The compilation of scientific knowledge at a global scale is key to tackling many global environmental problems including recent biodiversity loss. One large challenge is the heterogeneity in the geographical coverage of existing information on biodiversity. Nevertheless, the key barriers to the compilation of biodiversity information at a global scale have yet to be identified. Here we show that economics, language and geographical location played an important role in explaining spatial variations in data availability in four different types of biodiversity databases. The proportion of English speakers as well as GDP per capita affected the number of records per km² in each country positively. The distance from host organisations also affected data availability negatively but not in the best-known database. Biodiversity data were consequently under-collected from biodiversity-rich countries. Our results demonstrate that efforts to solve global environmental problems will benefit by focusing on scientific education, research and communication in low-GDP countries with fewer English speakers, located far from Western countries. Language, economics and geographical location of countries should equally be taken into account when trying to understand the drivers of spatial heterogeneity in scientific knowledge and for the development of science at the global scale.