Despite substantial progress in understanding global biodiversity loss, major taxonomic and geographic knowledge gaps remain. Decisionmakers often rely on expert judgement to fill knowledge gaps, but are rarely able to engage with sufficiently large and diverse groups of experts. To improve understanding of the perspectives of thousands of biodiversity experts worldwide, we conducted a survey and asked experts to focus on the taxa and freshwater, terrestrial, or marine ecosystem they know best. We identified biodiversity experts as corresponding authors of papers published on the topic of biodiversity in scientific journals indexed in the Web of Science over the decade from January 2010 to December 2019. Focusing on the taxa and ecosystems they know best, these experts estimated past and future global biodiversity loss, which was defined in the survey as the percentage of species that are globally threatened or extinct. Experts also ranked the direct and indirect drivers of global biodiversity loss and estimated its impacts on ecosystem functioning and nature's contributions to people. We received 3,331 responses from biodiversity experts who live in 113 countries and who research biodiversity in nearly all (187) countries, including all major habitats in freshwater, terrestrial, and marine ecosystems. The data provided here are the 3,331 responses (rows) to survey questions (columns).