My 6-year old daughter Chiara is a member of what I call Generation Hot. That's the 2 billion people worldwide who were born after June 23, 1988, the day NASA scientist James Hansen's testimony to the U.S. Senate put the world on notice that man-made global warming had begun and threatened to make Earth uninhabitable.

Since then, humanity's greenhouse gas emissions have only accelerated. Now, the young people of Generation Hot are fated to spend the rest of their lives coping with the hottest, most volatile climate our civilization has ever known.

When I think of Chiara's future under climate change, nothing concerns me as much as water. We live in California, a state whose economy and politics have been shaped by water – and the lack of it – since before the Gold Rush. It was in California, after all, that Mark Twain penned his immortal line, "Whiskey is for drinking, water is for fighting over."

Scientists project that global warming will cause both deeper droughts and fiercer floods – a fiendish paradox. Meanwhile, the laws of physics and chemistry assure that global temperatures will rise for decades to come even if emissions are reduced. The rising temperatures will, among other things, also melt snowpacks.

In California, snowmelt is the source of nearly one-third of the freshwater supply. The Sierra Nevada snowpack will shrink by 25 to 40 percent by 2050, according to the California Department of Water Resources.

The challenge for California, then, is to prepare for both more water and less. Alas, we still have a long way to go. And perhaps nowhere is at greater risk than the state capital.

Neglectful in Natomas

Stein Buer, the former executive director of the Sacramento Area Flood Control Agency, told me in 2009 that Sacramento was less protected than New Orleans had been before Hurricane Katrina. The problem, said Buer, is that the capital is "located at the bottom of a 27,000-square-mile watershed, and all that water has to squeeze by Sacramento on its way to sea."

At the moment, the only thing protecting the people, businesses, infrastructure and government buildings of Sacramento are levees made of packed earth, originally constructed more than 100 years ago. Now these same levees are shielding the government of the ninth largest economy on Earth, along with the 454,000 people who call Sacramento home.

How was this allowed to happen?

"Proposition 13 created a grow-or-die syndrome in California," said Jeffrey Mount, a geology professor at UC Davis and a former member of the state Reclamation Board, which overseas the state's levees. Proposition 13, approved in 1978, all but prohibited local governments in California from raising property taxes on existing homes – previously the localities' major source of revenue.

"The only way local governments could fund their operations has been to grow – to build more homes, add new developments, occupy more land, even risky land," Mount explained. "That has had the effect of putting more people in harm's way."

When I asked Mount to name the most vulnerable spot in Sacramento, he instantly replied, "The Natomas basin." None of the government officials I interviewed disagreed.

Maurice Roos, the grand old man of California water experts and something of a skeptic about climate change, said of Natomas, "I don't think the people who live there understand what risks they face."

Driving along the top of the levee that shields Natomas from the American and Sacramento rivers, I could easily look down on the roofs of houses below; I remember seeing a dad pitch Wiffle balls to his son in a side yard. If a flood broke through or over this levee, flooding was inevitable, and not just a little flooding.

"It's one thing to get your feet wet," Roos said. "It's another thing to have water over your house."

But here's the thing. Although the danger was understood by government officials and highlighted by local media, the expansion of Natomas rolled on.

One day, I visited a Natomas housing development called Four Seasons. Billed as an active adult community for people age 55 or better, Four Seasons promised "resort-style living" where "nature is right at your doorstep."

The copywriter might better have left out that last phrase. The Sacramento River was indeed only a half mile away, and the only things standing between it and Four Seasons were flawed, ancient levees.

But have no fear, a bubbly saleswoman named Claudia told me at the rental office: Four Seasons would be a perfectly safe place for my 77-year-old mother to live if she decided to relocate from back East.

"Are you sure?" I asked. "I read some articles that talked about the flood risks and maybe the levees aren't so strong."

Her face flushed. "It's very frustrating to see all those stories in the paper," she said, "but I assure you we wouldn't put a planned community in a place we thought was dangerous. The government just wants more money, so it's changing the rules after we did everything we were supposed to. But we are not going away, no way."

Sponges needed uphill

Some good news: In 2007, Gov. Arnold Schwarzenegger issued a flood control plan that authorized repairs for about 30 percent of the state's shoddy levees, and work is now under way for some of those in Natomas and Sacramento.

The bad news: As The Bee has reported, fixes for the Natomas levees could be delayed by the Republican-controlled U.S. House of Representatives, which is blocking funding authorization for the Army Corps of Engineers in the name of opposing earmarks. Good thinking, guys.

And remember the paradox: Along with fiercer flooding, California will also have to cope with deeper drought in the years ahead. The state's climate change adaptation plan does not mince words: "Drought conditions are likely to become more frequent and persistent over the 21st century due to climate change."

Coping with such water shortages will require California's citizens, businesses and especially its farmers to be much less wasteful in how they consume water. The state government's so-called 20 by 2020 Plan, which calls for reducing water use by 20 percent per capita by 2020 by improving the efficiency of water use, is a good first step.

In the future, California's greatest challenge will be to reduce consumption from agriculture, which accounts for nearly 80 percent of our state's water use. A second essential step is less obvious: the need to restore the vitality of California's forests and other ecosystems.

"We need our forests, especially in the mountains, to be like sponges," said Robert Wilkinson, a professor of environmental studies at the University of California, Santa Barbara, and former co-chairman of the U.S. National Climate Change Assessment. "So when there is more water coming down from the mountains, whether because of storms or melting snowpack, the trees and soil can soak up that water like a sponge.

"In the short term, that means less flooding downstream. In the long term, it means the water is stored underground and available to use later. Then, if the climate system swerves the other direction… we can rely on that naturally stored water."

Turning California's forests into water-storing sponges would take a significant investment of time and money, Wilkinson conceded – perhaps several billion dollars over 10 years. But that is no more than the state has committed for levee repairs, and it pales in comparison to the costs, both human and economic, that climate change threatens to impose in the years ahead.

"It's time to be bold," Wilkinson said. "The window of opportunity for dealing with this problem is closing fast."

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Mark Hertsgaard, who lives in San Francisco, is the environment correspondent for The Nation and a fellow of the New America Foundation. He adapted this article for The Bee from his latest book, "HOT: Living Through the Next Fifty Years on Earth."

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