Observed fingerprint of a weakening Atlantic Ocean overturning circulation
Observed fingerprint of a weakening Atlantic Ocean overturning circulation
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DOI：
10.1038/s41586-018-0006-5
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发表时间：
2018-04-12
期刊：
影响因子：
64.8
通讯作者：
Saba, V.
中科院分区：
文献类型：
--
作者：
Caesar, L.;Rahmstorf, S.;Saba, V.
大西洋纬向翻转环流（AMOC）-北大西洋的洋流系统-对气候有重大影响，但由于缺乏直流测量，其在工业时代的演变知之甚少。在这里，我们提供的证据表明，自世纪中期以来，AMOC减弱了约3 +/- 1 sverdrups（约15%）。这种减弱是由一个特征性的空间和季节性的海面温度“指纹”揭示的-由亚极地大西洋的冷却模式和墨西哥湾流地区的变暖组成-并通过CMIP 5项目的模型模拟的集合进行校准。我们发现这个指纹在一个高分辨率的气候模型中，以应对大气中二氧化碳浓度的增加，并在自19世纪末以来观察到的温度趋势。这种模式可以解释为AMOC的放缓和向北的热量输送减少，以及墨西哥湾流的相关北移。与RAPID项目和其他几项研究最近的直接测量结果进行比较，提供了近年来创纪录的低AMOC值的一致描述。
The Atlantic meridional overturning circulation (AMOC)-a system of ocean currents in the North Atlantic-has a major impact on climate, yet its evolution during the industrial era is poorly known owing to a lack of direct current measurements. Here we provide evidence for a weakening of the AMOC by about 3 +/- 1 sverdrups (around 15 per cent) since the mid-twentieth century. This weakening is revealed by a characteristic spatial and seasonal sea-surface temperature 'fingerprint'-consisting of a pattern of cooling in the subpolar Atlantic Ocean and warming in the Gulf Stream region - and is calibrated through an ensemble of model simulations from the CMIP5 project. We find this fingerprint both in a high-resolution climate model in response to increasing atmospheric carbon dioxide concentrations, and in the temperature trends observed since the late nineteenth century. The pattern can be explained by a slowdown in the AMOC and reduced northward heat transport, as well as an associated northward shift of the Gulf Stream. Comparisons with recent direct measurements from the RAPID project and several other studies provide a consistent depiction of record-low AMOC values in recent years.