Associated Press: Gov. Arnold Schwarzenegger, his counterparts in 12 states and regional leaders from four other countries signed a declaration Wednesday pledging to work together to combat global warming, a move Schwarzenegger said will help push heads of state to curb their nations’ greenhouse gas emissions. The document was signed on the last day of an international climate summit organized by the California governor, who hopes the two-day event will inform U.N. negotiations in Poland next month on …