No one knows. Some climate modeling suggests it might, especially if the California Current System is affected, which is certainly possible, and has been speculated about quite a lot. In the New York Times yesterday, Healy Hamilton of the California Academy of Sciences was quoted on the subject:
Dr. Hamilton said that on the Northern California coast, fog has an
influence on natural systems. But “none of our climate models can tell
us what is going to happen with fog,” she said. “So we are facing
profound uncertainties about how our coastal ecosystems are going to
Not mentioned in the article was the simple fact that many redwood trees are not in preserves, but in close proximity to various outposts of civilization, such as Mill Valley and Mendecino. The coastal redwoods depend on their ability to comb water out of fog in the summer, but if the fog was to dissipate, I would expect heroic efforts from Northern Californians to replace that water. Would it succeed? Not everywhere, but I guarantee the NorCal folks wouldn’t give up easily…though it would be difficult to duplicate the ecosystem that has grown up around this fallen tree, from Wadebriston‘s photostream.