California air regulators updated the rules of a key climate program on Friday in a move widely protested by environmental groups who said the changes would weaken the program and undercut efforts to curb planet-warming emissions. The oil industry, meanwhile, said the program will still hinder efforts to bring down energy costs in the notoriously expensive state. Democratic Gov. Gavin Newsom and the Legislature last year reauthorized the state’s cap-and-trade program through 2045. The program sets a declining limit, or “cap,” on total greenhouse gas emissions in the state from major polluters. Companies must reduce their pollution, buy allowances from the state or other businesses, or fund projects aimed at offsetting their emissions. Similar programs exist across Europe and Asia, and California's system is linked with others in Quebec, Canada and Washington state.…