SAN FRANCISCO – Gov. Arnold Schwarzenegger signed legislation yesterday that imposes the nation's first cap on greenhouse gas emissions and challenges Californians to temper energy consumption. The measure, aimed at curbing global warming, is expected to have political and practical implications, from increasing pressure for federal action from the Bush administration to accelerating new technologies that could deliver fuel-saving cars, power plants, refineries and factories. “It will begin a bold new era of environmental protection in California that will change the course of history,” the Republican governor said during a bill-signing ceremony in San Francisco. It was attended by a...