The Earth is facing another mass extinction event, and this time it's not an ice age, a world-shaking meteor or a plague culling animal species -- it's humanity.
Human activity, including ongoing development, destruction of animal habitats, hunting, poaching, pollution and over-consumption is the culprit, scientists say, contributing to a 58 percent loss of global wildlife since 1970.
That's according to the World Wildlife Fund's Living Planet report, billed as the most extensive survey of wildlife in history. Researchers tracked 3,700 different species of animals, from mammals to birds, fish, amphibians and reptiles.
They also pulled information from existing peer-reviewed surveys published in science journals, as well as statistics from governments across the globe and surveys conducted by conservation groups.
If the trend continues, the WWF says, the earth will lose two-thirds of its wildlife by 2020, including iconic species like elephants and tigers -- both of which are under constant threat from poachers -- as well as gorillas, lions, the black rhinoceros, penguins, bears, killer whales, chimpanzees and cheetahs.
“We have lost one half of the animal population and knowing this is driven by human consumption, this is clearly a call to arms and we must act now,” Mike Barrett, the WWF's director of science, told The Guardian.
And it's not just individual species that are in danger. The world's ecology is like a Jenga puzzle, scientists say, with potentially disastrous consequences if animals that fill an important ecological niche are removed from the wild.
The extinction of keystone species could throw nature's delicate balance into a tailspin, with the consequences rippling out in unforeseen ways.
"We're gradually destroying our planet’s ability to support our way of life,” Carter Roberts, president and CEO of WWF, wrote in the report. “But we already have the knowledge and tools to avoid the worst predictions. We all live on a finite planet and its time we started acting within those limits.”
The WWF is calling on world leaders and governments to enact changes, including shifting to smarter food production methods that don't tax finite resources, reducing the ecological footprints of governments and companies, and always considering the value of "natural capital" in policy and development decisions.
People in first-world countries aren't seeing the worst of the biodiversity loss, the WWF warned, and decisions made by world powers disproportionately impact third-world nations.
“High-income countries use five times the ecological resources of low-income countries, but low income countries are suffering the greatest ecosystem losses,” said Keya Chatterjee, WWF’s senior director of footprint. “In effect, wealthy nations are outsourcing resource depletion.”