Gov. Brown's Biggest Climate Foe Isn't Trump. It's Car-Loving Californians

California is convening an international summit this week to push for global action on climate change. As the Trump administration has rolled back federal climate policies, California has partnered directly with other nations and cities. On Monday, Gov. Jerry Brown set the stage by signing a new state goal for 100 percent clean energy by 2045. But if California is going to reach its ambitious climate change targets, the state will have to tackle its toughest challenge yet: cars. Transportation is the state's top source of carbon emissions and those emissions are on the rise.