NOAA/WDS Paleoclimatology - Lake Victoria 14,000 Year Diatom Correspondence Analysis

East Africa's enormous Lake Victoria dried out at the close of the last glacial, but the precise timing and origin of that drying event have not been clarified, largely because of uncertainty regarding core stratigraphy and ancient carbon effects on 14C dates from the lake. New dates and re-examination of evidence from widely distributed cores shows that desiccation occurred some time between 15 900 and 14 200 calendar years BP, and perhaps also ca. 18-17 kyr BP. These lake level minima were briefer than has been previously suggested and were synchronous with pronounced global climate disruptions including North Atlantic ice-rafting Heinrich event 1. Less severe declines occurred during the Older and Younger Dryas intervals. Dansgaard-Oeschger type cooling cycles registered in the GISP2 ice core record tracked major lake level regressions in East Africa and weakenings of Afro-Asian monsoons during the late Quaternary, possibly linking the desiccation of Lake Victoria to century-scale reductions in solar radiation output.

东非巨型湖泊维多利亚湖（Lake Victoria）在上一次冰期结束阶段曾彻底干涸，但该干涸事件的精确发生时间与成因尚未明确，这主要源于湖底岩芯地层学（core stratigraphy）研究的不确定性，以及古碳效应对湖泊沉积物碳十四测年（14C dates）结果的干扰。通过新获取的测年数据与对广泛分布的岩芯证据的重新审视，研究表明该湖的干涸事件发生于距今15900至14200日历年间，或许还存在约18-17 kyr BP的干涸阶段。此次湖平面最低水位的持续时长较此前学界的推测更短，且与包括北大西洋浮冰海因里希事件1（Heinrich event 1）在内的显著全球气候扰动同步发生。在老仙女木期（Older Dryas）与新仙女木期（Younger Dryas）时段，湖平面的下降幅度相对平缓。格陵兰冰芯计划2（GISP2，Greenland Ice Sheet Project 2）冰芯记录中所记载的丹斯果-奥什格尔（Dansgaard-Oeschger）型冷却周期，与晚第四纪（late Quaternary）时期东非的湖平面大幅退缩以及亚非季风（Afro-Asian monsoons）的减弱存在对应关系，这一关联或许将维多利亚湖的干涸与百年尺度的太阳辐射输出减少联系起来。