Department of Climate, Atmospheric Science and Physical Oceanography, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
Department of Atmospheric and Oceanic Sciences and Center for Climatic Research, University of Wisconsin-Madison, Madison, WI 53705, USA.
Sci Adv. 2017 Jan 4;3(1):e1601666. doi: 10.1126/sciadv.1601666. eCollection 2017 Jan.
Changes in the Atlantic Meridional Overturning Circulation (AMOC) are moderate in most climate model projections under increasing greenhouse gas forcing. This intermodel consensus may be an artifact of common model biases that favor a stable AMOC. Observationally based freshwater budget analyses suggest that the AMOC is in an unstable regime susceptible for large changes in response to perturbations. By correcting the model biases, we show that the AMOC collapses 300 years after the atmospheric CO concentration is abruptly doubled from the 1990 level. Compared to an uncorrected model, the AMOC collapse brings about large, markedly different climate responses: a prominent cooling over the northern North Atlantic and neighboring areas, sea ice increases over the Greenland-Iceland-Norwegian seas and to the south of Greenland, and a significant southward rain-belt migration over the tropical Atlantic. Our results highlight the need to develop dynamical metrics to constrain models and the importance of reducing model biases in long-term climate projection.
在温室气体增暖强迫下，大多数气候模式预测中大西洋经向翻转环流（AMOC）的变化处于中等程度。这种模式间的一致性可能是共同的模式偏差的产物，这些偏差有利于稳定的 AMOC。基于观测的淡水预算分析表明，AMOC 处于不稳定状态，容易因对干扰的响应而发生大的变化。通过纠正模型偏差，我们表明，在大气 CO 浓度从 1990 年水平突然增加一倍后的 300 年内，AMOC 崩溃。与未经修正的模型相比，AMOC 崩溃带来了大的、明显不同的气候响应：北大西洋北部和邻近地区明显变冷，格陵兰-冰岛-挪威海域和格陵兰岛南部的海冰增加，以及热带大西洋的雨带显著向南迁移。我们的结果强调了需要开发动力指标来约束模型，以及减少模型偏差在长期气候预测中的重要性。
