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. 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.