<p>Sand dunes develop when there is a source of sediment and adequate wind. Dune morphology and occurrence can then be used to infer sediment source distribution and formative climate conditions. This is useful where direct climate observation is challenging on Earth, other planets, and the past. However, there has been no complete and accurate digital map of the occurrence of Earth’s sand dunes with distinguishable morphologies. Here we present that map and demonstrate that in arid environments dune presence is mostly explained by convergent transport and source proximity, whereas in wetter climates wind strength is an additional constraint. By limiting analysis to dunes identified from globally available imagery and topographic data, we produce a consistent dataset useful for inferring myriad aspects of geology and climate, and improving understanding of aeolian landscapes. We provide an example, using barchan dune orientations, to demonstrate a trade-off between inference of sediment and wind characteristics.</p>