Predictions suggest climate change will bring more weather extremes, increasing our risk of flooding and drought.
Lynne Nittler with the Cool Davis Initiative says that's why the group is organizing what it calls a "flash flood mob." Participants will gather on an old earthen levee outside Davis, holding up murals of angry water to draw attention to the levees' vulnerability.
But Nittler says the point isn't just about the local risks.
NITTLER: "What we're doing worldwide on this day is connecting all the different weather events happening, the climate change events, to show that it's not isolated little happenings with our weather."
A Sacramento State group is also staging a "We're Under Water" event at a nearby levee. In theTahoe area a group will be planting 1,00 sugar pines to absorb carbon dixoide. And an adventurous group will camp out by the Dana glacier near Yosemite to unfurl an "I'm Melting" banner.