The carbon (C) balance in terrestrial ecosystems is primarily determined by inputs from net primary productivity and C outputs to the atmosphere through organic matter. Understanding the global C balance is crucial for predicting their current and future roles of terrestrial ecosystems as C sources or sinks in the context of global change. Drylands, covering nearly 45% of Earth's land surface, contribute significantly to net primary production (NPP) and influence the interannual variability of the terrestrial C sink. However, the controls on plant litter decomposition, a major pathway of C release, remain unclear in these ecosystems. Here, we present a global analysis of plant litter decomposition in drylands, using a dataset from 116 sites across six continents spanning diverse climates and ecosystems. We found that litter decomposition did not correlate with mean annual precipitation (MAP) or aridity at the global scale, challenging the paradigm that the quantity of rainfall received annually is the primary constraint on ecological processes in drylands. Instead, our analysis identifies mean annual temperature (MAT), precipitation-temperature synchrony, precipitation variability, and cloud-cover frequency as key drivers. Specifically, our model predicted faster decomposition rates in drylands with higher MAT, more synchrony between wet and warm seasons (monsoonal climate), larger precipitation variability, and litter with higher N content. Across drylands, decomposition correlated positively with both nitrogen and lignin content, in contrast to the negative lignin-decomposition relationship commonly observed in mesic ecosystems. Because MAT and solar irradiance strongly covary, apparent temperature effects may in part reflect radiation-driven processes, highlighting photodegradation as an important control, particularly in very arid zones. Given the ongoing expansion of drylands, rising temperatures and changes in precipitation variability under climate change, our results underscore the need to refine decomposition models beyond traditional aridity frameworks to accurately predict dryland contributions to the global C balance. Comprender el balance global de carbono (C) en los ecosistemas terrestres es esencial para anticipar su rol como fuentes o sumideros de C bajo el cambio global. Las zonas & aacute;ridas, que cubren casi el 45% de la superficie terrestre, aportan una fracci & oacute;n importante a la productividad primaria neta (NPP) e influyen en la variabilidad interanual del sumidero terrestre de C. Sin embargo, los factores que regulan la descomposici & oacute;n de la broza, una v & iacute;a clave de liberaci & oacute;n de C, siguen siendo poco claros en estos ecosistemas. Presentamos un an & aacute;lisis global de la descomposici & oacute;n de broza en zonas & aacute;ridas basado en datos de 116 sitios en cinco continentes que abarcan climas y ecosistemas diversos. Encontramos que las tasas de descomposici & oacute;n no se correlacionan con la precipitaci & oacute;n media anual (MAP) ni con la aridez, lo que cuestiona el paradigma de que la disponibilidad de agua es la principal limitante en las zonas & aacute;ridas. En cambio, la temperatura media anual (MAT), la sincron & iacute;a entre precipitaciones y temperatura, la variabilidad de las precipitaciones y la frecuencia de nubosidad emergen como los impulsores predominantes. Nuestro modelo predice descomposici & oacute;n m & aacute;s r & aacute;pida en zonas & aacute;ridas con MAT m & aacute;s altas, mayor coincidencia entre estaciones h & uacute;medas y c & aacute;lidas (climas monz & oacute;nicos), mayor variabilidad en las precipitaciones y broza con m & aacute;s N. A escala global, la descomposici & oacute;n se correlacion & oacute; positivamente con el contenido de nitr & oacute;geno y de lignina, en contraste con la relaci & oacute;n negativa entre lignina y descomposici & oacute;n t & iacute;pica de ecosistemas m & eacute;sicos. La fuerte covariaci & oacute;n entre MAT e irradiancia solar sugiere que los efectos atribuidos a la temperatura pueden estar enmascarando controles abi & oacute;ticos importantes, especialmente la fotodegradaci & oacute;n, en las zonas m & aacute;s & aacute;ridas. Dada la expansi & oacute;n de las zonas & aacute;ridas y los cambios proyectados en temperaturas y variabilidad de las precipitaciones, los resultados destacan la necesidad de redefinir los modelos de descomposici & oacute;n m & aacute;s all & aacute; de los enfoques basados en aridez para predecir con precisi & oacute;n su contribuci & oacute;n al balance global de C.