Biodiversity Intactness Index
The Biodiversity Intactness Index (BII) estimates how much of an area’s natural biodiversity remains. It helps us understand past, current and future biodiversity changes. View a world map of the BII and find out more about how we calculate the BII.
If the BII is 90% or more, the area has enough biodiversity to be a resilient and functioning ecosystem. Under 90%, biodiversity loss means ecosystems may function less well and less reliably. If the BII is 30% or less, the area's biodiversity has been depleted and the ecosystem could be at risk of collapse.
What's causing biodiversity change?
View data for
Factors causing changes in biodiversity
The BII model driven by changes in other factors. Find out more.
Indicator: Biodiversity Intactness Index
Data set: Available through the NHM Data Portal
Related Museum project: PREDICTS
Project and research leads: Professor Andy Purvis and Dr Adriana De Palma
Data last updated: October 2021. Models now include site-level pressures, simple measures of landscape-scale pressures (as the fraction of the 0.25-degree grid cell converted to human use) and landscape history (how long ago human use first covered 30% of the land). Uncertainty ranges are given and are based on cross-validation, leaving out each major biome in turn.
Coming soon: Annual BII values for 2000-2021 based on one kilometre resolution land use and human population data.