Global populations of wild animals could be down by two-thirds by 2020 without reform to food and energy systems, according to a devastating new report out Thursday.

The analysis by the World Wide Fund for Nature (WWF) and the Zoological Society of London finds that animal populations dropped 58 percent between 1970 and 2012. Without radical action, the world could witness a decline of 67 percent by 2020.

The annual Living Planet Index is the most comprehensive study to date, the organizations said. Since the mid-twentieth century, use of natural resources has gone up dramatically, harming biodiversity and other critical ecosystems. And now, as scientists suggest we’ve entered into a new geological epoch created by human activity—the Anthropocene—the report states that we are endangering the natural systems we rely upon, and are faced with a “dual challenge” to keep the earth habitable for animals and people.

“Wildlife is disappearing within our lifetimes at an unprecedented rate,” said Marco Lambertini, director general of WWF International. “This is not just about the wonderful species we all love; biodiversity forms the foundation of healthy forests, rivers, and oceans. Take away species, and these ecosystems will collapse along with the clean air, water, food, and climate services that they provide us.”

“We have the tools to fix this problem and we need to start using them now if we are serious about preserving a living planet for our own survival and prosperity,” Lambertini said.

The top threats to species identified in the report—fish, birds, mammals, amphibians, and reptiles, from gorillas to salamanders—are directly linked to human activity. That includes habitat loss and overexploitation of wildlife, both of which are in part a result of global food production for a booming population. The report notes that agriculture takes up about one-third of the Earth’s territory and accounts for 70 percent of water use.