If anyone can be optimistic — even cheerful — about addressing climate change, it's Bill Nye.

During a recent lecture to a full house at Stanford's Memorial Auditorium, Nye brought the signature charisma of his television program, "The Science Guy," to the seemingly intractable global problem.

Bellowing jokes, circling the stage and pumping fists, he urged massive citizen mobilization around safeguarding the planet, discarding arguments that it's too hard, too abstract and too unsettled.

"What we've got to do, dare I say it, is change the world," Nye shouted out during the May 5 Cubberley Lecture hosted by Stanford Graduate School of Education. "To change the world, you have to believe you can, and be optimistic."

Nye, superstar entertainer, educator, engineer and scientist, has been traveling the country promoting the message of his new book, Unstoppable: Harnessing Science to Change the World. At Stanford, he also addressed questions of science and environmental education during a conversation with GSE faculty members Bryan Brown, associate dean of student affairs, and Nicole Ardoin, associate professor of education.

The crowd, numbering nearly 1,800 and including local teachers, children and Stanford students, faculty and alumni, also had the opportunity to ask questions and get books signed.

The Cubberley Lecture is the GSE's signature public forum, established in 1937 and dedicated to shedding new light on current issues in education. GSE Dean Daniel Schwartz kicked off the event, which this year was co-sponsored with the Heising-Simons Foundation.

"I've been fighting this kooky fight for 20 years. The science [on climate change] is settled. The science is not the problem," Nye said. "The problem is the denial … that is keeping the United States from taking action."

He said just as the people of the so-called Greatest Generation brought all of their resources to bear during World War II, youth today need to commit to a full-scale fight for the planet.

"Everybody at that time got involved," Nye said as the iconic Rosie the Riveter "We Can Do it" poster was called up on the screen behind him. "Everything was associated with winning the war. And they did."

"We can do this," he rallied.

Nye disputed claims that it's impossible to convert completely to renewable energy, remarking that the Solutions Project, a renewable energy initiative co-founded by Stanford Professor Mark Jacobson, has already charted a path to doing so.

"You could run in circles screaming about all of this but it won't be effective," Nye said —running in circles. "We could go completely renewable by 2050 if we decided to do it."

Science, Nye said, is essential to help us get there. "We use science to solve problems and to make things," he said.

But, he added, there's a lot of bad information out there. Responding to a question from Ardoin about the many places children learn science — in school but also in parks, at home, in museums and from TV, among others — Nye said it's important to make sure kids can discern truth from fiction. The skills of today's learners, he said, need to include how to sift through and critically think about information.

Brown, whose own research delves into how to communicate and teach science in urban schools, introduced the challenges teachers face with making time to teach science, when testing in elementary years turns the focus solely to math and reading.

"When I'm king of the forest, science everyday in every grade," Nye said to cheers.

The joy of discovery

Nye described how he knew his show was being used in schools to teach science so learning objectives were laid out when writing episodes. "Try and think clearly about what you want to get across," he said. "In science education, you have to show then tell."

He also encouraged not shying away from the complex. "When people say dumb it down, it just makes me crazy — or crazier. You don't want to dumb it down. You want to empower," he said. "You want everybody to feel that joy of discovery."

And you also want to appreciate the small steps to learning. "Not every moment has to be an a-ha moment," he said. "Not every technology is going to be disruptive. Don't pressure yourself to always have amazing new things. Incremental advances are good."

Bringing more girls and women into the sciences should also be a priority, Nye said, as it doubles the number of people who can tackle these problems, and raising living standards for women and girls benefits the environment.

To motivate major action on climate change, Nye encouraged optimism but recognized another effective mobilizer: fear.

"Being a little scared is not bad," he said after Ardoin, who also holds an appointment at the Stanford Woods Institute for the Environment, asked how he strikes a balance between making people feel afraid and making people feel like there's an opportunity to actually change the world. "In World War II, people were terrified."

Nye encouraged the audience to not back away when it seems no one understands the magnitude of climate change.

"In science education or environmental education, you can't get discouraged or give up," he said. "It takes repetition, and after a while, people get it."

The discussion with the audience touched on the presidential election, how to better bring low-income people into solutions on the environment and membership in the Planetary Society that Nye heads. The evening ended on a light note with the 8-year-old daughters of Ardoin and Brown having the final question: "What's your favorite science joke?"

Nye, who moonlighted as a comedian when he was just starting out in engineering, laughed as he shared the one about a neutron and proton getting a drink at a bar. The neutron asks the bartender what he owes.

But before Nye could get the punchline out, the audience roared: "For you, no charge!"

With a last fist pump in the air, the house lights were turned on and a line formed for Nye to sign his books.