Asian water shortages may not be as bad as previously thought

15 Jun 2010

Some of Asia’s mighty rivers will be hit hard by climate change, with nearly 60 million people facing potential food shortages as a result, but other rivers will see little change, as was previously predicted, according to a new study this month in the journal Science.

It’s rare to get good news on climate change–but if the study’s predictions come true, China and much of India could be better off than many scientists had expected.

However, two other major rivers—the Indus, which feeds Pakistan, and the Brahmaputra, which runs through eastern India and Bangladesh—could lose large amounts of water, resulting in a huge rise in hunger.

Asia’s “water tower’—the snow and glaciers in the Himalayas and Tibetan plateau—supplies some of the world’s largest rivers.  In turn, these rivers support nearly 1.5 billion people, or one-fifth of the world’s population.  Some previous reports argued that most of these rivers would be hit hard as temperatures rise, forcing river flows to dwindle to a trickle.

One such claim—a major report of the Intergovernmental Panel on Climate Change published in 2007—was retracted (pdf) earlier this year as a mistake.

New Theories

In the new study, lead researcher and Utrecht University hydrologist Walter Immerzeel said, “We project significant decreases in discharge–but the rivers won’t run dry.”

The new study used climate models to estimate what would happen by mid-century if greenhouse gas emissions continued to rise under “a business-as-usual scenario,” climbing to about double current yearly emissions.

The meltwater from the snowpack and glaciers “plays only a modest role for the Ganges, Yangtze, and Yellow rivers,” the study said, explaining that these river basins depend more on rainwater than glacial melt.  However, it “it extremely important in the Indus basin and important for the Brahmaputra basin.”

With today’s often inefficient agricultural systems, the drop in water by mid-century would mean that Pakistan, eastern India, and crowded Bangladesh would struggle to feed growing populations.

The Indus would be capable of supporting about 25 million fewer people, the study estimates.  In the Bramaputra basin, the drop in flows would mean river-based irrigation could support just 27 million people—less than half the current population.

So, the researchers argue, these hard-hit areas would likely need to revamp their agricultural methods to use water more efficiently.

They might need “different crop varieties which are less water-consuming,” said Immerzeel, or they could adapt by “providing economic incentives to farmers to use less water.

For more on Asia’s water tower:

National Geographic magazine: Tibetan Plateau

National Geographic News: “Goddess” Glacier Melting in War-Torn Kashmir

National Geographic News: “Venice of Asia” Canals Disappearing

For more on water and how to conserve, visit National Geographic’s freshwater website.

© 1996-2008 National Geographic Society. All rights reserved.


books I've read on failure & grace

The World Without Us
The Last Oil Shock: A Survival Guide to the Imminent Extinction of Petroleum Man
A Paradise Built in Hell: The Extraordinary Communities That Arise in Disaster
Hell and High Water: Global Warming--the Solution and the Politics--and What We Should Do
The Worst Hard Time: The Untold Story of Those Who Survived the Great American Dust Bowl
The Tipping Point
Three Cups of Tea: One Man's Mission to Promote Peace... One School at a Time
The Upside of Down: Catastrophe, Creativity and the Renewal of Civilization
Out of Poverty: What Works When Traditional Approaches Fail
The Little Ice Age: How Climate Made History, 1300-1850
Confessions of an Eco-Sinner: Tracking Down the Sources of My Stuff
Deep Economy: The Wealth of Communities and the Durable Future
The Geography of Bliss: One Grump's Search for the Happiest Places in the World

Mason's favorite books »