Hundreds of thousands of different species of animals and plants are facing extinction because of human activity, according to the United Nations.
The full report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) will be released later today and is expected to say this biodiversity crisis is on a par with - and maybe exceeds - climate change.
But what is biodiversity? And why does it matter to humans?
BBC environment reporter Laura Foster explains.