Biodiversity refers to the variety and variability of life on Earth. It can be measured across scales from the genetic, species, and ecosystem levels. Loss of biodiversity undermines the stability of the planet and the systems that support all life. Human societies across the globe rely on the services that ecosystems provide, from fresh water to fertile soil, food, and medicine. Ecosystems that have been weakened by the loss of species diversity are less able to provide those services, especially in light of a fast-growing human population across the globe.