Rain: A Natural and Cultural History

Cynthia Barnett is a finalist for the PEN/E.O. Wilson Literary Science Writing Award for Rain: A Natural and Cultural History. Her book traces the history of rain from the drops that filled the oceans to the present storms of climate change. Blending scientific analysis with thoughtful discussion of rain’s role in culture, Barnett tells the story of rain’s effect on humans, and now, humans’ effect on rain. The following is an excerpt from the book.

Prologue
ORIGINS

The rain on Mars was gentle, and welcome. Sometimes, the rain on Mars was blue. One night, rain fell so marvelously upon the fourth planet from the sun that thousands of trees sprouted and grew overnight, breathing oxygen into the air.

When Ray Bradbury gave Mars rain and a livable atmosphere in The Martian Chronicles, science fiction purists grumbled that it was completely implausible. In the previous century, astronomers—and writers like H. G. Wells who borrowed from their work to give sci-fi a tantalizing authenticity—had seen Mars as Earthlike, odds-on favorite for life on a planet other than our own. But by the time The Martian Chronicles was published in 1950, those odds had changed. Scientists viewed Mars as chokingly dry, impossibly harsh—and far too cold for rain.

Bradbury didn’t care to conform to the scientific views of the day. On any planet, he was much more interested in the human story. He created a rain-soaked Venus, too, but not because scientists then considered it a galactic swamp. Bradbury just loved rain. It fit his melancholy like a favorite wool sweater. As a boy, he had loved the summer rains of Illinois, and those that fell during family vacations in Wisconsin. Hawking newspapers on a Los Angeles street corner as a teen, Bradbury never minded a late-afternoon deluge. And in his eighty years of writing every day, raindrops tap-tap-tapped from the typewriter keys into many a short story and every book. A Bradbury rain could set a gentle scene or a creepy one. It could create moods of gloom, mania, or joy. In his short story “The Long Rain,” he made rain a character all its own: “It was a hard rain, a perpetual rain, a sweating and steaming rain; it was a mizzle, a downpour, a fountain, a whipping at the eyes, an undertow at the ankles; it was a rain to drown all rains and the memory of rains.”

So often making rain the mise-en-scène for life, Bradbury was onto something. Everyone knows that life could not have developed without water. Life as we define it required a wet and watery planet. But the Earth-as-exceptional-blue-marble story many of us grew up with is, in some ways, as much a product of the human imagination as the warm Mars sea of The Martian Chronicles. Modern scientists have good evidence that Earth did not develop as the sole wet and watery orb in our solar system. Earth, Mars, and Venus were born of the same batch of flying fireballs. All three boasted the same remarkable feature: water.

What’s exceptional about our blue marble is not that we had water. It’s that we held on to it, and that we still do. While the ancient oceans of Venus and Mars vaporized into space, Earth kept its life-giving water.

Luckily for us, the forecast called for rain.

***

As even-tempered as it grew up to be, Earth started off 4.6 billion years ago as a red-faced and hellish infant. The universe had been unfolding for about 10 billion years. A new star, the sun, had just been born. Its afterbirth—cold gas and dust and heavier minerals and flaming rocks—was flying about, beginning to orbit. The heavy debris gravitated to the sun, where temperatures were well suited for rock and metal to condense. That’s why the four planets closest in, known as the terrestrials, are all made of essentially the same stuff.

For its first half-billion years, Earth was a molten inferno some 8,000 degrees Celsius—hotter than today’s sun. Scientists call this violent era the Hadean, from the Greek word Hades, or hell. Time and again, the young Earth built up a crust, only to see it incinerated by storms of flaming meteors.

Inside the fiery storms, though, was a lining better than silver. Virtually all of the rocks that made Earth had water locked inside. Water is a remarkable shape-shifter, able to change from liquid to solid—or to gas when it needs to make an escape. As meteorites crashed onto Hadean Earth and split apart, they spewed out water in the form of vapor. This was water in its gas form, no different from the steam rising from a boiling pot on the stove. In a sort of geologic burping contest, both the crashing boulders and young Earth’s rising volcanoes disgorged water vapor and other gases into the Hadean atmosphere.

All that water vapor would prove an invisible redeemer. Today, at any moment, more water rushes through the atmosphere than flows through all the world’s rivers combined. The molecules speed around like pinballs, bouncing off one another, off other types of molecules, off dust and salt from sea spray. Only when air cools do they slow and begin to stick together, latching on to the gritty particles. When billions of them have condensed, they form tiny liquid droplets. Billions of the droplets, in turn, become clouds in the sky. This is the beauty of water vapor: It falls back to Earth as rain.

When Earth was still a molten mass and hot as Hades, the vapor could not condense. Instead, it hissed away into space. Eventually, though, it began to build up in the young planet’s atmosphere. Water vapor is a heat-trapping, or greenhouse, gas just like carbon dioxide. The more gas that built up, the hotter and hotter Earth became—melting the forming crust all over again as the flaming boulders continued to fall like bombs from outer space.

About half a billion years after it started, the blitzkrieg began to wind down. As the last of the flaming chunks fell to the surface or hurtled away, the planet finally had a chance to cool. The water vapor could condense.

At long last, it began to rain.

***

In 1820, John Keats lamented in his narrative poem Lamia how little science leaves to the imagination. The scientist’s cold philosophy and dull catalog, the English poet wrote, might as well “unweave a rainbow.” The mystery of the rainbow—viewed by many throughout the world as a passageway between heaven and Earth—was dashed, Keats charged, when Isaac Newton explained the optical truth: Rainbows are the refraction of sunlight through raindrops.

Yet Newton was anything but unimaginative. To conceive of gravity, he had to imagine Earth pulling an apple from a tree, pulling the very moon into our orbit. It takes such an eye to picture Earth’s first rains—the greatest storms of all time. So much of the young planet was destroyed during the Hadean that scientists have scant physical evidence to suggest exactly when the earliest rains began, what they looked like, and how long they poured.

The best clues to the first rains lie in Western Australia’s Jack Hills. Deep in the craggy orange sandstone there, geologists have dug up tiny grains of zircon that clock in as the oldest terrestrial material found on Earth to date. Nature’s trustiest timepiece—the radioactive element uranium—dates the tiny zircons back 4.2 billion years. By then, their chemistry suggests, primeval rains had begun to fall and pool on the Earth’s crust. Those earliest lagoons likely boiled away repeatedly in the Hadean’s grand finale, called the Late Heavy Meteorite Bombardment, which also cratered our moon.

Only when the meteor storms let up could the great rains let loose. By this time, scientists infer, baby Earth was swaddled in vaporous clouds. So many volatiles had built up in the atmosphere, they moiled the sky thicker than a Newfoundland sea fog, blacker than a line of tornadoes on the Great Plains.

Still, Earth’s charred surface likely remained so hot that the rains fell only partway to the ground, evaporating again and again. The Stygian clouds grew impossibly heavy. Lightning, its charges tied to the amount of water in the air, illuminated the lonely scene.

The water vapor accumulated in the upper atmosphere for so long that when the surface finally cooled enough for the rains to touch down, they poured in catastrophic torrents for thousands of years. This was the picture the Stanford University geochemistry professor Donald Lowe painted for me when I asked him to imagine Earth’s first rains. Lowe is known for his research on the surface of early Earth and the deepest sediments of today’s oceans. He grew up in rain-starved California and lives there now, but he spent half his career at Louisiana State University in Baton Rouge, one of the rainiest cities in the United States. And so it is no surprise that he imagines the first rains like the gullywashers of southern Louisiana, so dense that motorists ease over to the side of the road to wait out the deluges that rap on their car roofs like a steel band’s drumroll.

***

In Ray Bradbury’s 1950 story “The Long Rain,” later featured in the film The Illustrated Man starring Rod Steiger, four Earthmen crash their rocket ship on a Venus drowning in such torrents. The spacemen trek through the sopping Venusian jungle in search of warm, dry shelters known as Sun Domes. They have no gear, not even hats to keep the streaming rain from pounding their heads and seeping into their ears, eyes, noses, and mouths. They have no shelter, for their rocket ship has been contaminated, and Venus’s swampy undergrowth drips as much as its skies. As they search for the cozy Sun Domes, the rain drives each man mad.

With his aqueous Venus, Bradbury, this time to the satisfaction of the planetary purists, reflected the common scientific beliefs of the day. The irony is that in the 1960s, real spaceships discovered that Venus was dry as dust. Conventional wisdom swung from the early view that Venus was waterlogged to the hypothesis that it was always parched.

Today, the evidence has most planetary PhDs convinced that Venus once had what Earth had—water vapor condensing to epic rains that turned much of the surface to liquid—but somehow lost it. Mars, too, appears to have begun life with a warm, wet climate, a huge ocean of water covering nearly a third of its sphere, river valleys carved by rainfall, deltas as expansive as the Amazon’s.

Like many planetary scientists, David Grinspoon, chair of astrobiology at the Library of Congress, was drawn to the field by the science fiction writers of his boyhood, including Bradbury and Isaac Asimov, whose book Lucky Starr and the Oceans of Venus first piqued his interest in the lost Venusian seas. Earth, Mars, and Venus “started out wet,” Grinspoon explains, “drenched by the same scattershot rain of planet pieces.” Grinspoon is a musician in a funk band called House Band of the Universe. In the case of Mars and Venus, the question is a twist on the old Creedence Clearwater Revival song: What stopped the rain?

Venus, closer to the sun, appears to have become too hot, its oceans vaporizing away. The searing heat kept the vapor from condensing and completing the circle as rain. Remember that water vapor is a greenhouse gas—more potent than carbon dioxide or any other. The more that built up in the Venusian atmosphere with no rain, the hotter the planet became. This cycle, known as a runaway greenhouse effect, usurped the water cycle. Venus cooked.

Mars, on the other hand, became too cold. Scientists believe the red planet was once wrapped in a thick atmosphere that kept it warm enough for bountiful water. From today’s dry and dusty Mars, NASA’s orbiters and rovers beam home evidence of rain-carved channels, branching rivers, deltas that might have carried ten thousand times the flow of the Mississippi River. Over perhaps hundreds of millions of years, the cozy Martian air turned cold and thin. The rains dried up. The flowing waters vanished.

Water still exists on Mars—frozen in its polar ice caps and rocks, hidden deep below ground, and in a touch of water vapor in the atmosphere. But whatever frigid hydrologic cycle that remains is not driven by rain.

While Venus grew too hot and Mars too cold, Earth kept just the right atmosphere to hold its water in balance—to hold the rains that turned our fiery young planet blue. Those first rains cooled the hell-charred Earth. They filled its craters and crevices until the ground could absorb no more. They spilled across the meteorite-ravaged terrain, cutting channels that became Earth’s first rivers. The rains became the land’s first lakes. The lakes spread across the steaming landscape like pools in a rising tide. Over years and decades and centuries, the liberated rains filled great basins and became oceans. Over still more time, they seeped down below the land and sea, filling aquifers that now hold far more freshwater than all our lakes and rivers combined.

Somewhere, sometime, the first rains helped lead to the first life. Whether those primordial cells were stirred up in Charles Darwin’s “warm little pond” or originated in hydrothermal vents deep in the seafloor as many scientists today hypothesize, the first life required the rain.

Water alone is not enough, Grinspoon explains. Water is “out there,” too—in the atmosphere of Venus and in the polar caps of Mars—but it does not sustain a living world on either of those planets. To become our life force, water also had to build up in the skies, move along with the wind, and pour back to the surface, replenishing the waters, lands, and beings again and again.

***

From those cataclysmic torrents 4 billion years ago to the hydrologic cycle that slakes aquifers, soil, and rivers day after day, rain, as the source of Earth’s water, became the wellspring of life. “Sunshine abounds everywhere,” the American nature writer John Burroughs wrote in a paean that soaked nine pages of Scribner’s magazine in 1878, “but only where the rain or dew follows is there life.”

Life, and something more. Humans have a natural affinity for rain, grounded in its necessity for civilization and agriculture. Thomas Jefferson constantly watched the sky from his Monticello home in Virginia, where cerulean thunderclouds build along the Blue Ridge Mountains as if matched by Picasso. Jefferson fretted over cloudless days the way that all farmers do. He found relief when storms returned, carrying moisture from the yet-mysterious West. His letters often closed with a word on the rain—or the lack. “Not enough rain to lay the dust,” he would lament. Or he’d gratefully share news of “a fine rain,” “a divine rain,” “plentiful showers.”

Sometimes, after writing to his fellow statesman James Madison, who measured rain in a tin cup nailed to the front gate at his Montpelier estate thirty miles northeast, Jefferson would hold off sealing the letter until morning so he could report the overnight showers at Monticello. “The earth has enough,” Jefferson concluded after one such update, “but more is wanting for the springs and streams.”

Wanting is apropos, a hint at something more. For the story of rain is also a love story—the tale of “certain unquenchable exaltation” that the poet William Carlos Williams felt as he beheld his storied red wheelbarrow

glazed with rain
water.

And for all of history, it has inspired all the excitement, longing, and heartbreak that a good love story entails. The first civilizations rose and fell with the rain, which has helped shape humanity since our earliest ancestors radiated out of Africa when the rainfall tapered off and the forests turned to savanna grasslands. Every culture had its own way of worshipping rain, from Mesoamerican cave paintings exalting rain deities to modern Christian governors who call prayer for a storm.

Rain and two more of its wondrous pride—clouds and rainbows—have inspired writers, painters, and poets for thousands of years. Homer’s Iliad is thick with clouds, as is much of the ancients’ poetry and prose. The modern poets wrote unforgettably of rain—what Conrad Aiken called the “syllables of water.” Other authors awakened in its absence: Mary Austin, Willa Cather, and Wallace Stegner all found their muse in thirsting lands. True, the sun and the wind inspire. But rain has an edge. Who, after all, dreams of dancing in dust? Or kissing in the bright sun?

***

We long for rain especially when we’ve gone without. Rain is bliss when topsoil has turned to dust; when springs have vanished; when frogs have gone silent; when fish have rotted to eye socket on dry lake; when corn has blackened on the stalk; when fat cattle have shriveled to bone; when half a billion Texas trees have perished; when bushfires have incinerated Australia; when unthinkable famine has spread through North Africa.

And then, fast as hundred-mile-per-hour winds, a celebration of rain can turn to terror and the deepest grief. Consider the stormy evening of January 31, 1953, in the Netherlands. Dutch families in the coastal provinces of Zeeland and South Holland had gone to sleep in a festive mood. It was Princess Beatrix’s fifteenth birthday. Rain, wind, and waves drum-rolling into the jetties had amplified spirits.

By 2 a.m., the apocalyptic North Sea Storm was pushing floodwaters over dikes and wooden barriers “like boiling milk.” When it was over, when all the lost souls were finally counted, they numbered 1,835. Half a century later, another biblical flood, Hurricane Katrina in New Orleans, took 1,836.

Rain itself is seldom the deadly factor in a tempest; wind is often the most destructive force in storm disasters. But the North Sea Storm and Hurricane Katrina, like most every flood disaster in history, spun off an eternal human response: People viewed the flooding like an attack of nature, and vowed to fight back. Like every culture before or since, they convinced themselves that humans could ultimately master the rain.

Ancient Rome had its rain god, Jupiter Pluvius. During drought-induced famine, Aztecs sacrificed some of their very young children to the rain god Tlaloc. In Europe during medieval times, when the extreme rains of the Little Ice Age led to crop failures, starvation, cannibalism, and other horrors, religious and secular courts stepped up hunts, trials, and executions of witches, accused of conjuring storms.

America’s natives spun in rain dances with tiny bells attached to belts and walking sticks. Their jingling was soft compared with the cannon blasts of the late 1800s, when some settlers were convinced that firing cannonballs, setting enormous fires, or cutting tracts of forest would yield rain. These and other foolhardy schemes helped lure thousands of naïve homesteaders to try to farm some of the driest land in the new nation.

Quackery ultimately gave way to science and birthed the field of cloud-seeding, a chemical milking of clouds. Today, seeding projects continue in the American West and many other parts of the world. The largest efforts take place in China, where government scientists say they coax showers in arid regions by firing silver iodide rockets into the sky.

If cloud-seeding were a real solution, of course, China’s Yangtze River would not be drying up, along with nearby lakes, reservoirs, crops, and livelihoods. Parts of the United States would not be in the grip of the most severe drought since the Dust Bowl—Colorado River drying, California’s reservoirs dropping, lush croplands turned to dust.

Even as much of the nation suffers drought, other parts endure increasingly extreme rains, and ominous superstorms such as Hurricane Sandy, the largest Atlantic hurricane on record when it slammed into the Eastern Seaboard in October 2012. Yet we carry the presumption of Jupiter Pluvius, strong enough to erect colossal storm barriers to push unwanted floodwater away in times of too much, clever enough to design enormous reservoirs to store precious rainfall in times of too little. It will turn out that humanity did, in fact, manage to alter the rain.

Just not in the ways we intended.

***

Wrapping our bodies in Gore-Tex and our cities in giant storm gutters, humans crave mastery over the rain. Yet even in the age of precipitation-measuring satellites, Doppler radar, and twenty-four-hour weather streamed to our smartphones, rain does not give up its mysteries. Hundreds of tiny frogs or fish sometimes fall in a rainstorm, as they have since the beginning of recorded history. Despite forecasting supercomputers that crunch more than a million weather-data observations from around the world each day, rain can still surprise the meteorologist and catch the otherwise elegant bride cursing on her wedding day.

We misunderstand the rain at the most basic level—what it looks like. We imagine that a raindrop falls in the same shape as a drop of water hanging from the faucet, with a pointed top and a fat, rounded bottom. That picture is upside down. In fact, raindrops fall from the clouds in the shape of tiny parachutes, their tops rounded because of air pressure from below.

Our largest and most complex human systems often have the rain wrong, too. In the wettest parts of the United States, we construct homes and businesses in floodplains, then lament our misfortune when the floods arrive. In the driest regions, we whisk scant rainfall away from cities desperate for freshwater. Amid the worst drought in California history, the enormous concrete storm gutters of Los Angeles still shunt an estimated 520,000 acre-feet of rainfall to the Pacific Ocean each year—enough to supply water to half a million families.

These paradoxes could not be more urgent today, as we figure out how to adapt to the aberrant rainfall and storm patterns, increasingly severe flooding, and more-extreme droughts wrought by climate change. Globally, the continents recently drew the two heaviest years of rainfall since record-keeping began. Scientists are bewildered by the controversy over whether human-caused greenhouse gas emissions are to blame for the precipitation extremes. Increased greenhouse gases push temperatures higher. Higher temperatures cause greater evaporation—and therefore greater rainfall—where water exists. They make it hotter and drier where it does not.

Climate change frightens and divides us, to such an extent that many people simply refuse to talk about it all. But everyone loves to talk about the rain. Too much and not enough, rain is a conversation we share. It is an opening to connect—in ways as profound as prayer and art, practical as economics, or casual as an exchange between strangers on a stormy day. Rain brings us together in one of the last untamed encounters with nature that we experience routinely, able to turn the suburbs and even the city wild. Huddled with our fellow humans under construction scaffolding to escape a deluge, we are bound in the memory and mystery of exhilarating, confounding, life-giving rain.

Rain: A Natural and Cultural History

Read more from the finalists of the PEN/E.O. Wilson Literary Science Writing Award