SAN FRANCISCO (Reuters) - A second official has quit the California Air Resources Board in a dispute with Gov. Arnold Schwarzenegger over the pace of implementing California's landmark law to fight global warming by capping greenhouse gas emissions. Catherine Witherspoon, executive director of CARB, resigned on Monday, four days after CARB Chairman Robert Sawyer was fired by Schwarzenegger. The governor criticized the air board for voting for a delay in enforcement of new air quality standards in the San Joaquin Valley and was concerned CARB was not pushing hard enough on air pollution.

Witherspoon, however, said she quit because Schwarzenegger's staff was trying to slow implementing measures spelled out in AB 32, the global warming law passed last year to reduce carbon dioxide and other heat-trapping gases in California by 25 percent by 2020.

"Every signal the board got from the governor's office staff was, 'Slow down, don't hurt industry, don't get ahead of us on greenhouse gases,"' Witherspoon said in an interview with the San Francisco Chronicle.