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Biodiversity Intactness Index

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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.

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Data details

Indicator: Biodiversity Intactness Index

Data set: Available through the NHM Data Portal

Geographical standards used: UN M49 Standard, Natural Earth

Related Museum project: PREDICTS

Project and research leads: Professor Andy Purvis and Dr Adriana De Palma

Published papers: Hudson et al. 2017; Hudson et al. 2016; LeClere et al. 2020; and Hill et al. 2018

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.