Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093.
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt, 60438, Germany.
Proc Natl Acad Sci U S A. 2022 Nov 16;119(46):e2210481119. doi: 10.1073/pnas.2210481119. Epub 2022 Nov 7.
How clouds respond to anthropogenic sulfate aerosols is one of the largest sources of uncertainty in the radiative forcing of climate over the industrial era. This uncertainty limits our ability to predict equilibrium climate sensitivity (ECS)-the equilibrium global warming following a doubling of atmospheric CO. Here, we use satellite observations to quantify relationships between sulfate aerosols and low-level clouds while carefully controlling for meteorology. We then combine the relationships with estimates of the change in sulfate concentration since about 1850 to constrain the associated radiative forcing. We estimate that the cloud-mediated radiative forcing from anthropogenic sulfate aerosols is [Formula: see text] W m over the global ocean (95% confidence). This constraint implies that ECS is likely between 2.9 and 4.5 K (66% confidence). Our results indicate that aerosol forcing is less uncertain and ECS is probably larger than the ranges proposed by recent climate assessments.
人为硫酸盐气溶胶对云的响应是工业时代气候辐射强迫的最大不确定性来源之一。这种不确定性限制了我们预测平衡气候敏感性（ECS）的能力——即大气 CO2 加倍后全球变暖的平衡状态。在这里，我们使用卫星观测来量化硫酸盐气溶胶和低云之间的关系，同时仔细控制气象条件。然后，我们将这些关系与自 1850 年以来硫酸盐浓度变化的估计值结合起来，以限制相关的辐射强迫。我们估计，人为硫酸盐气溶胶引起的云辐射强迫在全球海洋上约为[Formula: see text] W m（95%置信度）。这一约束意味着 ECS 很可能在 2.9 到 4.5 K 之间（66%置信度）。我们的结果表明，气溶胶强迫的不确定性较小，ECS 可能比最近的气候评估提出的范围更大。
