Editorial preface to special issue: Speleothem records of multi-scale interhemispheric summer monsoon variability

In order to enhance our understanding of the late Quaternary climate and environmental changes, as well as their driving mechanisms in monsoon regions on both sides of the Equator, we present a comprehensive suite of 27 publications in this Virtual Special Issue (VSI). These publications can be broadly categorized into three themes: (1) Holocene millennial to decadal timescales climate and environmental changes; (2) Millennial-timescale climate and environmental changes during the last Glacial period; (3) Millennial to centennial variability of monsoon during the penultimate glacial and interglacial periods. Besides the traditional oxygen and carbon isotope proxies, several studies in this VSI have employed new proxies (trace element ratios, Sr isotopes) to reconstruct hydroclimate variability, representing a significant development in speleothem-based research. The study area covered by publications includes the Asian, South American, and African monsoon regions, providing a comprehensive overview of the current state of knowledge of palaeomonsoon research.