North African greening phases, during which large rivers ran through the Sahara Desert, occurred repeatedly during the Quaternary and are regarded as key periods for the development of past human populations. However, the timing and mechanisms responsible for the reactivation of the presently dormant fluvial systems remain highly uncertain. Here we present hydroclimate changes over the past 160,000 years, reconstructed from analyses of the provenance of terrestrial sediments in a marine sediment record from the Gulf of Sirte (offshore Libya). By combining high-resolution proxy data with transient Earth system model simulations, we are able to identify the various drivers that led to the observed shifts in hydroclimate and landscapes. We show that river runoff occurred during warm interglacial phases of Marine Isotope Stages 1 and 5 due to precession-forced enhancements in the summer and autumn rainfall over the entire watershed, which fed presently dry river systems and intermittent coastal streams. In contrast, shorter-lasting and less-intense humid events during glacial Marine Isotope Stages 3 and 4 were related to autumn and winter precipitation over the Libyan coastal regions driven by Mediterranean storms. Our results reveal large shifts in hydroclimate environments during the last glacial cycle, which probably exerted a strong evolutionary and structural control on past human populations, potentially pacing their dispersal across northern Africa.

大河流经撒哈拉沙漠的北非绿化阶段在第四纪反复出现，被认为是过去人类发展的关键时期。然而，目前处于休眠状态的河流系统重新激活的时间和机制仍然高度不确定。在这里，我们展示了过去 160,000 年的水文气候变化，这些变化是根据对苏尔特湾（利比亚近海）海洋沉积物记录中陆地沉积物来源的分析重建的。通过将高分辨率代理数据与瞬态地球系统模型模拟相结合，我们能够确定导致观测到的水文气候和景观变化的各种驱动因素。我们表明，由于整个流域夏季和秋季降雨的进动强制增强，河流径流发生在海洋同位素 1 期和 5 期的温暖间冰期，这为目前干涸的河流系统和断断续续的沿海溪流提供了食物。相比之下，冰川海洋同位素阶段 3 和 4 期间持续时间较短且强度较低的潮湿事件与地中海风暴驱动的利比亚沿海地区的秋季和冬季降水有关。我们的研究结果揭示了上一个冰河周期期间水文气候环境的巨大变化，这可能对过去的人类种群施加了强大的进化和结构控制，可能会加速它们在北非的扩散。为目前干涸的河流系统和断断续续的沿海溪流提供食物。相比之下，冰川海洋同位素阶段 3 和 4 期间持续时间较短且强度较低的潮湿事件与地中海风暴驱动的利比亚沿海地区的秋季和冬季降水有关。我们的研究结果揭示了上一个冰河周期期间水文气候环境的巨大变化，这可能对过去的人类种群施加了强大的进化和结构控制，可能会加速它们在北非的扩散。为目前干涸的河流系统和断断续续的沿海溪流提供食物。相比之下，冰川海洋同位素阶段 3 和 4 期间持续时间较短且强度较低的潮湿事件与地中海风暴驱动的利比亚沿海地区的秋季和冬季降水有关。我们的研究结果揭示了上一个冰河周期期间水文气候环境的巨大变化，这可能对过去的人类种群施加了强大的进化和结构控制，可能会加速它们在北非的扩散。