The 4.2 ka event was the most abrupt climatic event during the transition between the middle and late Holocene. It had a profound influence on the regional ecological environment and human cultural development and was characterized by the rapid onset of aridification in the mid- and low-latitudes regions of the Northern Hemisphere. However, the nature, structure and spatial expression of the 4.2 ka event in the Asian summer monsoon (ASM) region are controversial. We produced a detailed record of regional vegetation change during the interval of 5000–3500 cal yr BP, based on a high-resolution (~10 yr) pollen record from Yazihai Lake, on the margin of the region influenced by the ASM. The results indicate that an interval of climatic aridification, correlative with the 4.2 ka event, occurred during 4340–3880 cal yr BP, with the duration of 460 yr. However, the structure of the event is relatively complex, with arid conditions during 4340–4280 cal yr BP, wetter conditions during 4280–4150 cal yr BP, and arid conditions during 4150–3880 cal yr BP. A comprehensive comparison of the results from Yazihai Lake with existing high-resolution and well-dated paleoclimate records from the ASM region show that the precipitation response to the 4.2 ka event was spatially and temporally synchronous, with a consistent of timing, duration, and structural characteristics in the northern and southwestern parts of the ASM region; whereas the opposite response occurred in the southeastern part, where the precipitation increased. We suggest that the driving mechanism of the 4.2 ka event was related to sea-air interactions in the low-latitude region. Sea surface temperature (SST) anomalies and the variation of the El Niño-Southern Oscillation (ENSO) in the tropical Pacific region was the main cause, which led to a weaker ASM circulation and a southward shift of the monsoon rainbelt. These changes resulted in decreased monsoonal precipitation and a dry climate in the northern and southwestern parts of the ASM region, but to increased precipitation in the southeastern part.

4.2 ka事件是全新世中晚期过渡时期最突然的气候事件。它对区域生态环境和人类文化发展产生了深远的影响，其特点是北半球中低纬度地区干旱化迅速发生。然而，亚洲夏季风（ASM）地区 4.2 ka 事件的性质、结构和空间表现存在争议。我们基于受 ASM 影响的区域边缘的鸭子海的高分辨率（~10 年）花粉记录，制作了 5000-3500 cal yr BP 区间内的区域植被变化的详细记录。结果表明，与 4.2 ka 事件相关的气候干旱化间隔发生在 4340-3880 cal yr BP 期间，持续时间为 460 年。然而，该事件的结构相对复杂，4340-4280 cal yr BP期间为干旱条件，4280-4150 cal yr BP期间为较潮湿条件，4150-3880 cal yr BP期间为干旱条件。鸭子海的结果与ASM地区现有的高分辨率和年代久远的古气候记录的综合比较表明，对4.2 ka事件的降水响应在时空上是同步的，在时间、持续时间和结构上是一致的。 ASM 地区北部和西南部的特征；而东南部则相反，降水增加。我们认为4.2 ka事件的驱动机制与低纬度地区的海气相互作用有关。热带太平洋地区海表温度（SST）异常和厄尔尼诺-南方涛动（ENSO）变化是导致ASM环流减弱和季风雨带南移的主要原因。这些变化导致ASM地区北部和西南部季风降水减少，气候干燥，但东南部降水增加。