Widespread aridification of the land surface causes substantial environmental challenges and is generally well documented. However, the mechanisms underlying increased aridity remain relatively underexplored. Here, we investigated the anthropogenic and natural factors affecting long-term global aridity changes using multisource observation-based aridity index, factorial simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6), and rigorous detection and attribution (D&A) methods. Our study found that anthropogenic forcings, mainly rising greenhouse gas emissions (GHGE) and aerosols, caused the increased aridification of the globe and each hemisphere with high statistical confidence for 1965–2014; the GHGE contributed to drying trends, whereas the aerosol emissions led to wetting tendencies; moreover, the bias-corrected CMIP6 future aridity index based on the scaling factors from optimal D&A demonstrated greater aridification than the original simulations. These findings highlight the dominant role of human effects on increasing aridification at broad spatial scales, implying future reductions in aridity will rely primarily on the GHGE mitigation.

地表广泛的干旱化造成了巨大的环境挑战，并且通常有据可查。然而，干旱增加的潜在机制仍然相对不足。在这里，我们使用基于多源观测的干旱指数、耦合模型比对项目第 6 阶段 (CMIP6) 的因子模拟以及严格的检测和归因 (D&A) 方法研究了影响长期全球干旱变化的人为和自然因素。我们的研究发现，人为强迫，主要是温室气体排放（GHGE）和气溶胶的增加，导致全球和每个半球的干旱加剧，1965-2014 年的统计置信度很高；温室气体导致干燥趋势，而气溶胶排放导致润湿趋势；而且，基于最优 D&A 的比例因子的偏差校正 CMIP6 未来干旱指数表现出比原始模拟更大的干旱。这些发现突出了人类影响在广泛空间尺度上增加干旱的主要作用，这意味着未来干旱的减少将主要依赖于温室气体减排。