This year's event drew a much smaller, but passionate crowd of a few hundred science buffs and practitioners to check out the booths run by science organizations and hear speeches and live music.
Many were scientists, like Becky Mackelprang of UC Berkeley. Mackelprang says she came to fight the growing mistrust of scientists and science, not just in terms of climate change, but also things like vaccines and "fake studies" shared on social media.
"I saw these two ridiculous studies, one was that thinking makes you fat and [the other was] that bras give you cancer," Mackelprang said. "What I would love was for the average person to see that headline and say, 'That doesn't seem right to me. Maybe I need to look into that a little bit more before I share it on Facebook.' "
Sprinkled among the scientists were their admirers, including a contingent of students there to support their biology teacher, Glenn Wolkenfeld, who was also lead singer of the band that opened the event.