BBC: California has stepped up its attempts to reduce greenhouse gas emissions by setting tough new targets for 2030.
Governor Jerry Brown issued an executive order to bring down emissions to 40% below 1990 levels, in the next 15 years.
The US state was already one of the most ambitious in its previous targets and has forced companies to pay for their carbon pollution.
Mr Brown said the new target must be met for the sake of future generations.
He called the plan "the most aggressive benchmark...