The World’s Most Important Sites for Nature: The First Global Review of Key Biodiversity Areas 
A new study reveals that with 16,596 sites identified worldwide — spanning 22.1 million km² and supporting more than 18,000 species — the KBA network now represents the most comprehensive global map of sites critical for biodiversity.
After several decades of different organisations using different approaches for identifying important sites for nature, the International Union for Conservation of Nature (IUCN) unified these by publishing the Global Standard for the Identification of Key Biodiversity Areas in 2016. This landmark document provides a unified set of criteria for identifying ‘sites of significance for the global persistence of biodiversity’. Now, almost ten years on, a newly published paper by over 50 authors from 19 countries provides the first global audit of the KBA approach. It synthesises the lessons learned and outcomes of applying the global standard, documenting the scale, and characteristics of KBAs, their use by governments, intergovernmental bodies and the private sector, as well as future priorities for the KBA approach.
Dive into the study: 
https://onlinelibrary.wiley.com/doi/10.1002/brv.70144