Eisenman Ian, Armour Kyle C
Scripps Institution of Oceanography, University of California San Diego, La Jolla, USA.
Department of Atmospheric Sciences and School of Oceanography, University of Washington, Seattle, USA.
Nat Commun. 2024 Aug 3;15(1):6582. doi: 10.1038/s41467-024-50406-w.
Paleoclimate records have been used to estimate the modern equilibrium climate sensitivity. However, this requires understanding how the feedbacks governing the climate response vary with the climate itself. Here we warm and cool a state-of-the-art climate model to simulate a continuum of climates ranging from a nearly ice-covered Snowball Earth to a nearly ice-free hothouse. We find that the pre-industrial (PI) climate is near a stability optimum: warming leads to a less-stable (more-sensitive) climate, as does cooling of more than 2K. Physically interpreting the results, we find that the decrease in stability for climates colder than the PI occurs mainly due to the albedo and lapse-rate feedbacks, and the decrease in stability for warmer climates occurs mainly due to the cloud feedback. These results imply that paleoclimate records provide a stronger constraint than has been calculated in previous studies, suggesting a reduction in the uncertainty range of the climate sensitivity.
古气候记录已被用于估算现代平衡气候敏感性。然而，这需要了解控制气候响应的反馈如何随气候本身而变化。在此，我们对一个先进的气候模型进行升温与降温操作，以模拟从近乎被冰覆盖的雪球地球到近乎无冰的温室等一系列连续的气候状态。我们发现，工业化前（PI）气候接近一个稳定性最优状态：升温会导致气候稳定性降低（更敏感），降温超过2K时也是如此。从物理角度解释这些结果，我们发现，比PI气候更冷的气候稳定性下降主要是由于反照率和递减率反馈，而更温暖气候的稳定性下降主要是由于云反馈。这些结果意味着，古气候记录提供的约束比以往研究计算的更强，这表明气候敏感性的不确定性范围有所缩小。
