The Next Species: The Future of Evolution in the Aftermath of Man (20 page)

If models of Southwestern responses to climate change are correct, Southwest US deserts should get warmer and drier. With less moisture, crusts may not form, and sandstorms could become much
more common. Cyanobacteria, mosses, and lichens are critical to the formation of crusts, and crusts are as important to the residents as gambling, though they don’t get much appreciation for their valuable services.

As important as the crusts are, Las Vegas owes its life to the water that is brought to the city by the Colorado River. As with the New York City watershed, the water from the Colorado River originates upriver in less developed forest. The Colorado begins its journey from the snowpack in the central Rocky Mountains and travels south 1,450 miles (2,330 kilometers), draining an expansive yet arid area that encompasses parts of seven US and two Mexican states.

The Colorado River is the principal river of the Southwestern United States and northwestern Mexico. Prior to European settlement, the river entered Mexico, where it formed a large delta before emptying into the Gulf of California off Mexican shores. But for much of the past half century, intensive water consumption upriver has stolen the moisture of the last hundred miles of the river, and it no longer makes it to the Gulf except in years of heavy runoff. Although it is the seventh-longest river in the US, its water volume is quite low. And to make matters worse, for the last couple of decades the population growth along this already strained river has been the greatest in the country.

The immediate outlook is dim, and the long-range picture dimmer. Between 85 and 90 percent of the Colorado River’s discharge originates in snowmelt, mostly from the Rocky Mountains of Colorado and Wyoming. Nevada and other Western states like California and Arizona are already struggling with the problem of diminishing snowpack in their own states, and rely on the Colorado River for much-needed water. Climate change will decrease the volume of precipitation in the Southwest while decreasing the snowpack in the Rockies. Water will be released earlier, which means winter and spring may have sufficient moisture but summer and fall will be dry.

The critical part of this equation for Las Vegas and the Colorado River is increasing use by other desert cities, including Phoenix and
Los Angeles. One of the main reasons for building the Hoover Dam in the first place was to bring Colorado River water to Los Angeles and the rest of Southern California, places that never seem to get enough.

Emma Rosi-Marshall, an aquatic ecologist at the Cary Institute of Ecosystem Studies, works with native fish in the Colorado River. The two major dams,
the Hoover Dam near Las Vegas and the Glen Canyon Dam below Lake Powell in Utah, have had major effects on wildlife and fish in the Colorado River, altering their natural ecosystems, drowning their habitat, and changing the temperatures of the waters in which they evolved.

Completed in 1963, the Glen Canyon Dam in northern Arizona is one of the last large dams built in America. To provide pressure for power generation, the Glen Canyon Dam draws water from the cold depths of Lake Powell, making the water flowing out of the dam much colder than it is naturally for most of the year. This change in the temperature has had enormous consequences for aquatic species. Worms, snails, and many native aquatic insects have disappeared. These were
all-important food sources for native fish. The result is the decline of half the native fishes in the Grand Canyon ecosystem.

Rosi-Marshall works with the charismatic and oddly shaped humpback chub, one of the Colorado River’s native fish, a federally endangered species and an important member of the native aquatic environment. Prior to damming, the chub benefited from snowmelt from the Colorado Rockies during spring thaw that would naturally flood the banks of the Colorado River and shape the surrounding wetlands and beaches. With pressure from environmental groups, state water agencies now release water at different times of the year to try to imitate natural runoff. But the benefits of this strategy remain under investigation. It may be that the Glen Canyon and Hoover Dams have
altered the river’s ecosystem beyond the point where regulating the flow of water through the dams is going to achieve anything like the natural flow of water that existed before them.

The biggest problem for the future of the Colorado River and its surrounding environments is that
the river is rapidly losing water, an issue with repercussions for practically every animal and every plant that relies on it, including man. The volume of water in Lake Meade is down to about 40 percent. Las Vegas currently has two major pipes drawing water out of the lake, but the city needs more. Below Lake Meade, the river is drying up. One of the biggest water users is agriculture in Southern California, and UNLV ecologist Smith wonders just how important and productive those farms are. But if you get rid of local agriculture, then you have to go farther away for your food, inevitably putting more CO
₂
in the atmosphere from food transport, and that could result in decreased snowpack in the Rocky Mountains and diminished rains in the Southwest desert, causing water levels to fall even lower. As at the craps tables at the nearby casinos, in the end you just can’t win.

The Las Vegas Valley, which includes the city, has a population of close to two million, about two-thirds of the people in the entire state. Engineers are proposing to tap underground waters of upstate ranchlands with 145 huge wells spread out over 20 percent of Nevada and connected by one thousand miles of pipe. Such a situation occurred about one hundred years ago when Los Angeles went looking for water in the Owens Valley about three hundred miles upstate on the eastern side of the Sierra Nevada mountains. Los Angeles bought up water rights from Owens Valley ranchers who were misled into thinking they were getting some help with building their reservoirs, but Los Angeles built an aqueduct and sent all the water south.

The Owens Valley slowly surrendered its moisture and the farmers and ranchers moved elsewhere. Water diversions for Los Angeles residents left Owens Lake bone-dry by 1920. Then the dust started blowing. By the 1990s, the Owens Lake playa was the largest producer in North America of PM10 atmospheric dust—particulate matter small enough to enter human lungs. The courts forced Los Angeles to put some water back into the lake, though ecologists continue the fight for more changes in water and land use there. According to
Greg Okin, a professor of geography at the University of California, Los Angeles, “Climate models predict that the Southwest should get warmer and drier, and that by 2050 soil moisture could be
lower than the US Dust Bowl Era.”

The Dust Bowl occurred in the Great Plains of Midwestern America in the 1930s. An unusually wet period had encouraged people to settle there, and the existing rains convinced many to begin plowing the grasslands deeply. This destroyed the grasses, which normally trapped soil and moisture during times of drought and high winds. Thus when drought came in the 1930s, there was little grass to hold the topsoil. In 1930 an extended and severe drought caused crops to fail, leaving the plowed fields exposed to wind erosion, which carried the fine soils east.

The “black blizzards,” as the dust storms were called, began blowing, with disastrous consequences. In May 1934 two dust storms removed massive amounts of topsoil from Great Plains farms and carried it all the way to Chicago, dumping 12 million pounds of dust on that city. Two days later the storm reached the East Coast, dumping huge amounts of dust on Boston, New York City, and Washington, DC, reducing visibility to three feet (one meter) in some places. It has been called the worst drought in US recorded history.

Las Vegas is a human phenomenon, an incredibly large futuristic infrastructure that was built almost entirely in the last hundred years. In 1900 there were about thirty settlers in the valley. Today it has two million. If it took only a hundred years to get to where it is now, how many more years—one hundred? two hundred? three hundred?—will it take to get to the point where there is
not enough water for the city to survive, the desert crusts vanish, the dust starts blowing, and the tourists go home?

To get a glimpse of that dusty, thirsty future, all one needs to do is head down the Colorado River to where it ends about fifty miles south of the US border. The water that lies in its bed there is but a
shallow, narrow swamp of salt and pesticide-laced runoff from crop irrigation.

Aldo Leopold, an American ecologist, forester, environmentalist, and author of
A Sand County Almanac
(1949), once described the Colorado River Delta as a “milk and honey wilderness where egrets gathered like a snowstorm, jaguars roamed, and wild melons grew.” Today, the Cucapá Indians eke out a living in an estuary that is filled with weeds, trash, and occasional swamps of unhealthy water.

Or perhaps the real future of Las Vegas might lie on the banks of the Salton Sea in Southern California, about 120 miles north. This area was born when the Colorado River temporarily diverted into the Salton Sea in 1905. For a time, runoff from farms kept the lake level constant if not polluted. Though the largest lake in California, the Salton Sea is also the lowest, and its water is saltier than the Pacific Ocean.

The Salton Sea enjoyed some success as a resort area in the 1950s as resort communities at Salton City, Salton Sea Beach, and Desert Shores on the western shore and Desert Beach, North Shore, and Bombay Beach on the eastern shore got started and looked promising for a while. But very little development followed due to the area’s isolation and lack of local employment opportunities. With no outflow, the lake kept getting more polluted. In the 1970s, most of the buildings constructed along the shoreline were abandoned. The episode “Holiday Hell” from the television series
Life After People
used the Salton Sea as an example of how a resort town like Palm Springs or Las Vegas could decay if there were no humans left to maintain it.

The birds that migrate to the south side of the lake in winter still draw bird watchers, but that is primarily because all the marshlands in the Imperial Valley, where the Salton Sea lies, are taken up by agriculture.
There’s no place else for the birds to go.

The east side of the sea around the former yacht club is mostly old abandoned trailers and assorted ruins that photographers like to visit—to celebrate what once was, or because some find art in old
rusted ruins.

Las Vegas could get there, too. If the water in the soil gets below Dust Bowl levels, the crusts would break down and the sands might pick up and fly with the wind. If the water runs out and the city goes dry, it wouldn’t take long for the golf courses, the fountains, and the swimming pools to lose their appeal. And if the desert gets hotter and dryer, the great migration and construction boom of the last fifty years could take its final bow.

Some future artist might revel in the rusted infrastructure of the famous Sin City, go looking for relics of slot machines in the nearby dump, or collect neon artifacts for some museum. Or he or she might go rummaging through old books or magazines to discover the tale of how Sin City finally succumbed to drought, dust storms, and sky-high electric bills, and the day the last neon light flickered out.

Will man’s own luck last? Nature holds all the cards.

A
S WE’VE SEEN
, our species is not impervious to the harm we are raining down on the planet. If we keep progressing on all destructive tracks—overpopulation, disease, climate change, destruction of the forests, destruction of the soil, exhaustion of our natural resources—one of them will take us out. Or perhaps it will be the combination of all these factors. We’ll go extinct. It’s a natural process. Usually it proceeds a little slower. Two hundred thousand years, our current stay on earth, is a short life for a species. When I visited Hans-Dieter Sues, curator of vertebrate paleontology at the Smithsonian, he asserted, “The average mammal species might survive about one million years. A clam species maybe ten million years.” But, I tell him, UC Berkeley’s Barnosky thinks a mass extinction could come in three hundred years. And Stanford’s Jackson says the next hundred years could be crucial. Sues leans back in his chair and smiles resolutely. “Nothing lasts forever,” he replies.

Extinction in reality is a simple process. It happens when the death rate of a species exceeds the replacement rate by newborns. This will come for man in five hundred, five thousand, or fifty thousand years as current rates of overpopulation, disease, or all the possibilities listed above continue. Toss in a nuclear war, an asteroid (a regular occurrence in our geological history), or a supervolcano (a major factor in the Permian and Cretaceous), and we’re there much faster. One of
these could get us, but a multipronged assault will probably yield a cleaner kill.

The problem is we look around at our advanced culture and see an indomitable force. But that’s an illusion. We’re really more like a virus, about ready to run its course. Said biologist Jim Estes when I visited him at the Long Marine Lab at UC Santa Cruz, “There is no reason to think we will live on in perpetuity when nothing else ever has.”

So what if we were out of the picture, not hanging around the old haunts anymore? What would happen to nature? The extinction of
Homo sapiens
would be the equivalent of a soldier yelling for a cease-fire, and the bullets stop whizzing overhead. Nature would be able to catch its breath and calm down, but full recovery from man’s 200,000-year assault on nature would take some time.

It took the earth about ten million years to
recover from the Permian extinction. It took insects about nine million years to recover from the Cretaceous extinction. Other mass recoveries have been much quicker. How the extinction process might evolve in our current situation is mirrored in earthly catastrophes of the past.

An example of nature’s powers for both destruction and renewal were on display on the morning of May 18, 1980, when the entire north side of Mount St. Helens in the state of Washington collapsed as forces from the interior of the volcano exploded through its cauldron. The blast took the lives of fifty-seven people, including Harry Randall Truman, owner and caretaker of Mount St. Helens Lodge on Spirit Lake at the foot of the mountain. Truman had stubbornly refused to leave his home despite numerous warnings.