Love it (on a still Saturday morning) or hate it (any day of the week in the summer), fog is a crucial part of life in Northern California. Now a new study on coastal fog by researchers at the UC Berkeley has shown a significant decrease in the North Bay's iconic weather phenomenon. That's potentially very bad news for our friends the redwoods, which get an estimated 30–40 percent of their moisture from fog.

Dr. James A. Johnstone, one of the principal authors and a faculty member at the school's environmental science, policy and management department, says the study originally came out of a general inquiry into the climate of Northern California and its impact on redwood forests, but found that local cloud-ceiling height reports from airports dating back 60 years painted an interesting picture of their own. "Turns out there's an amazing record of fog every hour over the last 60 years," he says. "It looks like fog is a third more common before 1925 than in the recent decade." Or, in other words, we now emerge out of the fog an average three hours earlier in the day than we did a hundred years ago.

It's not clear at this point whether the decline in foggy weather is simply a regional circulation change or if it is yet another ominous symptom of human impact on the environment. Regardless, the redwoods rely on a raised humidity level in the forest canopy in order to stay hydrated. "Fog helps them to conserve water throughout the dry summer season," says Johnstone. "I would say it's a subject for some concern, but not for alarm or panic at this point."

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