Commentt World water woes
L
ake Lanier, the sole source of drinking water for 3 million people in Atlanta’s metropolitan area, has only a few months’ water remaining if record drought continues. Australia is in the midst of the “Big Dry”, the most severe drought in 100 years. Many farmers in New South Wales experienced record-breaking conditions in September and October and complete failure of the winter crop. Meanwhile, Chile is calling on its mining companies to curtail their massive consumption of process water from streams and wetlands and to begin desalinating brackish water. And the Ganges, the most sacred river in India, which is fed by ancient Himalayan glaciers, is predicted to disappear as early as 2030, according to the UN Intergovernmental Panel on Climate Change (2007). The Ganges Delta is home to 400 million people in India and Bangladesh, more than any other river basin in the world. What do all these problems have in common? Seemingly little, except for the possibility that global warming and shifting patterns of precipitation contribute in some way. Otherwise, each is a separate regional-to-continental-scale problem unto itself. But taken together, they represent world water woes of considerable proportions. Overpopulation, poorly planned development, inefficiency, and climate change all advance these problems to varying degrees. Overpopulation is an obvious contributor. Demographers predict a peak global population of 9–10 billion near the middle of this century. But where will all the water needed come from? Much of the world already is withdrawing 20–40% of the total available average freshwater, leaving people vulnerable to periodic droughts. Poorly planned development contributes, too. Everyone wants to live “on the edge” where seawater beckons, but it doesn’t quench our thirst. Eighty percent of Australians and more than half of all people worldwide live along the coast. And the trend is rapidly increasing. Megacities develop where droughts once were not a problem. But now, tens of millions of people are crammed into a limited coastal region. The Los Angeles megalopolis from San Diego to Santa Barbara has enough water of its own to support ~1 million people, but soon the area will have >20 million inhabitants. Interbasin transfers are required, in this case, from Sierra Nevada snowmelt and the distant Colorado River. Inefficiency runs rampant. One mayor in Georgia recently told people not to drink so much tap water. How foolish! Did he never think instead to tell them to stopper
© 2007 American Chemical Society
their bathtubs and showers to collect the gray water and to use it to flush their toilets? Then, by all means, drink your full allotment of 2 L of H2O per day. For that matter, why don’t we constantly reuse gray water and prohibit outdoor irrigation of lawns entirely? Water reuse should become the norm. More than 400 irrigated golf courses are located in the desert of metropolitan Phoenix, Ariz. Need I say more? In the U.S., we heavily subsidize farmers with direct payments to irrigate crops such as corn and cotton from the already overdrawn Ogallala (High Plains) Aquifer. Does this make any sense in a country that espouses free trade? Irrigation consumes 70% of all water that’s withdrawn. The U.S. should follow the technological lead of Israel, the global conservation leader. Evidence of a worsening world water shortage is found in the increasing number of countries importing >10% of their grain supply—an indirect importation of water. Climate change is the thread that potentially runs through all of these problems. A warmer world melts continental glaciers, the source for life in many arid regions of the world. Water may be plentiful for a while as glacier melt swells rivers and streams, but it’s only ephemeral. A warmer world also causes changes in the distribution of rainfall and in the frequency of floods and droughts, both of which burden nations of people. For example, witness the wicked cycle of drought and flood in recent years in Mozambique and central Africa. It’s impossible to attribute any specific regional problem directly to climate change, but the hydrologic “flywheel” is spinning faster as the earth’s surface and oceans warm. In total, global warming will produce greater worldwide precipitation. But if rainfall patterns shift and floods increase, we will not benefit. By 2025, 1.8 billion people will live in countries with absolute water scarcity, according to UN estimates. Rich countries can adapt. But the future of developing countries is at stake. Taken together, these forces foreshadow a world water crisis if nations fail to directly address overpopulation, poor planning, inefficiency, and climate change.
Jerald L. Schnoor Editor
[email protected] December 1, 2007 / Environmental Science & Technology n 7953
