The Living Planet Report, released every two years, shows trends in the global health of the planet - and 2016's numbers are terrible:
From 1970 to 2012, there was a 58 percent overall decline in populations of mammals, birds, reptiles, amphibians and fish. That means that, on average, these animals have more than halved their numbers in 40 years.
The average rate of population decrease, 2 percent per year, shows no sign of slowing down.
If this downward trend continues, species populations could decline by 67 percent from the 1970 baseline by 2020.
The Dodo talked with Colby Loucks, senior director of WWF's Wildlife Conservation Program, to try to understand the findings, their consequences and what people can do to help.
"By and large this trend is a negative trend," Loucks told The Dodo. "If this continues ... we're going to get to the point that two-thirds of the population will be lost."
Why this is happening
Humans are to blame. The impact human beings are having on the planet will be able to be detected in the earth's rock strata, the way meteorite strikes or major volcanic changes have been up until now. We are entering the Anthropocene age, the first time ever that a single animal (human beings) will have such a huge impact on the earth, pushing the whole planet toward a sixth mass extinction.