Although the 8.2 ka event is a well-known globally documented abrupt climate event, its detailed expression in tropical southeastern Africa is poorly constrained. Here we present a high resolution and precisely dated record of the regional hydroclimatic variability between 8.5–7.5 ka BP from a polymorphic speleothem (ABC-1) from northwestern Madagascar. In combination with the exclusive recurrences of calcite layers (indicative of wetter conditions), the distinctly negative excursions in the ABC-1 δ¹⁸O record manifest a wet 8.2 ka event that spanned from 8.230 to 8.053 ka BP. The event is characterized by the replacement of shorter-term (interannual to interdecadal) δ¹⁸O-δ¹³C coherence with the longer-term (multidecadal to centennial) coherence, suggesting a stable and well-developed forest system during the 8.2 ka event. Our data reveal a two-stage structure of the 8.2 ka event, which is superimposed with two brief pluvial episodes in each stage. The widely documented two peaks/troughs during Stage-I suggest rapid propagation of climate signal through atmospheric processes triggered initially by the freshwater forcing, whereas the divergent behaviors of the peaks/troughs in Stage-II in different climate systems may suggest a different forcing.

尽管 8.2 ka 事件是众所周知的全球记录的突变气候事件，但其在热带东南部非洲的详细表达却很少受到限制。在这里，我们提供了来自马达加斯加西北部的多态洞穴（ABC-1）的 8.5-7.5 ka BP 之间区域水文气候变化的高分辨率和精确日期记录。结合方解石层的独家重现（表明更潮湿的条件），ABC-1 δ ¹⁸ O 记录中明显的负偏移表明湿 8.2 ka 事件从 8.230 到 8.053 ka BP。该事件的特点是更换短期（年际到年代际）δ ¹⁸ O-δ ¹³C 与长期（几十年到百年）的一致性，表明在 8.2 ka 事件期间森林系统稳定且发展良好。我们的数据揭示了 8.2 ka 事件的两阶段结构，每个阶段都叠加了两个简短的雨季事件。在第一阶段广泛记录的两个峰/谷表明气候信号通过最初由淡水强迫触发的大气过程快速传播，而第二阶段峰/谷在不同气候系统中的不同行为可能表明不同的强迫。