LOS ANGELES — Gov. Jerry Brown issued an executive order Wednesday sharply speeding up this state’s already ambitious program aimed at curbing greenhouse gas emissions, saying it was critical to address “an ever-growing threat” posed by global warming to the state’s economy and well-being.

The order, announced early Wednesday morning, was intended as a jolt to a landmark 2006 environmental law requiring an 80 percent cut in greenhouse gas reductions by 2050, compared with 1990. Under Mr. Brown’s order, the state would have to get halfway there — a 40 percent reduction — by 2030.

Mr. Brown said this tough new interim target was essential to prod the energy industry to act and to help the state make investment and regulatory decisions that would assure that goal was not missed.

The order is the latest effort by Mr. Brown to position California as a leading force in the world’s effort to address climate change — and position himself as a leader of that effort as he enters his final years in public office. It also is an aggressive turn in what already was one of the toughest programs in the nation aimed at reducing greenhouse gas emissions.