The Yosemite wildfire that is threatening to take out San Francisco's utilities now has some of the planet's biggest and oldest living things in its crosshairs: Firefighters are digging in around two groves of giant sequoias—about three dozen in all—taking the precautions of setting sprinklers and clearing brush amid dry conditions that could leave them vulnerable. "All of the plants and trees in Yosemite are important, but the giant sequoias are incredibly important both for what they are and as symbols of the National Park System," says a park spokesman.
The fire, which is about four miles away from the trees, has expanded so rapidly that the AP reports that it now has its own weather pattern, increasing its unpredictability. Strong winds and difficult terrain are complicating firefighting efforts, and about 4,500 structures are also threatened. The fire has devoured some 200 square miles, and was just 7% contained last night. (Read more Yosemite National Park stories.)