Replenish

The Virtuous Cycle of Water and Prosperity

Sandra Postel

• Publisher: Island Press
• Year: 2017
• ISBN:
  9781610917919
• Topic: Política y relaciones internacionales
• Subtopic: Política

"Nothing is more important to life than water, and no one knows water better than Sandra Postel. Replenish is a wise, sobering, but ultimately hopeful book." —Elizabeth Kolbert "Remarkable."— New York Times Book Review "Clear-eyed treatise...Postel makes her case eloquently." — Booklist, starred review "An informative, purposeful argument."— Kirkus We have disrupted the natural water cycle for centuries in an effort to control water for our own prosperity. Yet every year, recovery from droughts and floods costs billions of dollars, and we spend billions more on dams, diversions, levees, and other feats of engineering.These massive projects not only are risky financially and environmentally, they often threaten social and political stability. What if the answer was not further control of the water cycle, but repair and replenishment?Sandra Postel takes readers around the world to explore water projects that work with, rather than against, nature'srhythms. In New Mexico, forest rehabilitation is safeguarding drinking water; along the Mississippi River, farmers are planting cover crops toreduce polluted runoff; and in China, "sponge cities" are capturing rainwater to curb urban flooding.Efforts like these will be essential as climate change disrupts both weather patterns and the models on which we base our infrastructure. We will be forced to adapt. The question is whether we will continue to fight the water cycle or recognize our place in it and take advantage of the inherent services nature offers. Water, Postel writes, is a gift, the source of life itself. How will we use this greatest of gifts?

Chapter 1

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Water Everywhere and Nowhere

In water that departs forever and forever returns, we experience eternity.

—Mary Oliver

As I wound my way up Poudre Canyon in northern Colorado, the river flowed toward the plains below, glistening in the midday sun. It ran easy and low, as it normally does as the autumn approaches, with the snowmelt long gone. I was struck by the canyon’s beauty, but also by the blackened soils and charred tree trunks that marred the steep mountains all around. They were legacies, I realized, of the High Park Fire that had burned more than 135 square miles (350 square kilometers) of forest during the previous year’s drought. It was September 7, 2013, and my family and I were heading to my niece’s wedding. Tara and Eric had chosen a spectacular place for their nuptials—Sky Ranch, a high-mountain camp not far from the eastern fringe of Rocky Mountain National Park. As we escorted my elderly parents down the rocky path to their seats, I noticed threatening clouds moving in. They darkened as the preacher delivered his homily. Please cut it short and marry them, I thought to myself, before we all get drenched.

The rains held off just long enough. But that day’s brief shower was a prelude to a deluge of biblical proportions that began four days later. A storm system stalled over the Front Range and in less than a week dumped nearly a year’s worth of precipitation in some areas. The Poudre—short for Cache la Poudre—flooded bigger than it had since 1930. The torrential rains washed dead tree trunks down the hillsides into the raging river below. One canyon resident wrote that the blackened logs “looked like Tinker Toys amid the river’s mad rush.”¹

The threefold punch of drought, fire, and flood wreaked even worse havoc in neighboring mountain canyons, including that of the Big Thompson, a river renowned for the devastating flood of 1976. While that flood took 144 lives, it was relatively localized. This 2013 flood was vast, covering most of Colorado’s Front Range and affecting not only high-elevation towns from Boulder to Estes Park—a number of which experienced a 1-in-500-year storm—but the heavily populated plains from Colorado Springs north to Fort Collins. Though by no means the deadliest, with eight lives lost, it became one of the costliest flood events in Colorado’s history. It triggered 1,300 landslides, damaged some 19,000 homes and commercial buildings, required the evacuation of more than 18,000 people, damaged 27 state dams (and completely took out a handful of “low-hazard” dams), and damaged or destroyed 50 bridges and 485 miles (780 kilometers) of roads. Losses were estimated to total some $3 billion.²

Floods of this magnitude, while rare overall, are completely unexpected in Colorado in the very late summer. In river systems fed by melting snows, the biggest floods normally occur in the spring, as temperatures warm and snowmelt pours into headwater streams and the rivers they feed. Intense summer thunderstorms occasionally create localized flooding in July or August, but by September rivers are typically running low, just as the Poudre was when I drove up the canyon.

Brad Udall, a water and climate expert at the University of Colorado in Boulder, whose house sits just 30 feet (9 meters) from a creek that’s normally dry in September, saw the creek turn into a raging stream. “This was a totally new type of event,” Udall told National Geographic, “an early- fall, widespread event during one of the driest months of the year.”³

So often these days water seems to be nowhere and everywhere all at once. The wild weather of 2015 became almost legendary, even before the year was over. With raging floods in Latin America, the US Midwest, and the United Kingdom, and withering droughts in eastern and southern Africa, most of California and southeastern Brazil, terms such as anomalous, historic, and epic dominated the weather lexicon. US scientists determined that during one rare October rainstorm 17 streams in the US state of South Carolina broke records for peak flow. According to the United Nations, two years of drought left nearly 1 million African children suffering from acute malnutrition, and millions more at risk from hunger, water shortages, and disease.⁴

Although the weather phenomenon known as El Niño became the go-to explanation for the global turmoil that year, this periodic event was not fully to blame. The El Niño came atop long-term warming trends that are fundamentally altering the movement of water across the planet. The earth was hotter in 2016 than since record keeping began in 1880. The previous record was 2015, which itself had beaten the previous record of 2014 by a considerable margin. For the contiguous United States, 2016 marked the twentieth consecutive year that the annual average temperature was higher than the twentieth-century average.⁵

As air warms, it expands, which allows it to hold more moisture. This, in turn, increases evaporation and precipitation, which generally makes dry areas drier and wet areas wetter. If disasters related to droughts, floods, and other extreme weather seem more common globally, it’s because they are: according to a United Nations study, between 2005 and 2014, an average of 335 weather-related disasters occurred per year, nearly twice the level recorded from 1985 to 1995.⁶

If we don’t adapt to these new circumstances, a future of more turmoil is bound to unfold. The 6,457 floods, storms, droughts, heat waves, and other weather-related events that occurred over the last two decades caused 90 percent of disasters during that period. Those disasters claimed more than 600,000 lives and cost more than $1.9 trillion, according to the UN study. The countries hit with the highest number of disasters over the twenty-year period were the United States, with 472, and China, with 441, followed by India, the Philippines, and Indonesia.

Meanwhile, extreme weather is also affecting our food supply. A team of Canadian and UK scientists found that from 1964 to 2007 droughts and heat waves had each slashed the production of cereals by about 10 percent—and by 20 percent in the more-developed countries. Altogether, the loss was estimated at 3 billion tons.⁷

Leaders in business and government are beginning to take notice. More than 90 percent of companies in the S&P Global 100 Index see extreme weather and climate change impacts as current or future risks to their business.⁸ At its annual gathering in Davos, Switzerland, in 2016, the World Economic Forum—which counts among its members heads of state, chief executive officers, and civic leaders—declared water crises to be the top global risk to society over the next decade. Next on the list were the failure to mitigate and adapt to climate change, extreme weather events, food crises, and profound social instability.⁹ All five threats are intimately connected to water. Guarding against each requires a new understanding of our relationship to freshwater—and a new way of thinking about how we use, manage, and value it.

Water is unlike any other substance. It is always on the move—falling, flowing, swirling, infiltrating, melting, condensing, evaporating—and all the while knitting the vast web of life together. Through its endless circulation, water connects us across space and time to all that has come before and all that is yet to be. Our morning coffee might contain molecules the dinosaurs drank.

This profound connection is created by one of the most mysterious and underappreciated of Earth’s natural phenomena: the water cycle. Those fifth-grade textbook diagrams never quite do it justice. We see the labels of water stocks and flows and the arrows signaling movement from sea to air to land, but never really grasp the magic wrought by two atoms of hydrogen uniquely bonded to one of oxygen. Water is the only substance that can naturally exist as a liquid, gas, or solid at normal Earth temperatures.

With hydrogen from the primordial Big Bang and oxygen from early stardust, water was born. Infant Earth, hot as Hades, was enveloped in water vapor, but it took a billion or more years of cooling before that vapor could condense and fall to the young planet’s surface as rain. Liquid water has wetted Earth for at least three billion years. Today, that stock of water is finite, except perhaps for minute additions from so-called cosmic snowballs—small comets made of water that smash into the earth.

This finite supply circulates over vastly different scales of time and space. Some water molecules get trapped ultradeep within the earth, remain there for millennia, and then suddenly burst into the atmosphere through an erupting volcano. Others reside close to the earth’s surface, changing back and forth between liquid and vapor as they evaporate from a lake, condense into a cloud, and fall as rain to join a river as it flows to the sea. From there, they evaporate again, and the cycle continues. Still other molecules remain trapped for centuries in glacial ice until they melt to replenish a mountain meadow and the groundwater below. “Whenever you eat an apple or drink a glass of wine,” writes astrophysicist and author Robert Kandel, “you are absorbing water that has cycled through the atmosphere thousands of times since you were born. But you are also absorbing some water molecules that have only been out in the open air for a few days or weeks, after tens or hundreds of millions of years beneath the Earth’s crust.”¹⁰

Almost all the water on Earth—97.5 percent—resides in the ocean and is too salty to drink or to irrigate most crops. Of the remainder, about two-thirds is locked up in glaciers and ice caps. Only a tiny share of Earth’s water—less than one one-hundredth of one percent—is both fresh and continuously renewed by the solar-powered global water cycle.

Each year, the sun’s energy lifts nearly 500,000 cubic kilometers (132 quadrillion gallons) of water from the earth’s surface—86 percent from the oceans and 14 percent from the land.¹¹ An equal amount falls back to Earth as rain, sleet, or snow, but, fortunately for us, not in the same proportions. Wind and weather transfer about 9 percent of the vapor lifted from the sea over to the land. This net addition of about 40,000 cubic kilometers combines with the 70,000 lifted from the land and its vegetation each year to create our total annual renewable water supply: 110,000 cubic kilometers (29 quadrillion gallons). The 40,000 cubic kilometers distilled and transferred from the oceans to the land makes its way back to the sea through rivers and shallow groundwater—what hydrologists call “runoff”—completing the global cycle and balancing nature’s water accounts.¹²

That runoff is what we tap to irrigate crops, supply water to our homes and businesses, manufacture all of our material goods, and run turbines to generate electricity. It is also the water supply for all the fish, birds, insects, and wildlife that depend on rivers, streams, and wetlands for their habitats. Although the water cycle delivers that runoff each year, water is not always where we need it when we need it. Nature’s water deliveries are often poorly matched with where people live or farmers find it best to grow crops. Today, for example, China is home to 19 percent of the world’s population, but only 7 percent of global runoff.¹³

Although we speak of a global cycle, water circulates at many scales. Consider, for example, the tomato plant in...