Their warning came after a report revealed that populations of animals and plants have plummeted by a third over the last 35 years as a result of hunting, overfishing, habitat destruction and the changing climate.

Humans are increasingly living beyond their means and the world is heading for an 'ecological credit crunch', according to the Living Planet Report.

Prepared by the World Wide Fund for Nature and the Zoological Society of London, the report is designed to be a health check for the Earth.

It looked at the fortunes of 1,686 species of animal and plant since the 1970s, based on around 5,000 ongoing monitoring projects.

The report found that populations of all the species fell by 30 per cent between 1970 and 2005.

The number of land animals fell by a quarter between 1970 and 2005, while freshwater animals were down by 29 per cent.

Mark Wright, of WWF, said: 'The report shows that populations are dramatically declining. There is no doubt we are in a period of mass extinction comparable to those from millions of years ago.'

Dinosaurs were wiped out 65million years ago when a comet crashed into the Gulf of Mexico sending dust into the atmosphere that blocked out the sun.

As well as charting the decline of species, the report looked at each country's 'ecological footprint' - the amount of land and sea it needs to provide its natural resources and absorb its waste.

WWF said that if pressure on water, land and wildlife and the output of carbon emissions continue to rise at the current rate, we will need two planets by the 2030s to maintain our lifestyles.

Jonathan Loh, of the ZSL, said: 'We are acting ecologically in the same way as financial institutions have been behaving economically - seeking immediate gratification without due regard for the consequences.'

Via Dailymail