近日，美国华盛顿大学Vincent T. Cooper团队报道了古气候模式效应有助于限制气候敏感性和21世纪的变暖。相关论文发表在2026年1月22日出版的《美国科学院院刊》杂志上。

古气候为研究过去气候变化提供了范例，有助于估算温室气体排放导致的现代气候变暖程度，即地球气候敏感性。然而，利用古气候证据推断气候敏感性时，必须考量过去与当代气候变化的差异。与温室气体排放所致近期变暖最为接近的古气候类比对象是上新世（距今530万至260万年），该温暖时期大气二氧化碳浓度与当前水平相当。最新重建数据显示，上新世气温较既往认知高出1°C，意味着更高的气候敏感性——这一结论亦得到末次盛冰期（距今1.9万至2.3万年）重建结果的支持，该研究显示二氧化碳浓度降低会导致更显著降温。但古气候温度变化的大尺度模式与现代预测存在显著差异。

气候反馈与敏感性取决于温度分布模式，因此利用古气候约束现代气候敏感性时必须考量此类"模式效应"。研究组通过数据同化重建与大气环流模式相结合，揭示地球气候对上新世强迫的响应强于现代二氧化碳强迫。上新世冰盖、地形与植被改变海洋变暖格局，并触发不稳定的云反馈机制；末次盛冰期反馈同样因北美冰盖作用而增强。纳入古气候模式效应修正后，现代气候敏感性的最优估计值（中位数）为2.8°C，66%置信区间为2.4-3.4°C（90%置信区间：2.1-4.0°C），这将显著降低21世纪气候变暖预测的不确定性。

附：英文原文

Title: Paleoclimate pattern effects help constrain climate sensitivity and 21st-century warming

Author: Cooper, Vincent T., Armour, Kyle C., Hakim, Gregory J., Tierney, Jessica E., Burls, Natalie J., Proistosescu, Cristian, Andrews, Timothy, Dong, Wenhao, Dvorak, Michelle T., Feng, Ran, Osman, Matthew B., Dong, Yue

Issue&Volume: 2026-1-22

Abstract: Paleoclimates provide examples of past climate change that inform estimates of modern warming from greenhouse-gas emissions, known as Earth’s climate sensitivity. However, differences between past and present climate change must be accounted for when inferring climate sensitivity from paleoclimate evidence. The closest paleoclimate analog to near-term warming from greenhouse-gas emissions is the Pliocene (5.3 to 2.6 Ma), a warm epoch with atmospheric CO2 concentrations similar to today. Recent reconstructions indicate the Pliocene was 1 °C warmer than previously thought, implying higher climate sensitivity, which is also supported by recent reconstructions showing more cooling with reduced CO2 at the Last Glacial Maximum (LGM; 19 to 23 thousand years ago). However, large-scale patterns of paleoclimate temperature change differ strongly from modern projections. Climate feedbacks and sensitivity depend on temperature patterns, and such “pattern effects” must be accounted for when using paleoclimates to constrain modern climate sensitivity. Here we combine data-assimilation reconstructions with atmospheric general circulation models to show Earth’s climate is more sensitive to Pliocene forcing than modern CO2 forcing. Pliocene ice sheets, topography, and vegetation alter patterns of ocean warming and excite destabilizing cloud feedbacks, and LGM feedbacks are similarly amplified by the North American ice sheets. Accounting for paleoclimate pattern effects produces a best estimate (median) for modern climate sensitivity of 2.8 °C and 66% CI of 2.4 to 3.4 °C (90% CI: 2.1 to 4.0 °C), substantially reducing uncertainty in projections of 21st-century warming.

DOI: 10.1073/pnas.2511370123

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2511370123