At the risk of repeating what I and about a million other people have already said, I'll say it again: California could learn a lot from Portland when it comes to transit and its climate-related benefits.
In the Portland metro area, transit is efficient and relatively inexpensive for riders. In the Bay Area, the most transit-rich region in California, 28 different providers don't add up to an efficient "system," and transit operators are raising already high fares.