Understanding the biodiversity crisis

The crisis in numbers

The International Union for Conservation of Nature (IUCN) maintains the Red List of Threatened Species, the global reference for measuring extinction risk. In its update of 9 July 2026, it covered 175,909 assessed species, of which 49,505 are threatened with extinction: slightly more than one in four.

That number keeps rising from one update to the next. In October 2025, the Red List covered 172,620 assessed species, of which 48,646 were threatened. Part of the increase simply reflects the fact that scientists assess new species every year. But it also reflects very real declines.

And these species are only part of life on Earth: the vast majority of known species have not yet been assessed. The true number of threatened species is unknown, and almost certainly higher.

Good news, too

The same updates also record progress. In October 2025, the green turtle moved from Endangered to Least Concern, after decades of protecting nesting beaches and reducing bycatch. At the July 2026 update, IUCN Director General Grethel Aguilar put it simply: “nature conservation works”.

Understanding why species decline already tells us much of what it takes to save them.