by Peabody Award-winning producer Davia Nelson, was part of a series of sessions focusing on intergenerational relationships and activism as a critical element of purposeful living at any stage.

McKibben founded Third Act, an organization of older people working to slow climate change and protect democracy, after he got tired of hearing that young people would have to save the planet.

“There are 79 million of us over the age of 60 in this country,” said McKibben, explaining his motivation for creating the year-old organization. “We all vote. Washington pays huge attention to us.”

Perhaps most crucially, McKibben said, “79 percent of the assets in this country belong to people in the Boomer or Silent Generations.”

“There are 79 million of us over the age of 60 in this country. We all vote. Washington pays huge attention to us.”

Bill McKibben, Third Act founder

A major component of Third Act’s planform is to force major banks to stop making loans to coal, gas and oil companies.

Speaking to the question of what different generations can bring to the table, McKibben said that young people have the “overwhelming moral authority” on the climate change issue.

“If we don’t fix this,” the job of every single young person “will be emergency response” to the destructive effects of climate change, he said.

Older people have the skills and resources — such as large portfolios that they could pull out of the major banks if they continue to fund fossil fuels — to help younger people effectuate change.

Older people are also better positioned to take the fall when large-scale climate protests lead to arrests.

Although McKibben clarified that risking arrest is only one of Third Act’s tools, he asked: “Past a certain point [in life], what the hell are they going to do to you?”

As for the generations’ perspective on each other, McKibben has seen “an extraordinary sense of relief on the part of young people that their elders are backing them up.”

As for Third Act members, he said, “we are on the edge of being the first generation that leaves the world a worse place than we found it,” so older people need to get involved.

“Your legacy is what you leave to the people you love,” he said.