Oil and gas operations in California would have to reduce their emissions of methane, a major component of natural gas, under a regulation the state proposed last week. The California Air Resources Board says the proposal would limit intentional venting of the potent greenhouse gas and require facilities to monitor for and repair leaks. Under the proposal, emissions from the state’s oil and gas sector would drop by about 1.5 million metric tons of carbon dioxide equivalents from an estimated 2.5 million metric tons of CO2 equivalents per year, based on the 20-year climate change potential of methane. The state’s proposal is similar to a regulation EPA issued in May. Though the federal rule applies only to new and modified oil and gas facilities, the California proposal would apply to existing operations, too. Oil and gas facilities are responsible for about 15% of California’s methane emissions, notes the air resources board, which regulates air pollution. A decade-old state law requires California to reduce its greenhouse gases to 1990 levels by 2020.