Chapter 02 · Nature, land & waterBiodiversity & Nature
Biodiversity loss
Definition
The ongoing reduction in biological diversity at genetic, species and ecosystem levels. The IPBES Global Assessment (2019) — the most comprehensive assessment to date, drawing on ~15,000 sources — concluded that nature is declining at rates unprecedented in human history: around one million of an estimated eight million species face extinction, many within decades, without transformative action.
References
~1 million species threatened; five direct drivers; indirect drivers; 80% of SDG targets undermined; transformative change finding.
Assessment scope (~15,000 sources, 145 authors, 50 countries); driver ranking; human-activity attribution.
Overview
What it means
IPBES ranks five direct drivers in descending order of impact: changes in land and sea use; direct exploitation of organisms (overfishing, logging, hunting); climate change; pollution; and invasive alien species. Behind them sit indirect drivers — population growth, consumption and production patterns, and governance failures.
The same assessment warned that biodiversity decline undermines progress on 80% of assessed SDG targets, reframing it as a development and security issue.
How it is used
"Biodiversity loss" anchors the Kunming-Montreal Global Biodiversity Framework's mission to halt and reverse loss by 2030, and nature-related financial risk frameworks (TNFD) that treat it as a systemic economic risk. Trend measures include the Living Planet Index and Red List Index.
Why it matters
Biodiversity loss is one of the planetary boundaries judged already transgressed, and its feedbacks with climate change (deforestation, ocean stress) make the two crises mutually reinforcing — the basis for treating nature as core sustainability infrastructure rather than a side issue.