Earthworm communities in soils worldwide - and the critical ecosystem functions they provide - could be substantially impacted by continued climate change, according to a new report that evaluated data from nearly 7,000 sampled sites in 57 countries across the globe. This could result in cascading effects throughout terrestrial ecosystems in ways that are yet unclear. Earthworms are a highly diverse collection of organisms abundant in soils spanning the globe. While often unseen, their labor can have a transformative impact on their soil environments; as earthworms tunnel and eat their way through their subterranean domain, they perform vital functions like soil stabilization, organic decomposition and nutrient cycling throughout ecosystems. However, despite the critical role pf these "ecosystem engineers," little is known about global earthworm diversity and distribution, or the threats they face. Understanding these global patterns is important in predicting how changes in earthworm communities, due to climate change, for example, could alter the key ecosystem functions and services they provide. Helen Phillips and colleagues - an international team of 141 researchers from 35 countries worldwide - compiled a comprehensive dataset of earthworm communities to map global patterns in diversity and abundance, evaluate the environmental drivers that shape earthworm biodiversity, and model local earthworm communities. Their results show that climatic variables, specifically precipitation and temperature, are the most important predictors of earthworm biodiversity at global scales. Unlike many plant and animal species, where biodiversity peaks in the tropical lower latitudes, Phillips et al. discovered that earthworm species richness and abundance were typically greatest in the mid-latitudes. The results underscore that earthworm distributions are highly sensitive to climate. However, it remains unclear how earthworm communities will respond to ongoing climate change or what impacts to them might mean for the overall functioning of terrestrial ecosystems, writes Noah Fierer in a related Perspective.