Andy Purvis at IPBES:
The IPBES Global Assessment estimated that 1 million animal and plant species are threatened with extinction. It also documents how human actions have changed many aspects of nature and its contributions to people; but species threatened with extinction resonate with the media and the public in ways that degradation of habitats and alteration of rates of ecosystem processes perhaps don’t, so the figure was widely reported.
Because only the Summary for Policymakers has so far been made available, it wasn’t clear where the figure of 1 million threatened species came from. Some journalists and researchers asked me, so I explained it to them, and will explain it again here. Some other writers, often with a long history of commenting critically on reports highlighting environmental concerns, instead railed against the Global Assessment in general and the figure of 1 million threatened species in particular. Given that these writers often advance empty or bogus arguments, I thought it would be also be useful to explain why these arguments are wrong.
I have therefore written this blog post in the form of thirteen questions and answers. Before that, however, there are two points I should make.
First, I will declare my interest: I am one of the hundreds of authors of the Global Assessment, and I worked on the estimate of how many species are threatened.