Elevated equilibrium line altitude over High Mountain Asia during the Last Interglacial

Abstract

High Mountain Asia (HMA) was experiencing rapid climate change and significant glacier shrinkage in recent three decades, which has profound environmental and socioeconomic impacts on Asia. To better decipher the climate-glacier interaction, we examine climate change and the associated response of the Equilibrium Line Altitude (ELA) over HMA during the Last Interglacial (LIG), often viewed as a potential analogue for future warming world. Based on the bias-corrected model outputs from the Paleoclimate Modeling Intercomparison Project Phase 4, we illustrate an overall warmer/wetter state over HMA in summer but colder/drier conditions in winter during the LIG relative to the preindustrial. In response to the modeled climate change, the ELA rises by ∼466 ± 124 m on average across HMA during the LIG relative to the preindustrial, with more intense increase in the northern parts. Moreover, our sensitivity analysis shows that air temperature change dominates the variation of ELA during the LIG, and climate change during the summer season plays the most important role compared with the other seasons. Additionally, we demonstrate that the modeled ELA change could be largely biased if the seasonality effect is not considered. Despite the lack of glacier deposits/sediments for the LIG, the elevated ELA is in accordance with the reconstructed summer warming and expanded ancient lakes. Our results may improve the understanding of glacier behavior over HMA during the LIG and shed light on glacier response to future warming.