Mayor Eric Garcetti spoke during a lunchtime plenary at the VerdeXchange/FutureBuild, a conference on sustainability, business and public policy, on Tuesday at the L.A. Hotel Downtown on Figueroa. He urged all departments in the city to look at everything through a lens of environmentalism.

“Los Angeles had a sustainable past, going all the way back to the original adobe structures that started the city,” he said to the 375 people in the audience. “We paved that over. We need to get back to our roots by, for example, turning our faces towards the river instead of turning our backs on it.” The mayor was just one of roughly 80 speakers at the two-day conference, which started Monday morning.

“Plant kale and they will eat kale,” said Ron Finley, Co-Founder of LA Green Grounds, during a morning breakout session called: “Space Changers: Guerrilla Planning and Urban Acupuncture.” It dealt with grass-roots advocacy.

Finley spoke about health and gardening in urban areas. Daveed Kapoor, director of Utopiad, said the city needs more fully separated bike lanes such as those planned for the My Figueroa project. And until then, “People aren’t going to drive safely around bikes until the police start giving drivers citations,” he said. “That’s how people learn.”

Other speakers talked about alternative fuel sources, high speed rail and construction. “The most sustainable building is the one you don’t have to build,” said Reuben Lombardo, a project manager with Spectra, a Pomona-based firm that restores old buildings.

Also on display were videos of robots which extrude resins and place concrete rebar to build new houses in days instead of months. Jim Andersen, Chief Executive Officer of Baru Investments, spoke about how young people today reject suburban living in favor of smaller apartments in city centers. “They’re willing to pay a premium for a smaller space that’s near where they want to be,” he said.

“By going to all these different sessions, I learn about stuff not normally in my wheelhouse,” said Santa Monica Mayor Pam O’Connor. “For example, my city isn’t a Port City, but the economic benefits coming out of the Port of Los Angeles—as well as the pollution—impacts us all.”

Indeed, that was a major theme of the conference: understanding and cooperation among seemingly disparate municipalities is the key to reducing pollution.

“The most important work is not to listen to people like me” said Garcetti. “It’s to meet the people around you and to make commitments to change.”