Orbital precession modulates interannual rainfall variability, as recorded in an Early Pleistocene speleothem
Orbital precession modulates interannual rainfall variability, as recorded in an Early Pleistocene speleothem
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DOI：
10.1130/g45019.1
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发表时间：
2018-07
期刊：
影响因子：
5.8
通讯作者：
P. Hopley;G. Weedon;C. Brierley;C. Thrasivoulou;A. Herries;Ada Dinckal;D. Richards;D. Niţă;R. Parrish;N. Roberts;D. Sahy;Claire L. Smith
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作者：
P. Hopley;G. Weedon;C. Brierley;C. Thrasivoulou;A. Herries;Ada Dinckal;D. Richards;D. Niţă;R. Parrish;N. Roberts;D. Sahy;Claire L. Smith
非洲降雨的年际变化影响当地和全球社区，但其过去的行为和未来气候预测的响应知之甚少。这主要是由于短仪器记录和缺乏长期的高分辨率古气候代用记录。在这里，我们提出了一个每年解决91,000年的早更新世水文气候记录从早期人类轴承Makapansgat谷，南非。洞穴沉积物年带厚度的变化主要是由四个连续的轨道周期与强大的千年尺度的周期性岁差。年际变率（2.0-6.5年振荡）的频率不系统地改变，但其振幅调制的轨道强迫。这些长期的年际变化的特点再现与瞬态气候模式模拟的水平衡，南非从晚更新世到最近。基于这些结果，我们认为，在南部非洲降雨的年际变化的频率很可能是稳定的人为变暖下，但每年的变化的大小可能会增加。我们看到，在1.8 Ma和1.7 Ma之间的年际气候变率的幅度的轨道强迫增加与阿舍利石器技术的第一个证据相一致。
Interannual variability of African rainfall impacts local and global communities, but its past behavior and response in future climate projections are poorly understood. This is primarily due to short instrumental records and a lack of long high-resolution palaeoclimate proxy records. Here we present an annually resolved 91,000 year Early Pleistocene record of hydroclimate from the early hominin-bearing Makapansgat Valley, South Africa. Changes in speleothem annual band thickness are dominated by precession over four consecutive orbital cycles with strong millennial-scale periodicity. The frequency of interannual variability (2.0–6.5 yr oscillations) does not change systematically, yet its amplitude is modulated by the orbital forcing. These long-term characteristics of interannual variability are reproduced with transient climate model simulations of water balance for South Africa from the Late Pleistocene to Recent. Based on these results, we suggest that the frequency of interannual variations in southern African rainfall is likely to be stable under anthropogenic warming, but that the size of year-to-year variations may increase. We see an orbitally forced increase in the amplitude of interannual climate variability between 1.8 Ma and 1.7 Ma coincident with the first evidence for the Acheulean stone tool technology.