Experts say global warming will substantially affect California in about 20 years. They´re warning the state is particularly vulnerable because of its coastline, its climate and its dependence on Sierra Nevada snowpack for water and hydroelectricity.

It will mean more fights over water throughout the West. It means a shorter ski season in the Sierra, and poorer habitat for endangered salmon.

It may mean more wildfires and more floods. Extreme heat waves, easier spread of diseases and increased air pollution all could imperil health.

Oceans could rise up to 3 feet — swamping San Francisco Bay estuaries and endangering pumps sending freshwater from the Sacramento-San Joaquin River Delta to the Bay Area, San Joaquin Valley and Southern California.