Global populations of mammals, birds, amphibians, reptiles and fish have suffered an average two-thirds' decline in less than half a century. This has contributed to environmental degradation, leading to the emergence of zoonotic diseases such as COVID-19, according to WWF's Living Planet Report, 2020.

The Living Planet Index (LPI) shows that the factors believed to increase the planet's vulnerability to pandemics, including land-use change and the use and trade of wildlife, were also some of the drivers behind the 68 per cent average decline in global vertebrate species population between 1970 and 2016.