研究全新世以来的气候变化特征是当今世界范围内古气候研究的重点和热点.位于亚洲东南部的中国西南地区地貌类型复杂,其气候变化不仅受全球性气候因素驱动,也显著受其他区域性因素的影响,更加具有复杂性.在对中国西南地区全新世以来孢粉重建古气候相关研究整合分析的基础上,归纳总结该区百年时间尺度上全新世植被演替和气候变化的主要特征.主要通过综述西南地区典型地理单元全新世以来的气候演替特征,进而围绕区域性和全球性的气候突变事件进行比较研究,结果表明西南地区全新世以来总体呈现湿润的气候特征,即早期(11.5-8 ka BP)气候从干冷向暖湿转变,中期(8-3.5 ka BP)温暖湿润,晚期(3.5 ka BP至今)气候向减湿方向发展;该区气候对于8.2 ka BP冷事件的响应不如5.5 ka BP冷事件明显,表明该区具有相对独特的区域性气候特征.最后鉴于西南地区全新世古气候研究相对滞后的现状,指出未来不仅需要加快区域孢粉数据集成,也要积极引入新方法、新指标进行对比验证,从而实现对区域气候变化的深入理解.
英文摘要:
Due to present-day global climate change,a considerable effort has been made over the last few decades to provide reliable estimates of paleoclimate changes,particularly those occurring since the Holocene.Southwestern China is located in southeastern Asia,and contains landscapes of diverse and complex geomorphic types.Its climate is not only driven by global climate factors,but is also significantly affected by other regional factors.To infer the past climate changes that occurred in southwestern China and to better understand the mechanisms that drove those changes,we analyzed the vegetation succession and climatic changes in southwestern China since the Holocene based on palynological reconstructions and paleoclimate studies.The collections held by regional pollen databases and several well-dated sequences offered exceptional opportunities to investigate the past temperature and rainfall distributions in southwestern China during the Holocene,as well as their variations through time and space.The results of our analyses revealed that the paleoclimate of southwestern China could be classified into three stages.The initial stage was from 11.5 to 8 ka BP,during which the climate changed from cold-dry to warm-humid.The second stage (8-3.5 ka BP) was characterized by a relatively warm and humid climate.In the late Holocene(3.5 ka BP to present),the climate and environment became increasingly arid.The past climatic fluctuations we detected in southwestern China were consistent with global climate changes over the same periods.Notably,the climate of southwestern China responded more obviously to the 5.5 ka BP cold event than to the 8.2 ka BP cold event,indicating a typical characteristic of the regional climate.Future work will focus on integrating pollen data from multiple regions and exploring multiple climatic indicators,including the introduction of new methods,for the comparative verification of results.This will assist in improving our understanding of future climate change.