The westerlies-monsoon interaction shaped asymmetric lake expansions over the Tibetan Plateau in warming periods

Abstract

Modelling studies and recent observations suggest that the westerlies-monsoon interactions (WMI) have led to a spatial imbalance in lake expansions across the Tibetan Plateau (TP) during the past decades under anthropogenic warming. However, whether such imbalance reflects a short-term phenomenon or a long-term climatic trend remains unclear. Here, we present a 240,000-year lake level reconstruction from the inner TP to examine the extent to which WMI also operated for previous interglacials, natural warm regimes with large-scale climatic boundary changes. Results suggest pronounced lake expansions accompanied by enhanced rainfall during the recent three interglacials, marine isotope stage (MIS) 7, 5, and 1, notably with varying amplitudes of “V” shape (MIS 5 < MIS 7 or MIS 1). This lake expansion pattern is coherent with North Hemisphere ice volume (NHIV) variations among these interglacials. Model simulation further suggests more NHIV may impact WMI by modulating westerlies’ position, causing rainfall increase and lake expansion over the inner TP relative to its marginal areas. Our findings confirm that the projected importance of WMI to drive the spatial heterogeneity of hydroclimate changes has been maintained during the past natural warm periods. We thus predict that the climate warming and NHIV decreasing will further amplify the spatial imbalance of lake expansions across the TP, with more pronounced lake expansions in the north relative to the south.