Sea "Dead Zones" on the Increase

It has arrived early; it's bigger than ever and it promises a summer of death and destruction. The annual "dead zone" in the Gulf of Mexico - starved of oxygen, and thus killing fish and underwater vegetation - has appeared earlier than usual this year.
This is just one sign of a rapidly growing crisis. The number of similar dead zones in the world's seas has doubled every decade since 1960, as a result of increasing pollution. The United Nations Environment Programme says that there are now 146 of them worldwide, mainly around the coasts of rich countries. Its executive director, Klaus Töpfer, calls their growth "a gigantic, global experiment ... triggering alarming, and sometimes irreversible, effects".