Animal populations shrunk an average of 69% over the last half-century, a report says

Cattle graze near a fire in Amazonas, Brazil, on Sept. 22. A new report analyzed years of data on wildlife populations across the world and found a downward trend in the Earth's biodiversity. (Michael Dantas/AFP via Getty Images)

Global animal populations are declining, and we've got limited time to try to fix it.

That's the upshot of a new report from the World Wildlife Fund and the Zoological Society of London, which analyzed years of data on thousands of wildlife populations across the world and found a downward trend in the Earth's biodiversity.