Monitored wildlife populations down 73%

Biodiversity is harder to measure than temperature, so scientists rely on two big indicators. The first, the Living Planet Index, tracks nearly 35,000 populations of 5,495 vertebrate species and finds an average 73% decline in population sizes from 1970 to 2020.

Where losses are steepest

The average hides sharp variation:

• Freshwater populations have fallen about 85%.
• Terrestrial populations about 69%, marine about 56%.
• Latin America and the Caribbean show the steepest regional drop, around 95%.

An important clarification: this is an average rate of decline across populations, not the share of animals or species that have disappeared. It is a measure of shrinking abundance, and it is severe.

The extinction lens

The second indicator, the IUCN Red List, has assessed about 172,600 species, of which roughly 48,600 are threatened with extinction — around 28% of those evaluated. Amphibians, reef-building corals, sharks and rays, and cycads are among the most imperilled groups.

The drivers

The dominant pressures are habitat loss (especially deforestation and farmland expansion), overexploitation, invasive species, pollution and, increasingly, climate change. Governments have adopted a global target to protect 30% of land and sea by 2030, but coverage and funding remain well short.