Equilibrium-line altitudes of the present and Last Glacial Maximum in the eastern Nepal Himalayas and their implications for SW monsoon climate

Abstract

Equilibrium-line altitude (ELA) of a glacier can be an adequate indicator for glaciation and local climate. This study addresses the present ELA in eastern Nepal, in comparison with that of the Last Glacial Maximum (LGM). The present ELA of each glacier was identified by its surface topography using the latest aerial photograph interpretations. ELAs during the LGM were mostly estimated by the maximum elevation of lateral moraines (MELMs). The distinguished higher altitudes of the MELM were selected to estimate the ELAs during the LGM. Latitudinal profiles of the present equilibrium-line show southward gradients, interpreted as a product of the reduction in precipitation from monsoon humid wind blowing into the High Himalayas. Latitudinal ELA profiles of the LGM show the same southward inclination, suggesting that monsoon precipitation is likely to be a ruling resource on glacier nourishment. The eastern Nepal Himalayas, hence, was under summer monsoon environment during the LGM same as present, even if the SW monsoons were weaker.