近日，美国华盛顿大学David B. Bonan课题组揭示了观测限制暗示未来大西洋经向翻转环流减弱有限。这一研究成果于2025年5月29日发表在《自然—地球科学》杂志上。
21世纪大西洋经向翻转环流（AMOC）减弱的程度因气候模型而异，一些模型预测会大幅减弱。研究组表明，通过使用将AMOC强度与经向密度差和大西洋翻转深度联系起来的热风表达式，可以大大降低这种不确定性。该表达式捕捉了AMOC弱化中的模型间传播，其中大部分传播来自翻转深度变化。翻转深度也建立了当前和未来AMOC实力之间的关键联系。
具有更强和更深的现今翻转的气候模型往往预测在变暖的情况下会有更大的减弱和变浅，因为现今的北大西洋分层较少，允许更深入地渗透表面浮力通量变化，深度处的密度变化更大，从而导致更大的AMOC减弱。通过结合观测约束，研究组得出结论，到本世纪末AMOC将经历约3-6 Sv（约18-43%）的有限减弱 ，无论排放情景如何。这些结果表明，21世纪AMOC减弱的不确定性和预测AMOC大幅减弱的倾向主要归因于气候模型在准确模拟当今海洋分层方面的偏差。
附：英文原文
Title: Observational constraints imply limited future Atlantic meridional overturning circulation weakening
Author: Bonan, David B., Thompson, Andrew F., Schneider, Tapio, Zanna, Laure, Armour, Kyle C., Sun, Shantong
Issue&Volume: 2025-05-29
Abstract: The degree to which the Atlantic meridional overturning circulation (AMOC) weakens over the twenty-first century varies widely across climate models, with some predicting substantial weakening. Here we show that this uncertainty can be greatly reduced by using a thermal-wind expression that relates the AMOC strength to the meridional density difference and the overturning depth in the Atlantic. This expression captures the intermodel spread in AMOC weakening, with most of the spread arising from overturning depth changes. The overturning depth also establishes a crucial link between the present-day and future AMOC strength. Climate models with a stronger and deeper present-day overturning tend to predict larger weakening and shoaling under warming because the present-day North Atlantic is less stratified, allowing for a deeper penetration of surface buoyancy flux changes, larger density changes at depth and, consequently, larger AMOC weakening. By incorporating observational constraints, we conclude that the AMOC will experience limited weakening of about 3–6Sv (about 18–43%) by the end of this century, regardless of emissions scenario. These results indicate that the uncertainty in twenty-first-century AMOC weakening and the propensity to predict substantial AMOC weakening can be attributed primarily to climate model biases in accurately simulating the present-day ocean stratification.
DOI: 10.1038/s41561-025-01709-0
Source: https://www.nature.com/articles/s41561-025-01709-0