Climate goals: inside California's effort to overhaul its ambitious emissions plan

In the wake of Trump's Paris withdrawal, California is taking the lead to fight emissions - and it's rethinking how to get more out of its cap-and-trade program

California has one of the world's most sophisticated and ambitious cap-and-trade programs, which are designed to provide financial incentives to big polluters, such as electricity providers and oil refineries, to lower their greenhouse gas emissions.

The complex program, which began only in 2013, is a signature component of California's plan to cut emissions in the midst of a controversial makeover by state policymakers, after they passed a landmark bill last year that created one of the world's most aggressive climate change goals: to lower carbon emissions to 40% below the 1990 levels by 2030.