Human beings are running up an unsustainable "overdraft" on the planet's natural resources, and standards of living will start to plummet in less than 30 years if changes are not put in place immediately, a leading international conservation organization said Tuesday.
Releasing its fourth Living Planet Report, WWF International said humans are currently using more than 20 percent more natural resources each year than can be regenerated, and that figure would skyrocket in the next 50 years.
The organization said humans should take control of their destiny now by moving away from fossil fuels for energy, promoting education and health care to control population as well as conserving and restoring natural ecosystems.
There should be a better balance between consumption in rich and poor countries, and resources should be replenished as they are used, it said.
The report was issued 50 days before the start of the World Summit on Sustainable Development in Johannesburg, South Africa.
"The fact that we live on a bountiful planet, but not a limitless one presents world leaders ... with a clear challenge," said Claude Martin, director-general of WWF International.
"Ensuring access to basic resources and improving the health and livelihoods of the world's poorest people cannot be tackled separately from maintaining the integrity of natural ecosystems."
The report estimates that the planet has about 11.4 billion hectares (28.2 billion acres) of productive land and sea, or 1.9 hectares (4.7 acres) for each of the 6 billion people on the planet.
Globally, humans are exceeding that possibility, consuming about 2.3 hectares (5.6 acres) of natural resources per person, the report says. But there are wide differences -- the average African or Asian consumes less than 1.4 hectares (3.5 acres) per person, while Europeans average 5 hectares (12.4 acres) and North Americans 9.6 hectares (23.7 acres).
The over-consumption is eating into the earth's stock of forest, fish and fertile soil and is dumping excess carbon dioxide emissions in the atmosphere, WWF said. That cannot go on indefinitely, it said.
Based on U.N. estimates that the world's population will grow to 9 billion by 2050, WWF projected that human welfare would continue to rise until around 2030 and then fall back dramatically when the planet can no longer sustain its population. That scenario could be improved if new technologies are found to improve the efficiency of resource use.
A WWF survey of animal life in three environments across the planet also found a massive drops in population.
A study of freshwater animals found that numbers had fallen by 54 percent from 1970 to 2000. The marine population was down 35 percent and forest animals by 15 percent, WWF said.
"We do not know exactly what the result will be of running this massive overdraft with the earth. What is clear, though, is that it would be better to control our own destiny, rather than leave it up to chance," said Jonathan Loh, author of the report.
"At the summit, world leaders will have a magnificent opportunity to address the root causes of our obvious failure to achieve sustainable development and set us on the path to a truly sustainable future."