God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools.
—John Muir
At dawn on August 23, 1905, a naked man stumbled out of the Sonoran Desert, in Arizona, and collapsed at the feet of a scientist who had ventured out to study biology and meteorology. The Sonoran is an exceptionally hot, dry place, where temperatures can spike to 121 degrees in midsummer, and where there is almost no humidity and little shade. The scientist, W. J. McGee, had set up camp at Tinajas Altas, a collection of small pools that provided the only drinking water for miles. The naked man looked familiar, but his body was so withered and scratched that it was difficult for McGee to believe it was the same boisterous forty-year-old he’d met only a few days earlier.
The man was Pablo Valencia, a sailor turned gold prospector. He and his partner, Jesus Rios, had introduced themselves to McGee when they stopped to water their burros at Tinajas Altas on the way to their gold claim, near the Mexican border. When they reached the claim, the men discovered they were low on water, and Valencia sent Rios back to McGee’s camp, to resupply. But in the rush of departure they failed to set a meeting place. When Rios returned to the claim, Valencia was nowhere to be seen. Rios again returned to McGee’s camp, and for five days the two scoured the desert for the missing Valencia. Valencia, meanwhile, was wandering the desert in search of a way to quench his thirst. He managed to stumble across nearly forty miles of scorched sand with nothing to drink but his own urine, which he carefully hoarded in a canteen, plus a few drops of liquid he squeezed from the body of a scorpion he’d caught.
At dawn on the seventh day, McGee heard a strange noise, “like a cow bellowing” in the distance. He rushed out of his tent to find the wasted prospector weaving unsteadily toward him. McGee and Rios took Valencia in and nursed him back to health. He “was well and cheerful,” McGee wrote, “though his stiff and bristly hair, which had hardly a streak of gray a fortnight before, had lost half its mass and turned iron gray.”
Once he returned to civilization, McGee wrote an analysis of Valencia’s extreme dehydration entitled “Desert Thirst as Disease.” It is a closely observed record of what happens to the human body when it runs out of water:
Pablo’s … formerly full-muscled legs and arms were shrunken and scrawny; his ribs ridged out like those of a starveling horse … his lips had disappeared as if amputated, leaving low edges of blackened tissue; his teeth and gums projected like those of a skinned animal, but the flesh was black and dry as a hank of jerky; his nose was withered and shrunken to half its length; his eyes were set in a winkless stare … his skin generally turned a ghastly purplish yet ashen gray … the heartbeat was slow, irregular, fluttering, and almost ceasing in the longer intervals between the stertorous breathings.
When we imagine the worst-case scenario for climate change, this is one possible image: all of us reduced to Pablo Valencias, lost in a desert without a drop to drink.
In Phoenix, Arizona, which rises from the Sonoran in “the Valley of the Sun,” not far from where Valencia wandered, such a fate is more than idle speculation. For three months a year, average high temperatures in Phoenix surpass one hundred degrees. There is less than 10 percent humidity, and rainfall averages only seven inches a year.
According to the National Weather Service, the average temperature of Phoenix has risen five degrees since 1960. Every summer, about eight hundred Phoenicians are hospitalized with heat-related problems; some of them, usually the very young or old, die. A report published by the Arizona Republic predicts that average temperatures in Phoenix could rise by fifteen to twenty degrees over a generation, due to the “urban heat-island effect”—i.e., the more blacktop highways, parking lots, air-conditioned office towers, and sports stadia that are built in the desert, the more heat will be trapped in the valley, raising temperatures to blast-furnace heights. Most credible scientists believe this shift is due to climate change.
Life in Phoenix can be viewed as a kind of experiment in extreme living, like a dress rehearsal for life on Mars, or perhaps for a future America beset by regions of extreme heat and dryness. “Having already seen an increase … in our average temperatures,” the Tucson Citizen reported in 2009, “we are at ground zero for climate change.”
When there is a lot of moisture, trees grow thick rings; when it is dry, the rings become thin. Looking at wood samples from around the West, paleoclimatologists from the University of Arizona have been able to track the region’s long history of droughts, some of which lasted for twenty to thirty years.
About a thousand years ago, the Hohokam Indians settled in the Salt River Valley, just outside present-day Phoenix. Using stone hoes, they scraped an ingenious irrigation system out of the desert—185 miles of canals that watered crops on two hundred thousand acres. As Jared Diamond showed in his book Collapse, irrigation entails a number of risks; most important, if a society becomes reliant on irrigated agriculture, it will suffer disproportionately when hit by drought. The Hohokam tribe’s population grew to an estimated 250,000 at its peak in the 1400s. But by the 1500s, archaeological evidence shows that the Hohokam began to quit their large settlements and scatter. Scientists conjecture that it was a lack of water, perhaps a “megadrought,” or a combination of drought and flood, that led to their demise.
In the 1580s, tree rings show, a severe drought extended from California to the Carolinas. More recently, a Southwestern drought that began in the late 1940s ran until 1957. President Eisenhower declared New Mexico a disaster area, Arizona suffered from forest fires, trees began to die off, and ranchers were forced out of business.
Signs indicate that Arizona forests, stressed by rising temperatures, are dying again. During a drought in 2002, the Rodeo-Chediski wildfires—the first started by an arsonist, the second by a stranded motorist—combined in central Arizona to scorch 467,000 acres, an area the size of Phoenix. Fed by high winds and tinderbox-dry woodlands, it was the worst forest fire in the state’s history, and it set off a soul-searching debate. Scientists were concerned about the health of Arizona’s ecosystem, politicians and environmentalists battled over logging, and the fire helped usher in controversial policies, such as the Healthy Forests Restoration Act, which President George W. Bush signed into law in 2003.
In the aftermath of the fires, insects moved in, causing further damage to the trees. Some experts fear that if the trend continues, the forest ecosystem of Arizona could reach a tipping point and collapse.
Studies show a steady decline in precipitation across the Southwest in recent decades. Climate models for the region have predicted a deepening strain on water supplies in coming years. Some say the change could lead to aridity akin to that experienced during the Dust Bowl.
In 2007, Dr. Richard Seagar, of the Lamont-Doherty Observatory at Columbia University, analyzed what nineteen global climate models projected for the future of the Southwest. The models showed the region will become more arid this century as a consequence of rising greenhouse gases. Seagar also studied historical records and discovered that Southwestern droughts usually resulted from the cyclical variations in tropical Pacific Ocean temperature. During El Niño events (a periodic warming of the eastern Pacific), the Southwest typically has more rain and floods, while during La Niña events (the cooling of the eastern tropical Pacific), there is typically below-average precipitation. The recent drying of the region is likely due to a series of La Niñas since the 1997–98 El Niño, but it is also probably due to emerging climate change. According to Seagar’s report, “human-induced aridifications” will become noticeable in the first half of this century.
I asked Seagar if he really believed that “a perpetual drought” was possible in the Southwest, as he had written. He shrugged and replied, “You can’t really call it a drought because that implies a temporary change. The models show a progressive aridification. You don’t say, ‘The Sahara is in drought.’ It’s a desert.” If the models are right, then the American Southwest could face a permanent drying out. The effects of El Niños and La Niñas will continue to be felt, but the wet years will become less wet while the dry years will become more dry.
“We are very confident about the realism of these model projections,” Seagar said. “Federal and state governments need to start planning for this right now.”
Australia, the driest inhabited continent in the world (Antarctica is drier), has felt the effects of climate change earlier than most other nations, and its experience holds lessons for places such as the American Southwest and equatorial Asia and Africa. At first, Australians reacted to shifting conditions with stubborn refusal to change, but as weather patterns became increasingly extreme in the early 2000s, they had no choice but to resort to innovative solutions.
Goulburn, New South Wales, Australia’s oldest inland city, is usually a lush green from an annual wash of twenty-six inches of rain. With a population of twenty thousand, Goulburn sits 120 miles southwest of Sydney, in a pastoral region that celebrates its heritage with the world’s largest cement sculpture of a sheep, “the Big Merino.” But, in the first decade of the twenty-first century, Australia suffered the worst drought in its recorded history.
By 2002, 99 percent of New South Wales—the country’s most populous state, located on its southeastern flank—was suffering from a lack of water. By late 2006, average rainfall in South Australia was the lowest since 1900. That year, Goulburn saw only fourteen inches of rain, and its rolling hills turned a depressing brown. By late 2008 and early 2009, temperatures hit 109 degrees in Melbourne and 114 degrees in Adelaide, the highest on record since the 1950s. It was so hot that railroad tracks buckled, wildfires sparked and burned out of control, power plants were idled due to a lack of water, and, unable to rely on air-conditioning, people resorted to wearing clothes they had cooled in the freezer.
Communities in the outback were devastated. Livestock markets were overwhelmed by ranchers trying to unload sheep and cattle that they could no longer afford to feed. Production of Australia’s three main crops—wheat, barley, and canola—was cut by 60 percent. Rice, a thirsty crop that Australia usually produced at a rate of 720,000 tons a year, for export to Asia, was almost wiped out: farmers harvested only 18,000 tons of rice in 2008. In some areas of the country, the price of water increased sevenfold.
Between 2001 and 2006, 10,500 families quit farming. Others succumbed to even darker despair. “Every four days a farmer in Australia is committing suicide,” said Charlie Prell, a fourth-generation Goulburn farmer. “I haven’t contemplated that myself, but it destroys the soul.”
The Murray-Darling River Basin is known as Australia’s “food bowl.” The Murray-Darling is also the country’s most important river system, transecting the country’s southeast and drawing from a watershed roughly the size of Spain and France combined. In the winter of 2006, tributaries of the Murray-Darling stopped flowing altogether. Although flows resumed late the following year, some fifty thousand farmers were affected, food prices skyrocketed, and inflation loomed.
By early 2008, rains returned to parts of eastern Australia and even threatened to flood some towns. But the Murray-Darling remained in drought, and experts fretted over the long-term repercussions. Some climate models predicted that the trend will continue, and that rainwater flowing into the basin will decline 70 percent by 2030. Many Australians feared that their hot, arid decade, what they call the Big Dry, was “the new normal.”
The Big Dry may have been caused by a combination of shifting weather patterns, such as El Niño and La Niña, and the southern oscillation (changes in air surface pressure). In 2010, Australian researchers blamed climate change, writing in the journal Nature Geoscience that the Big Dry was likely due to “anthropogenic [man-made] climate shift.”
Whatever the precise cause, the effects of the drought were greatly worsened by poor planning, outdated infrastructure, and an unwillingness to adapt to changing conditions. Industry was reluctant to change its practices, and rural irrigators vied with city dwellers over water rights. Aborigines feared a “cultural genocide” if the drought forced them out of the bush.
In 2002, farmers were using so much water from the Murray River that it no longer reached two big lakes that flow into the Indian Ocean. As a result, the lake levels dropped, evaporation accelerated, and the remaining water began to accumulate silt and salts. By early 2009, the lakes had sunk to a meter (3.2 feet) below sea level. Further evaporation could expose mud on the lakes’ bottoms to the air, which would release sulfuric acid and a host of poisonous metals into the atmosphere. If this happens, the lakes will turn into what experts have termed irrecoverable “toxic swamps.”
One option is to flood the dying lakes with seawater, to prevent acidification—a drastic measure that would destroy the freshwater ecosystem, disrupt bird migrations, and leave behind a salty residue. “It will end up being a dead sea,” said Dr. Paul Dalby, an independent Australian water consultant. “The options are toxic swamp, dead sea, or pray for rain.”
In a 2009 speech in Atlanta, Georgia, Dalby warned the United States, “Australia is where America could be in a few years…. Climate change is not necessarily a slow and gradual process. There are valuable lessons to be learned from the Australian experience. You can be forewarned and forearmed about how to deal with [climate change] before it arrives, and perhaps not go through so much of the pain that we had.”
One positive consequence of the Big Dry, he said, was that Australian farmers had learned new tricks. They now cover their crops with mulch and use underground irrigation systems to reduce evaporation. More significantly, farmers won the right to use a certain amount of water free, and a trading system now allows them to sell or buy those rights (called usufructuary rights) from each other. This market-based approach allowed resources to go to the most productive use. Profitable growers could use more water, while farmers with marginal yields could still make a living by selling their water. The allotments shift, depending on the weather. In some areas, irrigators are restricted to 18 percent of their allocation during the drought.
Australian vintners, who export some $1 billion worth of wine a year, have been especially innovative; as grape supplies drop, prices have risen overall. Water is reserved for older vines, which produce more profitable grapes. Newer vines are shorn of all their leaves, wrapped in bandages, and kept barely alive with minimal irrigation. When more water is available, the newer vines are allowed to flourish.
Australia has yet to reconcile that while it is the driest continent, it remains one of the world’s biggest exporters of “virtual water,” or the water used to grow exportable crops. Invented by Professor John Anthony Allan, of King’s College, London, virtual water is a way to assess how much water is used to produce commodities. The water used to grow wheat, for example, is said to be “virtual” because once the wheat has been grown and is shipped to market, it no longer contains the actual water used to raise it. Measuring virtual water helps judge which crops are best suited to a given climate. Cotton, rice, corn, and alfalfa are water-intensive crops and are not as well suited to arid regions as are fruits and nuts.
Though new regulations in areas such as virtual water await political action, Australians took steps to reinvent their irrigation system. In 2009, Australia’s prime minister, Kevin Rudd, launched a $1.3 billion plan to limit the amount of water extracted from the Murray-Darling Basin, buy water rights from farmers, begin monitoring water use, integrate ground and surface water supplies, impose rationing, raise water prices, ban car washing and garden watering, and invest in water infrastructure.
“For the first time the cities are focused on their worries about the future water supply,” New South Wales Senator Bill Heffernan said in 2006. “Everyone has taken for granted that you turn the tap on and water comes out. I think they now can see that that might not necessarily be the case.”
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In the United States, the relationship between climate change and water supply has not become a politically salient topic. During the Bush years, Congress bickered over legislation aimed at reducing greenhouse gases, such as the carbon cap-and-trade proposal, which would put a price on carbon emissions and allow permits to emit the gases to be auctioned. Cap and trade is the mechanism most favored by the Obama White House for limiting carbon emissions. In March 2009, the EPA administrator, Lisa Jackson, released an official opinion stating that global warming poses a danger to public health. Congress began to lay the groundwork for legislative changes, which many in the GOP contended were based on flawed science. The conflict made a consensus impossible, and in July 2010 legislation designed to limit global warming died in the US Senate.
Despite the political gridlock, the scientific consensus is that global warming will profoundly affect the water supply in coming years and will force people to make difficult decisions about how to manage it. The demands of urban and rural users and the ecosystem will have to be balanced. As the population soars, we will need to ensure long-term food and energy supplies. To adapt to new conditions, we will need to develop new strategies and technologies.
Many of the water policies of the twentieth century will become obsolete in the twenty-first. But before addressing new approaches for the future, I went to the desert West, to see how we collected, transported, and used water in the past.
Nations have traditionally responded to a lack of water by building hydro-infrastructure, from digging simple ditches to erecting vast dams, to capture runoff in wet periods and store it for times of need. The next conceptual and technical leap was to devise ways to move water from its source (a river, lake, or aquifer) to where it was in high demand (a farm, a factory, a growing city). In America, especially in the West, grandiose schemes to relocate water supplies via man-made rivers—aqueducts or pipelines—have long been an obsession. More often than not, such “water conveyance” schemes have proven controversial. The steady growth of population and climate change will only sharpen the disagreement.