When Gov. Jerry Brown arrives in Paris next week for a major international conference on climate change, he will showcase one of the world’s most sweeping programs to cut greenhouse gas emissions. California has perhaps the most comprehensive cap-and-trade program in the world, setting a limit and a price for pollution from factories, utilities and transportation fuels. The state’s 2030 goals ofgetting half of its electricity from renewable sources and reducing greenhouse gas emissions to 40 percent below 1990 levels are also among the most ambitious anywhere.