自20世纪70年代以来观测到的全球变暖速率已被认为是，平衡气候敏感性(ECS)和瞬态气候响应(TCR)的强有力的限制，这是全球气候对温室气体作用力响应的关键指标。研究使用CMIP5/6模型表明，变暖和这些气候敏感性指标(限制条件的基础)间的模型间关系，源于模型内瞬态和平衡变暖模式的相似性，产生了控制近期变暖的有效气候敏感性(EffCS)，该值与控制CO2作用力下长期变暖的ECS值相当。
然而，CMIP5/6历史模拟并没有重现观测到的变暖模式。当受观测型态驱动时，即使高ECS模式也产生与观测到的全球变暖速率一致的低EffCS值。CMIP5/6模式无法重现观测到的变暖模式，这导致了最近全球变暖和气候敏感性之间的模式关系存在偏差。纠正这一偏差意味着观测到的变暖与ECS和TCR的大范围一致，它们延伸到比以前认识到的更高的值。
这些发现得到了能量平衡模型模拟和耦合模型(CESM1-CAM5)模拟的证实，这些模拟更好地复制了通过对流层风推动或南极融水通量观测到的模型。由于CMIP5/6模型无法模拟观测到的变暖模式，因此对ECS、TCR和预估基于变暖的全球变暖的限制条件偏低。这些结果强化了最近的发现，即观测到的独特变暖模式减缓了近几十年来全球平均变暖的速度，而这种模式在未来将如何演变是气候预测不确定性的主要来源。
附：英文原文
Title: Sea-surface temperature pattern effects have slowed global warming and biased warming-based constraints on climate sensitivity
Author: Armour, Kyle C., Proistosescu, Cristian, Dong, Yue, Hahn, Lily C., Blanchard-Wrigglesworth, Edward, Pauling, Andrew G., Jnglin Wills, Robert C., Andrews, Timothy, Stuecker, Malte F., Po-Chedley, Stephen, Mitevski, Ivan, Forster, Piers M., Gregory, Jonathan M.
Issue&Volume: 2024-3-11
Abstract: The observed rate of global warming since the 1970s has been proposed as a strong constraint on equilibrium climate sensitivity (ECS) and transient climate response (TCR)—key metrics of the global climate response to greenhouse-gas forcing. Using CMIP5/6 models, we show that the inter-model relationship between warming and these climate sensitivity metrics (the basis for the constraint) arises from a similarity in transient and equilibrium warming patterns within the models, producing an effective climate sensitivity (EffCS) governing recent warming that is comparable to the value of ECS governing long-term warming under CO2 forcing. However, CMIP5/6 historical simulations do not reproduce observed warming patterns. When driven by observed patterns, even high ECS models produce low EffCS values consistent with the observed global warming rate. The inability of CMIP5/6 models to reproduce observed warming patterns thus results in a bias in the modeled relationship between recent global warming and climate sensitivity. Correcting for this bias means that observed warming is consistent with wide ranges of ECS and TCR extending to higher values than previously recognized. These findings are corroborated by energy balance model simulations and coupled model (CESM1-CAM5) simulations that better replicate observed patterns via tropospheric wind nudging or Antarctic meltwater fluxes. Because CMIP5/6 models fail to simulate observed warming patterns, proposed warming-based constraints on ECS, TCR, and projected global warming are biased low. The results reinforce recent findings that the unique pattern of observed warming has slowed global-mean warming over recent decades and that how the pattern will evolve in the future represents a major source of uncertainty in climate projections.
DOI: 10.1073/pnas.2312093121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2312093121