Global State of Biodiversity and Loss

TLDR

Biodiversity is a central component of Earth’s life support systems and directly relevant to human societies. The study examines the dimensions and nature of terrestrial biodiversity and reviews scientific facts on its loss rate and drivers. The authors analyze terrestrial biodiversity dimensions and assess drivers of loss. The total number of eukaryotic species is estimated at 5–15 million (≈7 million), with uneven distribution concentrated in tropical ecosystems and hotspots that are threatened by habitat destruction, leading to extinction rates hundreds of times higher than the geological baseline and making biodiversity loss the only truly irreversible global environmental change today.

Abstract

Biodiversity, a central component of Earth's life support systems, is directly relevant to human societies. We examine the dimensions and nature of the Earth's terrestrial biodiversity and review the scientific facts concerning the rate of loss of biodiversity and the drivers of this loss. The estimate for the total number of species of eukaryotic organisms possible lies in the 5–15 million range, with a best guess of ∼7 million. Species diversity is unevenly distributed; the highest concentrations are in tropical ecosystems. Endemisms are concentrated in a few hotspots, which are in turn seriously threatened by habitat destruction—the most prominent driver of biodiversity loss. For the past 300 years, recorded extinctions for a few groups of organisms reveal rates of extinction at least several hundred times the rate expected on the basis of the geological record. The loss of biodiversity is the only truly irreversible global environmental change the Earth faces today.