The world 's animal population has halved in 40 years as humans put unsustainable demands on Earth , a new report warns . The World Wide Fund for Nature 's Living Planet Index , released Tuesday , revealed the dramatic decline in animal species , and said the trend could cost the world billions in economic losses . Humans need one and a half Earths to sustain their current demands , it said . The index , which draws on research around WWF 's database of 3,000 animal species , is released every two years . This year 's has the starkest warning yet of the risks associated with the decline of wildlife . The fund notes that it 's relying on a never-before-used methodology in this year 's report , `` which aims to be more representative of global biodiversity . '' The index showed shows a 52 % decline in wildlife between 1970 and 2010 , far more than earlier estimates of 30 % . It is due to people killing too many animals for food and destroying their habitats . `` We are eating into our natural capital , making it more difficult to sustain the needs of future generations , '' the report said . Researchers from the Zoological Society of London looked at changes in populations of more than 3,000 species of mammals , birds , reptiles , amphibians and fish , tracking over 10,000 different populations . Photos : Spectacular wildlife around the world . The decline in animals living in rivers , lakes and wetlands is the worst -- 76 % of freshwater wildlife disappeared in just 40 years . Marine species and animals living on land suffered 39 % decline in their populations . Animals living in tropics are the worst hit by what WWF calls `` the biggest recorded threats to our planet 's wildlife '' as 63 % of wildlife living in tropics has vanished . Central and South America shows the most dramatic regional decline , with a fall of 83 % . And while the animals are suffering now , the long-term impact will be on people , the report said . Marco Lambertini , director general of WWF International , said `` protecting nature is not a luxury ... .it is quite the opposite . For many of the world 's poorest people , it is a lifeline . '' According to Lambertini , the threat to oceans could create economic losses of up to $ 428 billion by 2050 . The global fishing sector employs more than 660 million people , and fish provide more than 15 % of protein in people 's diet . Global food security is under threat as the demands of growing population drain the resources . Forests provide water , fuel and food for more than billion people , including 350 million of the world 's poorest people .
He estimates 52 % of wildlife died between 1970 and 2010 . The decline in animals living in rivers , lakes and ponds is the worst . The alarming trend could cost the world billions in economic losses .