Nicholas C. Wu , Rafael P Bovo, Urtzi Enriquez-Urzelai, Susana Clusella-Trullas, Michael R. Kearney, Carlos Navas, Jacinta D Kong

Species exposed to prolonged drying are at risk of population declines or extinctions. Understanding species' sensitivity to water loss and microhabitat preference, or ecotype, is therefore vital for assessing climate change risks. Here, we mapped global areas where water-sensitive vertebrates, i.e., anurans, will face increasing aridity and drought, analysed ecotype sensitivity to water loss, and modelled behavioural activity impacts under future drought and warming scenarios. Predictions indicate 6.6% to 33.6% of anuran habitats will become arid-like by 2080–2100, with 15.4% to 36.1% exposed to worsening drought, under an intermediate to high emission scenario, respectively. Critically, arid conditions are expected to double water loss rates. Biophysical models demonstrated a 11.45 ± 8.95% reduction in anuran activity under combined drought and warming, compared to the 6.74 ± 3.95% reduction from warming alone in the warmest quarter. These findings underscore the pervasive synergistic threat of warming and environmental drying to anurans.