Rethinking desert definitions: Bridging the gap between science, policy, and conservation.

Deserts are often misperceived as desolate, non-productive landscapes. This perception contributes to the misuse of terms like 'semiarid' and 'desertification', creating ambiguity in how deserts are defined and geographically delineated. Such conceptual confusion can hinder effective policy by obscuring what constitutes a desert and where they occur. We identify key incongruencies between climatic and ecological approaches to classifying deserts, revealing nearly 12 million km2 of distinct, non-overlapping desert regions globally. A new, more comprehensive desert classification is needed to better support policy goals in desert regions. This refined understanding is especially urgent as human pressures accelerate land degradation across drylands-a process the United Nations Convention to Combat Desertification refers to as 'desertification'. However, the term is misperceived as the expansion of deserts while ignoring land degradation in actual desert regions. We challenge these misconceptions and advocate for a more nuanced understanding of deserts to strengthen scientific and policy frameworks.