Medical staff use a Geiger counter to screen a woman for possible radiation exposure at a public welfare centre in Hitachi City, Ibaraki, in this file picture taken March 16, 2011. The world's population will reach seven billion on Oct 31, 2011, according to projections by the United Nations. The environment provides trillions of dollars in benefits to the global economy, the United Nations says, yet many of these benefits are under threat from pollution, deforestation, climate change and over-extraction as seven billion people consume more of the Earth's finite resources. Mankind's immense pressure on the planet is causing the fastest extinction of species in millions of years and is rapidly heating up the planet, threatening more extreme weather. [Photo/Agencies]