An abrupt drop in Northern Hemisphere sea surface temperature around 1970
An abrupt drop in Northern Hemisphere sea surface temperature around 1970
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DOI：
10.1038/nature09394
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发表时间：
2010-09-23
期刊：
影响因子：
64.8
通讯作者：
Jones, Phil D.
中科院分区：
文献类型：
--
作者：
Thompson, David W. J.;Wallace, John M.;Jones, Phil D.
全球平均地表温度在20世纪世纪的趋势并不是单调的：从世纪开始到20世纪40年代，气温上升，在世纪中期略有下降，从20世纪70年代中期开始迅速上升（1）。20世纪气温的变暖-降温-变暖模式通常被解释为温室气体增加导致的长期变暖与20世纪中期对流层硫酸盐气溶胶增加导致的降温（2-4）或数十年来世界海洋气候演变的变化（振荡性多年变率）（2，5）的叠加。在第二次世界大战后的几十年里，对流层中硫酸盐气溶胶的负载被认为对北方和南半球之间的温度趋势差异具有特别重要的作用（2-4）。在这里，我们表明，在世纪中期的温度趋势的半球差异，主要源于快速下降，在北方海表温度约0.3摄氏度之间的1968年和1972年。下降的时间尺度比与对流层气溶胶负荷或以前的特征振荡的几十年变率。这种下降在所有现有的历史海洋表面温度数据集中都很明显，无法追溯到伴随的元数据的变化，也与表面温度测量中的任何已知偏差无关。这种下降并不集中在北方海洋的任何离散区域，但其幅度在北大西洋北方最大。
The twentieth-century trend in global-mean surface temperature was not monotonic: temperatures rose from the start of the century to the 1940s, fell slightly during the middle part of the century, and rose rapidly from the mid-1970s onwards(1). The warming-cooling-warming pattern of twentieth-century temperatures is typically interpreted as the superposition of long-term warming due to increasing greenhouse gases and either cooling due to a mid-twentieth century increase of sulphate aerosols in the troposphere(2-4), or changes in the climate of the world's oceans that evolve over decades (oscillatory multidecadal variability)(2,5). Loadings of sulphate aerosol in the troposphere are thought to have had a particularly important role in the differences in temperature trends between the Northern and Southern hemispheres during the decades following the Second World War(2-4). Here we show that the hemispheric differences in temperature trends in the middle of the twentieth century stem largely from a rapid drop in Northern Hemisphere sea surface temperatures of about 0.3 degrees C between about 1968 and 1972. The timescale of the drop is shorter than that associated with either tropospheric aerosol loadings or previous characterizations of oscillatory multidecadal variability. The drop is evident in all available historical sea surface temperature data sets, is not traceable to changes in the attendant metadata, and is not linked to any known biases in surface temperature measurements. The drop is not concentrated in any discrete region of the Northern Hemisphere oceans, but its amplitude is largest over the northern North Atlantic.