The 600-page World Water Development Report — more than two years in the making and based on contributions from 23 U.N. agencies and commissions — examines major aspects of water use and management, from the growth of cities to the threat of looming water wars between countries.

The report predicts that as many as seven billion people in 60 countries could face water scarcity by 2050, but the full extent of the global water crisis will depend on factors such as population growth and policy-making. Climate change will account for an estimated 20 percent of this increase in global water scarcity.

Pollution is also a major problem, with developing countries continuing to be the most affected. Despite widely available evidence of the crisis, political commitment to reverse these trends has been lacking, according to the report. The United Nations is charged with cutting the number of people lacking reliable access to clean water in half by 2015. See www.usembassy.it/file2003_03/alia/a3030516.htm.