At high tide, a partially submerged staircase along San Francisco's Embarcadero is an eerie reminder of the mere inches that separate dry land from water.
In 2008, the bay waters surged over the walls, flooding streets and sidewalks, much like they did in 2002. Now, with scientists telling the United Nations that sea level is rising faster than current models predicted, the flooding could happen much more often.
"Today's flood is gonna be tomorrow's high tide," said Joe LaClair, Chief Planning Officer at SF Bay Conservation and Development Commission. "So we need to get ready for those kinds of changes -- a deeper bay, a bay with bigger waves, and more frequent flooding."
California's Bay Conservation and Development Commission is in charge of making the maps that show areas in danger of flooding if sea level rises 16 inches, which is predicted to happen in 2050. But now, they say it may be sooner -- with models that account for the melting permafrost in the earth's arctic regions dumping water into the ocean and methane into the atmosphere.
Believe it or not, San Francisco's waterfront will be among the last parts of the bay shore to flood, thanks in part to careful engineering. But state regulators caution if walls like these aren't built along other parts of the Bay Area's shoreline, whole communities could wind up underwater.
Communities like Foster City -- nearly all of it in danger of being underwater by mid-century, or maybe sooner.
"There's going to be a lot of people displaced," Foster City shopper Linda Nieder said. "This is very expensive property down here."
And if you think rain cancels a lot of flights now, in a few decades the San Francisco and Oakland airports could be shutting down flooded runways with every storm.
"That's crazy, those are two major airports," Foster City shopper Briana Turk said. "So that'd be shocking if that were to happen."
State planners say levees, sea walls, and pumps will need to surround the airports -- an engineering project not to be taken lightly.
"We should take the time and do it right," LaClair said. "But we probably need to move more quickly than we thought we did."