Geographic biases undermine environmental representativeness of European biodiversity data

Biases and gaps in biodiversity data lead to significant disparities in species descriptions and distribution patterns across taxonomic groups. Although various modelling approaches can help address these gaps, they require the available data to be environmentally representative. In this study, we use data from the Global Biodiversity Information Facility (GBIF) to examine geographical biases, data gaps, and spatial completeness patterns in species distribution records for the 20 main classes of terrestrial organism in Europe-the world's oldest region for taxonomic and natural history research. By identifying spatial units with complete inventories for each class, we assess their quantity, distribution, and capacity to represent the environmental variability of the European subcontinent. Our results reveal high spatial heterogeneity and substantial variation among taxa in the number of well-surveyed units. Vertebrates and vascular plants have several times more well-surveyed cells than invertebrates and mosses. In terms of environmental representativeness, the findings highlight the uncoordinated and opportunistic accumulation of biodiversity data and the urgent need for improved coverage. This situation raises concerns about the reliability of current biodiversity data for accurately characterizing species distributions and limits the effectiveness of species distribution models. Given the scale and urgency of the biodiversity crisis, waiting for complete and reliable data before taking conservation action is not a viable option.