Drylands cover around 40% of the global landmass, support a population of around 2 billion people, 90% of whom live in developing countries, and support nearly 50% of the world’s livestock and cultivated land. Groundwater is often a critically important water resource in such regions acting to ‘buffer’ the variability in climate and provide reliable freshwater both for humans and other ecology. Despite its importance, significant challenges are still faced in understanding and modelling dryland climate-groundwater interactions globally. This talk will begin by outlining how the concept of ‘groundwater response time’ enables us to understand the relationship between climate variability and the presence of persistent sources of freshwater in global drylands. This idea will then be used to explore the role that groundwater hydro-refugia likely played in enabling human resilience to climate change over the past 2 million years since the origin of our own genus Homo. Finally, recent progress in understanding climate-groundwater interactions in dryland environments will be presented to suggest how global modelling efforts can be improved to enable more robust future groundwater management and climate change resilience.