"The cities, power plants and homes we build today will either lock society into damaging over-consumption beyond our lifetimes, or begin to propel this and future generations towards sustainable living," he added.

The "Living Planet" report, a balance sheet of the world's environment published every other year, showed relentless growth in demand on the earth's capacity to produce clean air, and to provide raw materials, food and energy.

Two years ago, the same report based on 2001 data said the world's population was already outstripping the earth's capacity to regenerate resources by just over 20 percent.

The 2006 edition of the WWF report said that figure had risen to 25 percent in 2003.

Humanity's "ecological foot print" tripled between 1961 and 2003, fuelled largely by the use of fossil fuels such as oil and coal, it added.

The WWF said carbon dioxide emissions from energy consumption were the fastest growing component of the index in that period, increasing more than ninefold.

Meanwhile, a survey of animal life from 1970 to 2003 found that terrestrial species had declined by 31 percent, freshwater species by 28 percent and marine species by 27 percent.

"This global trend suggests that we are degrading natural ecosystems at a rate unprecedented in human history," the report said.

Leape said: "It is time to make some vital choices. Change that improves living standards while reducing the impact on the natural world will not be easy."

Each person occupies an "ecological footprint" equivalent to 2.2 hectares (5.4 acres) in terms of their capacity to pollute or consume energy and other resources including food, while the planet can only offer them 1.8 hectares each, according to the report.

"Even moderate 'business as usual' is likely to accelerate these negative impacts," it said.

The WWF estimated that even a rapid reversal in consumption habits now would only bring the world back to 1980s levels -- when it was already over-consuming -- by 2040.

The United Arab Emirates (11.9 hectares per person) and the United States (9.6) again came at the top of the Living Planet's ranking of the environmental impact of countries, largely due to high energy consumption.

Finland and Canada overtook oil-producing and consuming Kuwait to take third and fourth place in the table.

Like other Nordic nations, Finland has relatively low energy consumption but its timber industry puts forests under strain, according to the WWF.

Australia, Estonia, Sweden, New Zealand and Norway made up the rest of the top ten of national ecological footprints, followed by Denmark, France, Belgium and Britain.

China's 1.2 billion people ranked 69th with a growing average footprint of 1.6 hectares. The WWF said the Asian giant's rapid economic development implied that it had "a key role in keeping the world on the path to sustinability".

The WWF's footprint for a country includes all the agricultural land, forest, and fishing areas required to produce the food, fibre, and timber it consumes.

It also assesses a nation's capacity to absorb the amount of wastes it produces while generating energy, as well as the space needed for its infrastructure.

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