A tornado struck eastern Arkansas, damaging several homes and businesses, the National Weather Service said.

Around Little Rock, high winds rolled over a mobile home and damaged about a dozen other homes, and trees and power lines were down around the state. Road signs were reported bent in Johnson County, in northwestern Arkansas. A 78-mph gust was reported in the northeastern part of the state.

About 7,600 homes and businesses lost electricity when power lines went out after being hit by trees or other power lines, and the wind kept workers from making immediate repairs.

"It's kind of like a yo-yo out there," Entergy Arkansas spokesman James Thompson said.

In Ashdown, Arkansas, an 83-year-old city councilman died after lightning struck his house and started a fire. His wife was injured but survived.

In Shelby County, Tennessee, a woman died when her vehicle struck a tractor-trailer during heavy rain, officials said.

A couple in Tilton, Arkansas, suffered cuts and bruises after they left their mobile home and took shelter in their vehicle. The storm blew out the vehicle's windows -- but the trailer was destroyed, said Gerald Britton, a deputy emergency coordinator in Cross County.

Other homes in the county were also damaged, Britton said.

Lost shingles and downed fences in Lonoke County may have been caused by a tornado, the weather service said. Another tornado may have touched down in Woodruff County, where trees and power lines were down at Morton, the National Weather Service said.

Arkansas Gov. Mike Huckabee said he will declare five counties disaster areas, entitling them to state money for the cleanup.

In Mississippi, students at Lockard Elementary School in Indianola were ordered into hallways just before a tornado struck, assistant principal Valerie Simpson said. No one was hurt, but the storm caused roof damage to three buildings and blew out windows.

Winds as high as 80 mph took off roofs and otherwise damaged homes in Bolivar and Panola counties, said Lea Stokes, spokeswoman for the state emergency agency. Three people were injured in Lowndes County, where several homes were damaged or destroyed.

Students in several counties were sent home.

"Some of the trees that made it through Katrina might not make it through this," said Ceroy Jefferson, assistant superintendent for Jefferson Davis County Schools. "We just want children to be safe at home."

The storm damaged homes and businesses, toppled trees and caused power failures in parts of Tennessee, where gusts up to 70 mph were reported near Nashville.

The rough weather was caused by a storm system moving from the northwest ahead of a cold front. The main storm system was moving into the rest of the South, and other thunderstorms were possible from another system expected to be centered in Missouri.

Storms were expected through Monday.

Until this year, the record for days without recorded rainfall was set in 2000, a measly 101 days. The recording instrument for rainfall is at the Phoenix Sky Harbor International Airport, referred to as "the bucket" by meteorologists, and drier than a Sunday morning during Prohibition.

"People are sort of losing their grip," said Gary Woodard, who, as associate director of the University of Arizona Center for Sustainability of Semi-Arid Hydrology and Riparian Areas, is an expert on the region's water. " 'Did you hear it's going to rain tomorrow?' Well, actually, there's an 80 percent chance it's not going to rain. People are getting very excited about very slim chances of rain."

The drought has wreaked havoc on wildlife, which depend on the scant seven inches of rain that Phoenix gets in an average year, most of it in the three or four winter months.

"We have cactus dying from lack of water," Mr. Woodard said. "We have well-established mesquite trees that are in a lot of trouble."

Small animals are too dried out to do what comes naturally.

"None of the animals, none of the birds are having offspring this spring. No baby quail, no baby bunnies," Mr. Woodard said.

An alarming result of the drought is the condition of the air. On Thursday, Arizona's Department of Environmental Quality posted its 25th pollution advisory of the winter, a remarkable number. Last winter - the opposite of this one, with abundant rainfall - there were no such days. There is no rain to knock the dust and particles out of the air and wash them away.

"We've just had this large, dry, stagnant air mass hanging over the area since November," said Steve Owens, director of the environmental agency. "It used to be, you'd come to Arizona if you had breathing problems because of the air quality. Now, I think you'd have physicians who would say, 'Don't come to Arizona.' "

The drought seems to promise a harsh fire season. Last year, relatively heavy rains fell all winter, prompting fast growth in trees and shrubs that now sit dry and cracked. "I don't think I could have planned a better fire season," said Tom Pagano, a forecaster with the federal Natural Resources Conservation Service. "A lot of people in that business are quite worried."

The drought has not hurt the skin-care industry.

"You have to use lotion right when you're out of the shower, when your skin is still moist," said Mary Low, services manager at Arizona Biltmore Resort and Spa. "People wear sandals, so the skin on the heels of your feet get exposed to the dry air. The skin on the feet gets dry and cracked. You have to use a pumice stone and put lotion on your feet."

Another high-end refuge, Spa du Soleil in suburban Scottsdale, uses "medical grade oxygen" to infuse 87 vitamins straight into a customer's face, said the spa's director, Irene Kelly. "It really does keep your skin nice and smooth and plump and supple and hydrated," Ms. Kelly said.

Tourists love the sunshine and high temperatures in the 60's and 70's. Local residents shrug, and click on the humidifier at night.

"You get used to it, and pray every day that it rains," said Justin Hoiby, 27, an event planner overseeing a Western-themed company picnic - Pennsylvania executives racing in little covered wagons - in Scottsdale. It was Wednesday, and to the north, a huge, fat, gray-black rain cloud hung over the mountains, like a blimp over a sold-out stadium.

"I think it's going to stay to the north," Mr. Hoiby said, as the executives competed in a Wild West Olympics. "I've been watching it."

And yet, closer it came, the cloud blocking the sun and kicking up a little dust, irritating some tourists like Mary Green, 67, visiting from Chicago. "Nice for them," she said, looking over her shoulder at the grayness. "Not nice for a visitor who wants sunshine. It's not going to last, that's the nice thing."

But did it ever arrive? A few raindrops hit a forehead and a windshield. A nearby gas station attendant, Robert Roe, saw it: "It came down pretty good for about two seconds."

Jeff Grenfell, 41, a sommelier and chef, was hiking at the time. "I got a few drops," he said later.

Rain!

Not quite. None hit the bucket at the airport, according to the National Weather Service. The dry streak did not end, and a record-setting 142nd day continued, with no precipitation in the 24-hour forecast.

The record number of days in Phoenix with nothing more than trace amounts of rain (defined as less than 1/100th of an inch, but more than a drop on the forehead) is 160.

Whether that record will be broken in 19 days is unclear. Forecasters are calling for a relatively high chance - 50 percent - of rain this weekend.

Resource conflicts of this type are most likely to arise in the developing world, Reid indicated, but the more advanced and affluent countries are not likely to be spared the damaging and destabilizing effects of global climate change. With sea levels rising, water and energy becoming increasingly scarce and prime agricultural lands turning into deserts, internecine warfare over access to vital resources will become a global phenomenon.

Reid's speech, delivered at the prestigious Chatham House in London (Britain's equivalent of the Council on Foreign Relations), is but the most recent expression of a growing trend in strategic circles to view environmental and resource effects-rather than political orientation and ideology-as the most potent source of armed conflict in the decades to come. With the world population rising, global consumption rates soaring, energy supplies rapidly disappearing and climate change eradicating valuable farmland, the stage is being set for persistent and worldwide struggles over vital resources. Religious and political strife will not disappear in this scenario, but rather will be channeled into contests over valuable sources of water, food and energy.

Prior to Reid's address, the most significant expression of this outlook was a report prepared for the U.S. Department of Defense by a California-based consulting firm in October 2003. Entitled "An Abrupt Climate Change Scenario and Its Implications for United States National Security," the report warned that global climate change is more likely to result in sudden, cataclysmic environmental events than a gradual (and therefore manageable) rise in average temperatures. Such events could include a substantial increase in global sea levels, intense storms and hurricanes and continent-wide "dust bowl" effects. This would trigger pitched battles between the survivors of these effects for access to food, water, habitable land and energy supplies.

"Violence and disruption stemming from the stresses created by abrupt changes in the climate pose a different type of threat to national security than we are accustomed to today," the 2003 report noted. "Military confrontation may be triggered by a desperate need for natural resources such as energy, food and water rather than by conflicts over ideology, religion or national honor."

Until now, this mode of analysis has failed to command the attention of top American and British policymakers. For the most part, they insist that ideological and religious differences-notably, the clash between values of tolerance and democracy on one hand and extremist forms of Islam on the other-remain the main drivers of international conflict. But Reid's speech at Chatham House suggests that a major shift in strategic thinking may be under way. Environmental perils may soon dominate the world security agenda.

This shift is due in part to the growing weight of evidence pointing to a significant human role in altering the planet's basic climate systems. Recent studies showing the rapid shrinkage of the polar ice caps, the accelerated melting of North American glaciers, the increased frequency of severe hurricanes and a number of other such effects all suggest that dramatic and potentially harmful changes to the global climate have begun to occur. More importantly, they conclude that human behavior-most importantly, the burning of fossil fuels in factories, power plants, and motor vehicles-is the most likely cause of these changes. This assessment may not have yet penetrated the White House and other bastions of head-in-the-sand thinking, but it is clearly gaining ground among scientists and thoughtful analysts around the world.

For the most part, public discussion of global climate change has tended to describe its effects as an environmental problem-as a threat to safe water, arable soil, temperate forests, certain species and so on. And, of course, climate change is a potent threat to the environment; in fact, the greatest threat imaginable. But viewing climate change as an environmental problem fails to do justice to the magnitude of the peril it poses. As Reid's speech and the 2003 Pentagon study make clear, the greatest danger posed by global climate change is not the degradation of ecosystems per se, but rather the disintegration of entire human societies, producing wholesale starvation, mass migrations and recurring conflict over resources.

"As famine, disease, and weather-related disasters strike due to abrupt climate change," the Pentagon report notes, "many countries' needs will exceed their carrying capacity"-that is, their ability to provide the minimum requirements for human survival. This "will create a sense of desperation, which is likely to lead to offensive aggression" against countries with a greater stock of vital resources. "Imagine eastern European countries, struggling to feed their populations with a falling supply of food, water, and energy, eyeing Russia, whose population is already in decline, for access to its grain, minerals, and energy supply."

Similar scenarios will be replicated all across the planet, as those without the means to survival invade or migrate to those with greater abundance-producing endless struggles between resource "haves" and "have-nots."

It is this prospect, more than anything, that worries John Reid. In particular, he expressed concern over the inadequate capacity of poor and unstable countries to cope with the effects of climate change, and the resulting risk of state collapse, civil war and mass migration. "More than 300 million people in Africa currently lack access to safe water," he observed, and "climate change will worsen this dire situation"-provoking more wars like Darfur. And even if these social disasters will occur primarily in the developing world, the wealthier countries will also be caught up in them, whether by participating in peacekeeping and humanitarian aid operations, by fending off unwanted migrants or by fighting for access to overseas supplies of food, oil, and minerals.

When reading of these nightmarish scenarios, it is easy to conjure up images of desperate, starving people killing one another with knives, staves and clubs-as was certainly often the case in the past, and could easily prove to be so again. But these scenarios also envision the use of more deadly weapons. "In this world of warring states," the 2003 Pentagon report predicted, "nuclear arms proliferation is inevitable." As oil and natural gas disappears, more and more countries will rely on nuclear power to meet their energy needs-and this "will accelerate nuclear proliferation as countries develop enrichment and reprocessing capabilities to ensure their national security."

Although speculative, these reports make one thing clear: when thinking about the calamitous effects of global climate change, we must emphasize its social and political consequences as much as its purely environmental effects. Drought, flooding and storms can kill us, and surely will-but so will wars among the survivors of these catastrophes over what remains of food, water and shelter. As Reid's comments indicate, no society, however affluent, will escape involvement in these forms of conflict.

We can respond to these predictions in one of two ways: by relying on fortifications and military force to provide some degree of advantage in the global struggle over resources, or by taking meaningful steps to reduce the risk of cataclysmic climate change.

No doubt there will be many politicians and pundits-especially in this country-who will tout the superiority of the military option, emphasizing America's preponderance of strength. By fortifying our borders and sea-shores to keep out unwanted migrants and by fighting around the world for needed oil supplies, it will be argued, we can maintain our privileged standard of living for longer than other countries that are less well endowed with instruments of power. Maybe so. But the grueling, inconclusive war in Iraq and the failed national response to Hurricane Katrina show just how ineffectual such instruments can be when confronted with the harsh realities of an unforgiving world. And as the 2003 Pentagon report reminds us, "constant battles over diminishing resources" will "further reduce [resources] even beyond the climatic effects."

Military superiority may provide an illusion of advantage in the coming struggles over vital resources, but it cannot protect us against the ravages of global climate change. Although we may be somewhat better off than the people in Haiti and Mexico, we, too, will suffer from storms, drought and flooding. As our overseas trading partners descend into chaos, our vital imports of food, raw materials and energy will disappear as well. True, we could establish military outposts in some of these places to ensure the continued flow of critical materials-but the ever-increasing price in blood and treasure required to pay for this will eventually exceed our means and destroy us. Ultimately, our only hope of a safe and secure future lies in substantially reducing our emissions of greenhouse gases and working with the rest of the world to slow the pace of global climate change.