By Richard Black Environment correspondent, BBC News

About 80% of the world's population lives in areas where the fresh water supply is not secure, according to a new global analysis.
Researchers compiled a composite index of "water threats" that includes issues such as scarcity and pollution.
The most severe threat category encompasses 3.4 billion people.
Writing in the journal Nature, they say that in western countries, conserving water for people through reservoirs and dams works for people, but not nature. [VER noticia completa en la web de la BBC]