Department of Geological Sciences and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden.
School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa.
PLoS One. 2021 Mar 17;16(3):e0246821. doi: 10.1371/journal.pone.0246821. eCollection 2021.
Southern Africa sits at the junction of tropical and temperate systems, leading to the formation of seasonal precipitation zones. Understanding late Quaternary paleoclimatic change in this vulnerable region is hampered by a lack of available, reliably-dated records. Here we present a sequence from a well-stratified sedimentary infill occupying a lower slope basin which covers 17,060 to 13,400 cal yr BP with the aim to reconstruct paleoclimatic variability in the high Drakensberg during the Late Glacial. We use a combination of pollen, total organic carbon and nitrogen, δ13C, Fourier transform infrared spectroscopy attenuated total reflectance (FTIR-ATR) spectral and elemental data on contiguous samples with high temporal resolution (10 to 80 years per sample). Our data support a relatively humid environment with considerable cold season precipitation during what might have been the final stage of niche-glaciation on the adjoining southern aspects around 17,000 cal yr BP. Then, after an initial warmer and drier period starting ~15,600 cal yr BP, we identify a return to colder and drier conditions with more winter precipitation starting ~14,380 cal yr BP, which represents the first local evidence for the Antarctic Cold Reversal (ACR) in this region. On decadal to centennial timescales, the Late Glacial period was one marked by considerable climatic fluctuation and bi-directional environmental change, which has not been identified in previous studies for this region. Our study shows complex changes in both moisture and thermal conditions providing a more nuanced picture of the Late Glacial for the high Drakensburg.
南非位于热带和温带系统的交界处,导致季节性降水带的形成。由于缺乏可用的、可靠日期的记录,理解这个脆弱地区的晚第四纪古气候变化受到了阻碍。在这里,我们展示了一个来自一个地层良好的沉积填充序列,该序列占据了一个下部斜坡盆地,覆盖了 17060 到 13400 年 cal yr BP,目的是重建高德拉肯斯堡在晚冰期的古气候变化。我们使用花粉、总有机碳和氮、δ13C、傅里叶变换红外光谱衰减全反射(FTIR-ATR)光谱和元素数据的组合,对具有高时间分辨率(10 到 80 年/样品)的连续样品进行分析。我们的数据支持了一个相对湿润的环境,在大约 17000 年 cal yr BP 左右,可能是毗邻南部地区最后阶段的生态冰川作用的末期,有相当多的冷季降水。然后,在大约 15600 年 cal yr BP 开始的一个初始温暖和干燥时期之后,我们发现从大约 14380 年 cal yr BP 开始,气候又回到了更冷和更干燥的条件,冬季降水更多,这代表了该地区首次出现南极冷反转(ACR)的本地证据。在数十年到百年的时间尺度上,晚冰期的特点是气候波动和环境变化的双向性,这在该地区以前的研究中没有被发现。我们的研究表明,湿度和温度条件都发生了复杂的变化,为高德拉肯斯堡的晚冰期提供了一个更细致入微的画面。