Large Droughts Coming - Water Shortages

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Large Droughts Coming - Water Shortages

Post by  on Thu May 31, 2012 9:19 am

A Drier and Hotter Future

By Donald Worster

A GREAT ARIDNESS: Climate Change and the Future of the American Southwest. William deBuys. xii + 369 pp. Oxford University Press, 2011.




While I was reading William deBuys’s new book, A Great Aridness,
two massive dust storms reminiscent of the 1930s raged across the skies
of Phoenix and of Lubbock, Texas. Newspapers blamed them on the current
drought in the West, which is proximately true. But what ultimately is
causing this drought, and why would any drought produce such terrifying
clouds of dust? The answer is that they may be portents of a more
threatening world that we humans are unwittingly creating. As deBuys
explains, “Because arid lands tend to be underdressed in terms of
vegetation, they are naturally dusty. Humans make them dustier.”

Agriculture is the main reason for those dust storms—the clearing of
native grasslands or sagebrush to grow cotton or wheat, which die
quickly when drought occurs and leave the soil unprotected. Phoenix and
Lubbock are both caught in severe drought, and it is going to get much
worse. We may see many such storms in the decades ahead, along with
species extinctions, radical disturbance of ecosystems, and intensified
social conflict over land and water. Welcome to the Anthropocene, the
epoch when humans have become a major geological and climatic force.

DeBuys is an acclaimed historian turned conservationist in his adopted home of the Southwest. A Great Aridness
is his most disturbing book, a jeremiad that ought to be required
reading for politicians, economists, real-estate developers and anyone
thinking about migrating to the Sunbelt. In the early chapters he
reports on the science of how and why precipitation and ecology are
changing, not predictably but in nonlinear ways that make the future
very uncertain and dark. In later chapters he visits ancient pueblo
ruins left behind by earlier civilizations that were destroyed by
drought, and he follows the grim trail of migrants crossing the border
from Mexico, stirring up a controversy that climate change can only
exacerbate. The book is an eclectic mix of personal experience,
scientific analysis and environmental history.

Smoke as well as dust is spoiling the southwestern skies. As deBuys
points out, forest fires are getting much bigger. In June 2002 the Rodeo
and Chediski fires erupted on Arizona’s Mogollon Plateau, soon merging
into a single conflagration that consumed nearly 500,000 acres. It was
Arizona’s largest fire—until the Wallow Fire eclipsed it in June 2011.
Another devastating effect of climate change has been the explosion of
bark beetles among western pines, which in turn contributes to the new
fire regime; in 2003, dead trees covered 2.6 million acres in Arizona
and New Mexico. Could anything be more demoralizing than the sight of
green forests turned a grisly brown, then bursting into flame and left
charred and black?

Even more depressing than declining forests are mountains bare of
snow. When future springs arrive, the sound of running water will be
much diminished. The biggest environmental catastrophe for the
Southwest, already our most arid region, is losing the melting runoff
from snowpacks into rivers, canals and irrigation ditches. An ominous
chapter in the book examines the future of the Colorado River, which for
decades has been the “blood” of the Southwest’s oasis civilization. In
the 1920s Americans divided the river between upper and lower basins,
allocating to each a share of the annual flow. California, which
contributes almost nothing to the river, sucks up the largest share of
any state, spreading it across the Imperial Valley’s agricultural fields
and diverting the rest to Los Angeles. Years ago policy makers assumed
that the river carried about 17 million acre-feet of water per year—that
is, enough water to cover 17 million acres to a depth of one foot. They
overestimated, as people tend to do when hope and greed outrun the
facts. Now comes a drier and hotter future, when the Colorado River will
carry even less water—perhaps as little as 11 million acre-feet.

Tim Barnett and David Pierce of the Scripps Institution of
Oceanography estimate that to adjust to a sustainable level of supply,
consumers of Colorado River water will have to get along with 20 percent
less water than they use today. That is still a lot of water to lose,
but the loss may not be catastrophic. Urban users are already conserving
about as much as they can per capita. Farmers, on the other hand, who
consume about 80 percent of the western water supply, including in
California, are wasting much through inefficient management and
low-value crops. Half of the water goes to raise alfalfa to feed cattle,
and much of the rest evaporates or soaks into the sand. If some of
agriculture’s share could be diverted to cities, there might be enough
to sustain the current population. Rural communities would decline, some
lucky farmers would retire with a potful of money, and the public would
have to figure out where to get its lettuce, tomatoes, oranges and
meat. The cost of water would go up dramatically, and those without
money would go thirsty and leave. New hierarchies would take the place
of old ones.

Thirty million people now depend on the Colorado River. Perhaps they
can manage to adjust to a diminished flow and to declines in domestic
food supplies and hydroelectric power. But more people are on the way:
Demographers calculate that the population of the Southwest may increase
by 10 or 20 million between now and 2050. Some of those people will
come from other parts of the country, some from Mexico and Central
America, and some from other nations that are coping poorly with their
current problems or are overwhelmed by climate change. Whatever their
origin, the new arrivals will go to the familiar oases, hoping to find
the good life with a swimming pool and a green lawn.

Developers are eager to make money by selling homes to these
newcomers. The political and economic culture of the Southwest is dead
set against any acknowledgment of limits to growth. In the last few
chapters of the book, deBuys shows that even now those in power refuse
to accept any check to expansion; business must be free to do business.
Others say that they are helpless to stop the influx: Patricia Mulroy,
general manager of the Southern Nevada Water Authority in Las Vegas,
declares, “You can’t take a community as thriving as this one and put a
stop sign out there. The train will run right over you.” Her solution is
to create an expensive “straw” to extract water from a shrinking Lake
Mead, drawing on the “dead pool” that will be left below the intakes for
generating electricity. She doesn’t have the money to build that straw
right now, but she is working hard to keep her improbable city from
drying up and becoming a casualty like ancient Mesopotamia. Similarly,
Phoenix continues to issue building permits helter-skelter and counts on
“augmenting the supply” of water sometime in the future. But where will
the state and city go for more supply, and how will they bring it
cheaply over mountains and plains to keep Phoenix sprawling into the
sunset?

DeBuys gathers enough scientific evidence to make a convincing case
against that growth mentality. A similar case could be made against
growth in the rest of the United States, although in the East the threat
may be too much water, not too little, and too many storms, not too
much smoke and dust. The past warns us that ancient peoples once failed
to adapt and survive. Will theirs be America’s fate? Perhaps. But past
human behavior may not be a reliable indicator of how people will behave
in the future. If the environment is becoming nonlinear and
unpredictable, as deBuys argues, then human cultures may also become
nonlinear and unpredictable. No other people have had as much scientific
knowledge to illuminate their condition. What we will do with that
knowledge is the biggest imponderable of all.

Donald Worster is the Hall Distinguished Professor of American
History at the University of Kansas. His current research focuses on the
shift in America from a culture of abundance to one of scarcity. He is
the author of a number of books, including
Rivers of Empire: Water, Aridity, and the Growth of the American West (Pantheon Books, 1985) and The Wealth of Nature: Environmental History and the Ecological Imagination


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