Biodiversity safeguards ecosystem services and functions worldwide.

Biodiversity loss threatens ecosystem services on which humanity depends, yet the strength, form and context-dependency of biodiversity-ecosystem service and biodiversity-ecosystem function relationships remain poorly quantified. Here we synthesize 423 studies to determine how biodiversity affects ecosystem functioning and service delivery. We show that regulating services, including water quality and pollination, often exhibit linear relationships, suggesting an additive role for diversity. While biodiversity enhances most functions and services, our effect-size analysis shows that oceanic 'blue carbon' sequestration is exceptionally sensitive, revealing how critical marine biodiversity is for climate mitigation. Conversely, services such as hazard regulation appear relatively insensitive to biodiversity, instead depending on a few functionally unique foundational species whose persistence nonetheless is interdependent on the wider community. Our new synthesis enables the forecasting of impacts, for example, that biodiversity loss will reduce pest regulation in countries experiencing population growth and intensive development, and it also highlights how ecosystem services might be used to anticipate future problems.