A UC Berkeley biologist says the Bay Area has lost 33% of its fog over the last 50-some years, or “basically three hours per day of fog,” in his words.  

A once highly popular anonymous Twitter account known as Karl the Fog, which lent a deadpan persona to the fog that turned into an enduring local cult hit, gave up the ghost at the end of 2019 and laid the gag to rest. Whoever was behind that account, their timing may have been prescient. (Though we do now have Karla the Fog to replace Karl.) The Examiner reports that a UC Berkeley biologist who’s been studying the fog has data indicating that the Bay Area has lost 33% of its fog since the 1950s, a troubling trend that is continuing.

Integrative biology professor Todd Dawson has studied historical fog records from coastal stations, assessing  when the fog comes in, how long it stays, and which times of the year have been foggiest, and his conclusion is clear. “We’ve lost basically three hours per day of fog,” he tells the Examiner.

“We’re really perturbing the climate system,” Dawson says. “We’re changing the way air circulates. That means that changes the way our storms behave, the severity of the storms and other things like fog formation and duration.”

Dawson is just one scientist, and these findings are not yet published in any kind of academic journal or peer-reviewed format. But he’s published plenty of research and is widely cited. And he’s surely correct that the fog is how the Bay Area retains its rich biological ecosystem of wine grapes, redwoods, Dungeness crab, and ability to sustain pretty much any kind of tree, while not receiving rainfall for two-thirds of the year. “It is truly an additional water subsidy to California’s (mostly) coastal ecosystem,” he says.

Two other “fog authorities” entertain the possibility that there’s less fog, but aren't as sure this is permanent. “Fog is an incredibly complicated phenomena,” U.S. Geological Survey program officer Alicia Torregrosa, tells the Examiner. “What happens under increased solar radiation trapping of heat…is still a very open question.”

Meanwhile, Cal State Monterey Bay professor Daniel Fernandez says the fog has actually increased the lost couple of years, but says that may just be a blip in a decades-long downward fog trends. “The several before that, there were very few fog events — way fewer,” he told the Examiner.

It's an old adage in academia that every study tends to end in “more research is necessary,” but that’s probably the case here. “The jury’s out.” Fernandez told the Examiner, “if anything, it’s probably shrinking.”

Related: Ask A San Francisco Native: Has The Fog Always Been Named Karl? [SFist]

Image: @jespr via Unsplash