By Ben Blanchard Tue Oct 24, 6:29 AM ET BEIJING (Reuters) - Humans are stripping nature at an unprecedented rate and will need two planets' worth of natural resources every year by 2050 on current trends, the WWF conservation group said on Tuesday. Populations of many species, from fish to mammals, had fallen by about a third from 1970 to 2003 largely because of human threats such as pollution, clearing of forests and overfishing, the group also said in a two-yearly report. "For more than 20 years we have exceeded the earth's ability to support a consumptive lifestyle that is unsustainable and we cannot afford to continue down this path," WWF Director-General James Leape said, launching the WWF's 2006 Living Planet Report. "If everyone around the world lived as those in America, we would need five planets to support us," Leape, an American, said in Beijing. People in the United Arab Emirates were placing most stress per capita on the planet ahead of those in the United States, Finland and Canada, the report said. Australia was also living well beyond its means. The average Australian used 6.6 "global" hectares to support their developed lifestyle, ranking behind the United States and Canada, but ahead of the United Kingdom, Russia, China and Japan. "If the rest of the world led the kind of lifestyles we do here in Australia, we would require three-and-a-half planets to provide the resources we use and to absorb the waste," said Greg Bourne, WWF-Australia chief executive officer. Everyone would have to change lifestyles -- cutting use of fossil fuels and improving management of everything from farming to fisheries. "As countries work to improve the well-being of their people, they risk bypassing the goal of sustainability," said Leape, speaking in an energy-efficient building at Beijing's prestigous Tsinghua University. "It is inevitable that this disconnect will eventually limit the abilities of poor countries to develop and rich countries to maintain their prosperity," he added. The report said humans' "ecological footprint" -- the demand people place on the natural world -- was 25 percent greater than the planet's annual ability to provide everything from food to energy and recycle all human waste in 2003. In the previous report, the 2001 overshoot was 21 percent. "On current projections humanity, will be using two planets' worth of natural resources by 2050 -- if those resources have not run out by then," the latest report said. "People are turning resources into waste faster than nature can turn waste back into resources." RISING POPULATION "Humanity's footprint has more than tripled between 1961 and 2003," it said. Consumption has outpaced a surge in the world's population, to 6.5 billion from 3 billion in 1960. U.N. projections show a surge to 9 billion people around 2050. It said that the footprint from use of fossil fuels, whose heat-trapping emissions are widely blamed for pushing up world temperatures, was the fastest-growing cause of strain. Leape said China, home to a fifth of the world's population and whose economy is booming, was making the right move in pledging to reduce its energy consumption by 20 percent over the next five years. "Much will depend on the decisions made by China, India and other rapidly developing countries," he added. The WWF report also said that an index tracking 1,300 vetebrate species -- birds, fish, amphibians, reptiles and mammals -- showed that populations had fallen for most by about 30 percent because of factors including a loss of habitats to farms. Among species most under pressure included the swordfish and the South African Cape vulture. Those bucking the trend included rising populations of the Javan rhinoceros and the northern hairy-nosed wombat in Australia.