Resources used after that date represent a kind of ecological overdraft.

Year by year, the day has been coming earlier; and this year it falls today.

Andrew Sims from the Global Footprint Network says current consumption levels are too high.

"The point will come in nature, where you hit perhaps a form of what you might call environment bankruptcy," he said.

"You can't bounce back from it in the way that you can if, for example, a bank goes bust in the economy.

"We're talking about the life-supporting ecosystems that the planet provides us. We do not want to see those go bankrupt." © 2007 Australian Broadcasting Corporation