Thinning Fog Hurts Calif. Redwoods Iconic shroud down about a third, but it's not climate change By Will McCahill, Newser Staff Posted Feb 15, 2010 7:33 PM CST 15 comments Comments Redwood trees in Muir Woods, north of San Francisco. (Wikimedia Commons) (Newser) – The fog that famously shrouds the northern California coast has thinned by about a third in the past century—terrible news for the state’s famous redwood trees, which are nourished by the moisture. Cool air coastside and warm air inland create the fog, and scientists say a less dramatic difference in recent years has meant less fog. Climate change at work, surely? Not so fast, says one of the researchers behind the study, published in this week’s Proceedings of the National Academy of Sciences. “There’s no clear evidence for that at this point,” James Johnstone tells USA Today.