Brahma Chellaney -- Asia's megacities are running out of water

[FearLess]

Asia's cities are ballooning, and the accompanying upsurge in the consumption of water and production of waste in urban areas is placing new pressures on the environment.

Home to 53% of the world's urban po[CENSORED]tion, Asia has the highest concentration of megacities, including Shanghai, Tokyo, Karachi and Beijing. Not only are Asia's cities big and numerous, they are among the most polluted. The urban explosion has made providing safe water and sanitation a massive challenge for the region.

Historically, the availability of local water resources has determined not only where major cities have been established but how well they have fared. But in Asia, rapid -- and often unplanned -- urban growth in recent decades has overwhelmed water systems.

Asia's per capita water availability is already the lowest of any continent. Fast economic growth, coupled with breakneck urbanization and changing lifestyles, has made a difficult situation worse. In 2012, slightly over half of the world's po[CENSORED]tion lived in urban areas. By 2050, that ratio is projected to jump to more than two-thirds, with much of that growth taking placing in Asia.

The region's urba

The region's urbanization is fueling demand for water not just for municipal use but also for manufacturing and agriculture. And changing diets, especially an increased preference for meat -- the production of which is notoriously water-intensive -- are compounding water challenges. Asia needs to make substantial water savings in agriculture to quench the thirst of its expanding cities. Some of the largest urban centers -- from Beijing and Manila to Jakarta and Dhaka -- are already at risk of running out of water.