Human action is driving some one million plant and animal species to annihilation, according to the most comprehensive assessment ever conducted on life on Earth. Extinction now threatens a quarter of all of Earth’s species — and that estimate is conservative.

That includes the kind of beloved megafauna that are the subjects of traditional conservation efforts. Tigers, for instance, are now absent from 96 percent of their historic territory. But over 40 percent of amphibian species, one-third of all reef-forming corals, one-third of all marine mammal species, and 10 percent of insect species face extinction, too, says the United Nations’ Intergovernmental Science-Policy Platform on Biodiversity on Ecosystem Services (IPBES) report summary for policymakers.

Most extinctions go unnoticed. It can take years for scientists to learn that a plant or creature is gone forever. But the consequences of an extinction can be complex. Like a game of Jenga, when one piece is removed, the whole structure is compromised, and eventually, the entire ecosystem can collapse.