Cohen Sean, Pincus Robert
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA.
Sci Adv. 2025 May 9;11(19):eadv6191. doi: 10.1126/sciadv.adv6191.
Surface warming is projected to increase global mean rainfall primarily by increasing the radiative cooling of the atmosphere. However, the radiative mechanisms which cause cooling to increase are not well understood. Here, we show that changes in cooling are driven primarily by changes in atmospheric opacity, particularly within the water vapor window. This suggests that changes in mean rainfall are primarily controlled by the thermodynamic and spectroscopic properties of Earth's main greenhouse gases: water vapor and carbon dioxide. Consistent with comprehensive general circulation models, our results explain why mean rainfall increases with surface warming at about 2% per kelvin, why this rate is largely unchanged over numerous doublings of atmospheric carbon dioxide, and why mean rainfall decreases in hothouse climates.
预计地表变暖将主要通过增加大气的辐射冷却来增加全球平均降雨量。然而，导致冷却增加的辐射机制尚未得到很好的理解。在这里，我们表明冷却的变化主要是由大气透明度的变化驱动的，特别是在水汽窗口内。这表明平均降雨量的变化主要受地球主要温室气体：水汽和二氧化碳的热力学和光谱特性控制。与综合通用循环模型一致，我们的结果解释了为什么平均降雨量随地表变暖以每开尔文约2%的速度增加，为什么在大气二氧化碳多次翻倍的情况下这个速率基本不变，以及为什么在温室气候中平均降雨量会减少。
