Southeast Asian ecological dependency on Tibetan Plateau streamflow over the last millennium

Our understanding of historical ranges and future changes in water availability for much of southeast Asia is, however, limited by short observational records and complex environmental factors. Here, we present annually resolved and absolutely dated tree ring-based streamflow reconstructions for the Mekong, Salween and Yarlung Tsangpo Rivers since 1000 CE, which are supplemented by corresponding model projections until 2100 CE.

We show a significant positive correlation between streamflow and dry season vegetation indices over the Indochinese Peninsula, revealing the importance of the Tibetan Water Tower for the functioning and productivity of ecological and societal systems in southeast Asia. The streamflow variability is associated with low-frequency sea-surface temperature variability in the North Atlantic and North Pacific. We find that streamflow extremes coincide with distinct shifts in local populations that occurred during medieval times, including the occupation and subsequent collapse of Angkor Wat from the 11th to the 16th century.