Rain

by Cynthia Barnett

  Acidity and alkalinity are measured on what’s known as the pH scale, which runs from 0 to 14. Zero is extremely acidic—battery acid. Fourteen is quite alkaline—liquid drain cleaner. Only distilled water has a neutral pH of 7—this is Professor Sabatini’s most pristine water, ironically, the one we treat the heck out of.

  “Pure” rainwater is already slightly acidic, with a pH around 5.6. Each number represents a tenfold increase, so pH 4 is ten times more acidic than 5, and pH 3 one hundred times more acidic than 5. Most fish cannot survive in waters more acidic than pH 5.

  In the 1960s, American scientists sampling rainfall in the White Mountains of New Hampshire were surprised to find rain with a pH of 4 in the quiet Hubbard Brook Experimental Forest, far from any smokestacks. The ecologists F. Herbert Bormann of Yale and Gene Likens of Cornell went on to test rain throughout the Northeast and found pH levels as low as 2.1. In an article in the journal Science in 1974, Bormann and Likens connected the deaths of forests and fish in the United States, Canada, and Europe, along with many other ecological impacts they could see or suspect, to acid rain dispersed over long distances by burning fossil fuels.

  They sounded the alarm just as Congress was considering loosening the pollution controls of the Clean Air Act of 1970 in response to the era’s energy crisis. Instead, the United States and Europe started down a long road to cleaning up the rain. Regulation—especially a cap-and-trade program that lets coal-burning power plants buy and sell emissions permits—has helped reduce the sulfur dioxide released into the atmosphere by more than half. Twenty-five years ago, 18.9 million tons spewed into U.S. skies annually. Today it’s well under 8.9 million, the government’s cap. In places most prone to acid rain, such as the Ohio River Valley, the pH of rainfall is slowly climbing back from below 4.

  While many people who remember the acid rain crisis think of it as “solved,” scientists who study acidity as it travels through air and ecosystems say it remains a pressing problem—one with far greater implications than they initially imagined. Acid rain so altered the soils in those sensitive parts of the nation that trees remain more vulnerable to freeze, disease, pests, and drought. Foresters believe the weakness has led to extensive die-offs of red spruce trees throughout the eastern United States, and sugar maples in Pennsylvania. Lakes are healing in the Adirondacks, but 132 of them remain acidic. Back at the Hubbard Brook Experimental Forest in New Hampshire, rain has become less acidic over the past forty years, but it’s still ten times more so than natural rain.

  “Yes, we’ve made significant improvements and the situation is much safer than it was one hundred years ago and fifty years ago,” Professor Sabatini told me. “But you cannot look at rain and say it’s pure.” That’s because the rain is always returning pollution back to us. Scientists who track contaminants in the atmosphere find that even as the acid rain picture improves in the United States, rain is spreading more nitrogen pollution, picked up from the likes of fertilizers and livestock operations. There is also the reality that while acid rain declines in North America and Europe, it is on the rise in other parts of the world. In southern China, the stoic Leshan Buddha, chiseled into cliffs in Sichuan province during the eighth century, is slowly corroding. The largest premodern statue in the world, its face is streaked with the gray tears of acid rain. At the turn of the century, China surpassed the United States as the largest emitter of sulfur dioxide, and in 2010, India rose to second place behind China. Pollution controls have helped China begin to reduce its emissions; India’s are accelerating amid rapid economic development, fossil fuel use, and lax regulation.

  The atmosphere and its rain are one global system—everything connected to everything else, sometimes in ways we cannot imagine. As our understanding of climate shifted from superstition to science, we learned how an unusually warm sea-surface temperature far out in the Pacific Ocean, El Niño, can bring torrential rains to California or failures of the Nile floods in Egypt. How a dust storm formed over the Sahara Desert can move over the Atlantic Ocean, reducing the odds of a hurricane slamming into Florida. Now, how humans can change the rain in strange ways. In South Florida, studies have shown the massive drainage in the Kissimmee River basin floodplain led to weaker showers over parts of interior Florida. The less water at the surface, the less evaporated to make rain. At the other extreme, researchers now have evidence that the world’s largest human-made reservoirs may be spurring extreme rains and flooding in regions such as northern Chile.

  Just as Thomas Jefferson suspected, alterations to land and water—clear-cutting a forest, draining a wetland, hoisting a dam, paving a recharge area, large-scale irrigation—all have their bigger-than-butterfly effect on the rain.

  At the regional level, agricultural irrigation may be partly to blame for shifting U.S. rainfall patterns, with less falling on the thirsty High Plains region from the Dakotas south to the Texas Panhandle and heavier rains dousing the Midwest. Dr. Jerad Bales, chief water scientist for the U.S. Geological Survey, explains that as farmers pump groundwater up from the High Plains Aquifer and irrigate their crops, the westerlies scoop up the increased water vapor and carry it along, bringing more rain to the Midwest. “As we change one part of the water budget, we change another,” Bales says. “It’s all linked.”

  Even cities can change the rain. The heat-island effect is the best-known example of urban impacts to weather; the more paved surfaces and fewer trees in a city, the hotter it becomes. Now several satellite studies conclude that cityscapes influence storms, too. Scientists analyzing precipitation data alongside satellite images of urbanization in China’s Pearl River delta found a direct correlation between the rapid growth of cities and a decrease in rainfall. In the United States, a long-term satellite project called the Metropolitan Meteorological Experiment, which analyzes weather patterns over urban areas including Atlanta, Dallas, and St. Louis, found that large cities appear to send rain downwind.

  The combination of heat and structures in a city can force up more convective clouds. Skyscrapers can have all sorts of impacts, says the meteorologist Bob Bornstein, who has studied the urban effects of thunderstorms for forty years. They can block sea breezes, act as barriers that force storms around cities, or even split storms in two, tending to send rain to a city’s edges.

  Now, the warming world has revealed how the emissions we send into the atmosphere—including 36 billion tons of heat-trapping carbon dioxide every year, most from China, followed by the United States—can wreak global climate havoc. A warmer atmosphere and oceans mean more energy aloft that must be dissipated; it finds release in extreme weather. Dry areas get drier, rain falls in torrents rather than gentle downpours. Proof that the strangest rains of all are wrought by humans.

  —

  Before Charles Hoy Fort died, his friends, including the writer Theodore Dreiser, founded the Fortean Society; members included the journalist H. L. Mencken and science fiction writers such as Eric Frank Russell. But Fort himself refused to have anything to do with it. He said he didn’t believe in the supernatural. He just liked to collect weird facts, use them to satirize authority, and complain how nobody was doing anything about the black rains.

  The Forteans endure today, with offshoots around the United States, the United Kingdom, and Australia. A U.K.-based magazine, Fortean Times, is still published monthly. Modern writers who’ve cited Fort’s influence include Robert A. Heinlein and Stephen King. In King’s novel Firestarter, the parents of a child who can start fires telepathically are advised to read Fort’s book Wild Talents instead of Dr. Spock.

  Another fan is the American filmmaker Paul Thomas Anderson. In his 1999 movie Magnolia, Anderson directed one of the most shocking rains of film history when he sent grotesque frogs, big as four-pound broilers, pounding from the sky in a heavy rainstorm. At first, it looks as if just a few plump frogs are being flung past the windows of characters involved in the nine-way plot. Then, as the camera holds a shot of a swimming pool, underwater lights glowing in the nig
ht, the staggering scale is revealed. Thousands upon thousands of oversized frogs hurl down with the hammering rain—plopping into the pool, thwacking deck and diving board, crashing into trees, and thudding into the street until it’s lumpy with carcasses.

  Anderson says Magnolia’s amphibian apocalypse was inspired by Fort, whose writing on frogs then sent him to read Exodus. Magnolia is full of Fortean cameos; the child genius in the film reads Wild Talents as he sits in a library cramming to prepare for his appearance on a TV game show. Charles Fort “believed in ‘Megonia,’ a mythical place above the firmament where stuff would go up to and hang out before dropping back down to Earth. Magnolia is a little tribute to that,” Anderson told Variety. “And it sounds funny, but he believed that you can judge a society by the health of its frogs. That doesn’t seem too crazy to me.”

  It doesn’t seem too crazy at all. Scientists say frogs are bioindicators; their well-being reflects the environment’s. Because they require both land and aquatic habitat, and have permeable skin that easily absorbs toxins, they are faithful signals of ecological havoc.

  There is no greater rain lover than the frog. This truth is held so deeply in India that, when drought takes hold and people are desperate for rain, they’ll search out a pair of frogs and organize a frog marriage, replicating all the customs and rituals of a human wedding with hundreds of guests. After the nuptials, the frogs are set free with a prayer for rain.

  Frogs symbolize rain for many Native American tribes. Among the Zuni who live beside the Zuni River in New Mexico, frogs are considered the children of six rain priests—U’wanami—who live in houses made of cumulus clouds. The Hopi fashion musical instruments from gourds, a resonator and rasping stick, that mimic the song of frogs to call home rain.

  Frogs do seem to call the rain, or at least predict it. Nineteenth-century science journals describe how Europeans kept tree frogs in tall glass jars as wee weather forecasters. Frogs have a “barometric propensity,” wrote one chronicler, crawling up their tiny ladders on sunny days, hunkering down in the water below when a storm approached.

  In Louisiana, the Creole people say: Laplie tombé ouaouaron chanté—“when the rain is coming, the bullfrogs sing.” In my home state of Florida, summer storms are preceded by an ecstatic, escalating ensemble. The weatherwise chorus includes the rain call of the squirrel tree frog—a chattering scold that sounds just like its namesake—and that of the green tree frog, whose rain call southerners claim sounds like “fried bacon, fried bacon.”

  Many people in the South just call any tree frog a rain frog. As soon as the rain arrives, the mass chorus changes on cue, from rain call to mating call. Frogs often wait for a “stump-floating storm” to breed, explained the late Florida naturalist Archie Carr. Those that lay their eggs in a new rain pool protect their young from the enemies lurking in established ponds, carnivorous water bugs and beetles.

  If Fort is right that society shall be judged by the health of its frogs, we’re in for a harsh adjudication. Frogs have survived in more or less their current form for the past 250 million years—they made it through the mega-droughts and the pluvials, the ice ages and the asteroids. Today they are vanishing; perhaps this is why frog rains have become so rare in modern times. Nearly two hundred frog species have vanished since 1980 and more than a third of all surviving amphibians are now threatened with extinction, part of a larger catastrophe that scientists call the world’s sixth mass extinction.

  The rain-loving little bioindicators are definitely trying to tell us something.

  THIRTEEN

  AND THE FORECAST CALLS FOR CHANGE

  On Memorial Day weekend in 2013, Dave Tzilkowski and his wife, Jillane Hixson, saw dark and massive storm clouds rumbling toward their house in Lamar, Colorado. As they hunkered down, the storm pounded the windows with what sounded like hail, and beat against the door with sixty-mile-an-hour winds. They were trapped inside for fifteen hours.

  Tzilkowski and Hixson had been praying for rain, but this storm brought none. It carried a towering wall of dust, as if blowing from the Dirty Thirties. Similar dust storms have rumbled along the flat landscape of southeastern Colorado since 2011, one of the devastating strikes of a drought that climate scientists say is more extreme in this part of the plains than the Dust Bowl that bore down here seventy-five years ago. The past three years have been the driest in recorded history. The tumbleweeds have to be pushed out by snowplow.

  The drought and the dust storms have desiccated the wheat crops and the native grasses, too. Prairie normally covered with thousands of acres of cultivated wheat is bare and burnt brown. Farmers’ losses are in the millions. Ranchers have sent thousands of head of cattle away to other states. They hope they will not have to relocate their families next.

  The same year the Memorial Day duster hit southeast Colorado, in September, copious rains surprised the Front Range on the north side of the state. Residents described the downpours as biblical—or like hell. The storms began on Monday the 9th and did not stop for eight days. Soothing creeks turned to seething rivers. In business districts and neighborhoods, muddy brown floodwaters rose waist-deep. Roads gave way and took cars with them, including a little Subaru carrying four teenagers home from a birthday party in the craggy hills outside Boulder. Floodwaters and mud swept away sweethearts Wesley Quinlan and Wiyanna Nelson, among eight residents who died in the storm. In the largest airlift since Hurricane Katrina, more than a thousand people had to be evacuated from the streaming hills, including an elementary school full of children.

  Like the southeastern Colorado drought, the northern Colorado rains broke many previous records, with 9.08 inches falling in twenty-four hours at the peak of the storm. The Boulder area broke every rainfall record on its books—heaviest rain in a day, in a month, and ultimately, in a year. (Not only did the southeastern drought continue after the heavy rains in the north, but more dust storms, strong enough to shut down the highways, rolled in just days later.)

  In Colorado, drought and flash floods are nothing new. In July 1976 the Big Thomson Canyon Flood killed 145 people, many of whom were enjoying summer holidays at a popular camping spot an hour northwest of Denver. A thunderstorm lifting over the Front Range stalled and dumped a foot of rain in the canyon in three hours, turning a placid stream into a nineteen-foot wall of raging water.

  The 2013 floods, which even the National Weather Service described as out of Scripture, had their meteorological explanation, too. A stationary low-pressure system over the Front Range pulled from two converging plumes of wet weather: a healthy monsoon sweeping out of the southwest from the Pacific Ocean, and a moist tropical system moving north from the Gulf of Mexico. But the question on everyone’s minds—from the many atmospheric and climate scientists who live in Boulder, home to the National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration (NOAA), and the University of Colorado, to the thousands of home owners with destroyed houses and no flood insurance—was whether human-caused climate change had made the rains worse.

  Scientists can’t tie the tragedy of any particular deluge or drought to human-caused climate change, the warming of Earth’s average temperature by heat-trapping gasses. We’ve seen the extent to which our settlement patterns worsen the impacts of natural disasters regardless of what we’ve done to the atmosphere. But scientists detect the force of climate change in an increasing number of extreme weather events. Human-driven climate change is now impacting all weather, says Martin Hoerling, a climate scientist in NOAA’s Earth System Research Laboratory in Boulder. “Rainfall and other weather events happening today are happening in a different climate than one hundred years ago, and so they are behaving differently than they would have a hundred years ago,” he says. “The question is how much.”

  While rain is one of the trickier parts of the atmosphere to measure and to understand, changing rainfall patterns are among the earliest and most obvious tremors of a warming globe. The warmer Earth becomes, the greater t
he amount of water vapor that forms in the atmosphere. Higher temperatures cause greater evaporation—and therefore more rain—where water exists. They make it hotter and drier where water is scarce. The Intergovernmental Panel on Climate Change stresses that extreme rain events are already increasing in North America and Europe. The scientists predict greater intensity and frequency of both drought and extreme rains around the world as it continues to warm, droughts worsening in arid regions while wet areas become wetter.

  The questions of just how much more water vapor will fill the atmosphere in the future—and what the consequences will be—are both unsettled and unsettling. Remember from the early days of Earth that water vapor is a strong greenhouse gas, more potent than carbon dioxide or any other. Water vapor’s natural warming has helped keep Earth in the “Goldilocks spot” that gives us our ideal atmosphere. As the world consumes ever more fossil fuels and temperatures continue to rise, scientists say that the increase of water vapor in the atmosphere could double the greenhouse effect caused by carbon dioxide alone. Some of them, including James Hansen, retired head of NASA’s Goddard Institute for Space Studies, believe the hike in water vapor could ultimately cause a “runaway greenhouse.” We heard this term used to describe what happened to the rains and oceans of Venus. Remember how our Evening Star was born with water, just like Earth? At some point, Venus was caught in a runaway greenhouse. Its oceans essentially boiled away.

  Other climate scientists are wary of the apocalyptic notion, and Hansen acknowledges that it won’t happen soon enough for our grandchildren to see it. But they will be around for the storms, evoked in Hansen’s 2009 book Storms of My Grandchildren. In the years 2011 and 2012, although many parts of the world saw record-breaking heat and drought, the continents collectively drew their two heaviest years of cumulative precipitation since modern record-keeping began.