Rising emissions of anthropogenic greenhouse gases (GHG) have led to tropospheric warming and stratospheric cooling over recent decades. As a thermodynamic consequence, the troposphere has expanded and the rise of the tropopause, the boundary between the troposphere and stratosphere, has been suggested as one of the most robust fingerprints of anthropogenic climate change. Conversely, at altitudes above ∼55 km (in the mesosphere and thermosphere) observational and modeling evidence indicates a downward shift of the height of pressure levels or decreasing density at fixed altitudes. The layer in between, the stratosphere, has not been studied extensively with respect to changes of its global structure. Here we show that this atmospheric layer has contracted substantially over the last decades, and that the main driver for this are increasing concentrations of GHG. Using data from coupled chemistry-climate models we show that this trend will continue and the mean climatological thickness of the stratosphere will decrease by 1.3 km following representative concentration pathway 6.0 by 2080. We also demonstrate that the stratospheric contraction is not only a response to cooling, as changes in both tropopause and stratopause pressure contribute. Moreover, its short emergence time (less than 15 years) makes it a novel and independent indicator of GHG induced climate change.

近几十年来，人为温室气体 (GHG) 排放量的增加导致对流层变暖和平流层变冷。作为热力学结果，对流层已经扩大，对流层和平流层之间的边界对流层顶的上升被认为是人为气候变化最有力的指纹之一。相反，在大约 55 公里以上的高度（在中间层和热层），观测和建模证据表明压力水平的高度向下移动或在固定高度降低密度。中间的层，平流层，尚未对其全球结构的变化进行广泛研究。在这里，我们表明这个大气层在过去几十年里大幅收缩，造成这种情况的主要驱动因素是温室气体浓度的增加。使用来自耦合化学-气候模型的数据，我们表明这种趋势将持续下去，到 2080 年，按照代表性浓度路径 6.0，平流层的平均气候厚度将减少 1.3 公里。我们还证明平流层收缩不仅是对降温的反应，因为对流层顶和平流层顶压力的变化都有贡献。此外，其短的出现时间（不到 15 年）使其成为温室气体引起的气候变化的一种新颖且独立的指标。我们还证明平流层收缩不仅是对冷却的反应，因为对流层顶和平流层压力的变化都有贡献。此外，其短的出现时间（不到 15 年）使其成为温室气体引起的气候变化的一种新颖且独立的指标。我们还证明平流层收缩不仅是对冷却的反应，因为对流层顶和平流层压力的变化都有贡献。此外，其短的出现时间（不到 15 年）使其成为温室气体引起的气候变化的一种新颖且独立的指标。