Global Warming Could Slam Food Supply

Suppose the dinner on your table last night had cost 20 times what it did? Or 50 times as much?

Scientists say global warming very likely has something like that in store in the coming decades.

The agricultural abundance Americans have long taken for granted and the low food prices that go with it, they say, now face a withering enemy -- and the recent blows to California agriculture are a taste of things to come.

The threat to the state's $30 billion agriculture industry has farmers and legislators battling over differing ideas about how to deal with what climatologists tell them future temperatures in the Golden State will likely be before mid-century.

In the very short term, a number of food prices will be creeping up over the next few months as the impact of the 21-day double heat wave of 2006 works its way from withered fields to the market shelves.

In that double heat wave, Fresno County, Calif., alone suffered $85 million in beef, dairy and poultry losses. That's not surprising, as they had 20 days exceeding 100 degrees, including three consecutive days of 113 degrees.

Scientists have linked this latest heat assault to man-made global warming in a number of ways, most simply because it fit exactly the global warming pattern of more frequent and more intense heat waves predicted 30 years ago.

Scientists now calculate that man-made global warming makes the chances of events such as the deadly 2003 European heat wave, which killed more than 35,000 people, twice as likely -- and that by 2040 Europe could well experience such serious heat waves every other year.

Or take the case these past three weeks of one of America's most taken-for-granted miracles: the cornucopia of California's San Joaquin Valley. Sprinklers to wet the panting cows in the San Joaquin's massive dairy and meat farms, and fans to cool them, were not enough. Thousands of cows dropped dead in the heat.

This one valley grows nearly half of America's fruits and vegetables. You've most likely tasted some recently, wherever in the United States you are.

Not only that, the San Joaquin Valley grows 95 percent of America's apricots, almonds, raisins, olives -- and the list goes on.

"We grow over 250 different types of crops here -- lettuce for the base of your salad; you may have garlic and onions with tomatoes for the sauce for your pasta," said Liz Hudson of the Fresno County Farm Bureau, as she stood shoulder-deep in a field of dense green wheat on a bright sunny day.

But that bright sunlight, though a necessary component for the Valley's abundance, is nowhere near sufficient.

What's also vital is water, and therein lies the greatest threat.

"We're seeing the early signs of climate warming here," said climatologist Dan Cayan of the Scripps Institution in San Diego, assessing California's vulnerability. "We're very worried about climate warming."

The warming attacks in different ways. Blossoms may open weeks too soon, before insects arrive to pollinate them, and fruit trees may produce weaker crops because there are fewer cool nights, which the trees need for recovering between harvests.

The agricultural miracle of the San Joaquin Valley -- crops stretching in every direction literally as far as the eye can see -- simply wouldn't be possible if the farmers tried to pull it off with the natural weather. It only rains eight inches a year, and almost all of that in the wintertime.

What makes all the food possible is irrigation -- water brought in from far away, a large part of it from snow pack in the mountains, and distributed throughout the Valley by a vast system of irrigation canals and pipes.

Our ABC News team drove three hours up into the Sierras to Sequoia National Park to see the fast-disappearing snow pack under the towering ancient trees.

Even though the Sierras had a snowfall far above average this past winter, as did many of the western mountain regions, in most places that didn't help the valleys much because the snowpack melted weeks too soon as it has been doing for some years with global temperature rising. And snowpack provides about three-fourths of the West's water.

The trouble is, as scientists studying the change explain, water normally used to trickle out over the summer. Now, running downhill too soon, it is leaving many valleys dry by midsummer, and crops withering.

San Joaquin farmers like Dan Errotabere, whose family corporation farms thousands of acres in the San Joaquin Valley, will get through this summer. But they must strain to use every drop.

Errotabere, like most working the rich ground, metes out water to his almond trees through pressurized tanks and lines.

The water distribution station next to his almond groves looks more like what you'd expect to find in a high-tech chemical factory -- shiny, round metal flasks, three feet in diameter, sealed tight against sun and drippage, interconnected by varying sizes of pipes and supports.

"It's all contained," Errotabere said, "so the only place that water should leak out is at the drip system."

For the farmers, it's as precious as oil. We found water meters spinning at the corners of fields all over the great valley. Like oil, it's expensive.

"Water is a big piece of our farm budget" he said.

And if water becomes even more scarce, thus more costly?

"Food prices will go up," he said matter of factly.

This summer, San Joaquin growers will probably have enough water. The dams and reservoirs built around the edges of California's Great Central Valley have just enough capacity to hold one year's supply.

But computer model projections shown to ABC News by eminent climatologist Steve Schneider at Stanford University, and other calculations from California state water boards, now warn that because of global warming the mountain snowpack so essential to all the food is most likely to be not only melting out too fast in the spring, but diminishing drastically -- by as much as 90 percent, according to some computer models -- before the end of the century, well within the lifetime of today's kids.

San Joaquin farmers are famous for their adaptability and ingenuity. They have to be to wring so much for America's tables from ground that naturally gets only eight inches of rain a year, and that only in winter.

And there's the pride and responsibility they feel as producers of nearly half our fruit and vegetables.

If anyone can figure out how to deal with hard times down on the farm, supplying the bursting supermarkets in which most American kids think the food they love so much somehow just magically appears, the San Joaquin farmers can.

But even San Joaquin farmers will need the water.