* California is projected to grow by 8 million people
* Southern California is expected to grow by 4 million more people.
* Los Angeles County currently has about 10 million people and will add another 1 million over the next quarter century.
DROUGHT / TEMPERATURE
Even if California gets heavy El Niño rains this winter, the current drought has delivered a wake-up call to state leaders. The message? Our current water habits are unsustainable.
For example, downtown Los Angeles currently experiences about a week of extremely hot weather a year, Hall said.
"By mid-century that increases to about three weeks of extremely hot weather," he said.
Some areas, like the Pasadena, Sylmar and Riverside will see more than a month of additional extreme heat a year.
The bad news is that warmer winters will cause more of it to fall as rain instead of snow. That means the snowpack in the Sierra Nevada mountains will shrink, possibly by 30 percent.
The snow pack supplies about third of the water for the entire state, state climate scientist Elissa Lynn said. It typically gives California a steady flow of water in drier months as the snow gradually melts.
"As we lose that snowpack we lose a good portion of our water supply for the spring and summer," Lynn said.
To cope, the state will need to rethink how it stores and distributes moisture from winter storms.