The Millenium Ecosystem Assessment -- a four-year, $21-million US effort to collate all that is known about environmental degradation -- is painting a bleak picture about what we're doing to our planet.

An excerpt from the BBC story:

The world's bulging population has led to the creation of mega-cities Deforestation, climate change, and pollution are compromising economic and social progress in the world's poorest nations, a major report has found. The report was carried out by 1,300 researchers to collate all that is known about environmental degradation around the globe. The Millennium Ecosystem Assessment is one of the biggest scientific collaborations ever undertaken. Its main findings are being released at meetings in eight world cities. The assessment found that human activities, particularly the spread of modern agriculture, have caused irreversible changes to the natural world. It cited as an example the over-use of water for farming, which puts pressure on fresh drinking supplies. Land that has been farmed too intensively is also becoming barren. Such effects, the report argues, are severe enough to threaten the Millennium Development Goals.