| Dang Shaohua,Yu Kefu,Tao Shichen,Han Tao,Zhang Huiling,Jiang Wei. 2020. El Niño/Southern Oscillation during the 4.2 ka event recorded by growth rates of corals from the North South China Sea. Acta Oceanologica Sinica, 39(1):110－117 |
| El Niño/Southern Oscillation during the 4.2 ka event recorded by growth rates of corals from the North South China Sea |
| 南海北部珊瑚生长率对4.2 ka气候事件的记录 |
| Received:May 16, 2019 |
| DOI：10.1007/s13131-019-1520-5 |
| Key words:4.2 ka event ENSO variability SSTA coral growth rate Xisha Islands |
| 中文关键词: 西沙海域 珊瑚生长率 SSTA 4.2ka气候事件 ENSO活动 |
| 基金项目:The National Natural Science Foundation of China under contract No. 91428203; the Guangxi Scientific Projects under contract Nos AD17129063 and AA17204074; the Bagui Fellowship from Guangxi of China. |
| Author Name | Affiliation | E-mail | | Dang Shaohua | Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning 530004, China
Coral Reef Research Center of China, Guangxi University, Nanning 530004, China
School of Marine Sciences, Guangxi University, Nanning 530004, China | | | Yu Kefu | Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning 530004, China
Coral Reef Research Center of China, Guangxi University, Nanning 530004, China
School of Marine Sciences, Guangxi University, Nanning 530004, China | kefuyu@scsio.ac.cn | | Tao Shichen | South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China | | | Han Tao | South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China | | | Zhang Huiling | College of Ocean Engineering, Guangdong Ocean University, Zhanjiang 524088, China | | | Jiang Wei | Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning 530004, China
Coral Reef Research Center of China, Guangxi University, Nanning 530004, China
School of Marine Sciences, Guangxi University, Nanning 530004, China | |
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| Abstract: |
| The 4.2 ka event that occurred during the period from 4 500-3 900 a BP was characterized by cold and dry climates and resulted in the collapse of civilizations around the world. The cause of this climatic event, however, has been under debate. We collected four corals (Porites lutea) from Yongxing Island, Xisha Islands, South China Sea, dated them with the U-series method, and measured the annual coral growth rates using X-ray technology. The dating results showed that the coral growth ages were from 4 500-3 900 a BP, which coincide well with the period of the 4.2 ka event. We then reconstructed annual sea surface temperature anomaly (SSTA) variations based on the coral growth rates. The growth rate-based SSTA results showed that the interdecadal SSTA from 4 500-3 900 a BP was lower than that during modern times (1961-2008 AD). A spectral analysis showed that the SSTA variations from 4 500-3 900 a BP were under the influence of El Niño-Southern Oscillation (ENSO) activities. From 4 500-4 100 a BP, the climate exhibited La Niña-like conditions with weak ENSO intensity and relatively stable and lower SSTA amplitudes. From 4 100-3 900 a BP, the climate underwent a complicated period of ENSO variability and showed alternating El Niño-or La Niña-like conditions at interdecadal time scales and large SSTA amplitudes. We speculate that during the early and middle stages of the 4.2 ka event, the cold climate caused by weak ENSO activities largely weakened social productivity. Then, during the end stages of the 4.2 ka event, the repeated fluctuations in the ENSO intensity caused frequent extreme weather events, resulting in the collapse of civilizations worldwide. Thus, the new evidence obtained from our coral records suggests that the 4.2 ka event as well as the related collapse of civilizations were very likely driven by ENSO variability. |
| 中文摘要: |
| 4.2 ka气候事件是指4500-3800a BP期间发生在全球的一次气候异常干冷事件，该事件导致了诸多人类文明的崩溃，但是关于该气候事件的原因仍存在较大的争议。本文基于采自西沙群岛永兴岛的4块澄黄滨珊瑚并经高精度铀系年代测定，得出其生长年代范围介于4500-3900a BP之间，与4.2 ka气候事件的时间范围相吻合；再依据其骨骼X光片所显示的生长率重建了该气候事件期间西沙海域的气候变化。重建结果显示，在4500-3900a BP期间西沙海域的海水表层相对温度（SSTA）变化在年代际尺度上低于近40年以来（1961-2008年）。频谱分析的结果表明西沙海域的SSTA主要受到4.2ka气候事件期间ENSO强度变化的控制。在4500-4100a BP期间，ENSO相对活动强度大幅减弱，气候在大部分时间内呈现出La Nina态，同时SSTA在年代际尺度上的波动较低；在4100-3900a BP期间，随着ENSO活动增强其变化模式也愈加复杂，表现为年代际尺度上La Nina态和El Nino态气候的交替控制，SSTA在年代际尺度上的波动较大。4.2ka气候事件前期因ENSO活动减弱导致的降温削弱了当时段人类的生产力，而末期ENSO活动强度的反复波动可能导致当时极端气候灾害频发，人类对自然环境的耐受度几近崩溃并最终驱动了这一时段世界各地大量农业文明的衰落。因此来自珊瑚记录的证据表明4.2ka气候事件及其导致的古文明衰落极有可能和当时的ENSO活动有关。 |
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