Precipitation in the Himalaya is both a vital water resource for millions of people living downstream and a frequent cause of disasters such as floods, landslides, debris flows, and avalanches. Ongoing climate warming is expected to influence the large-scale atmospheric circulation systems that regulate rainfall in the region, including the Indian Summer Monsoon (ISM). However, instrumental precipitation records from the Himalaya are sparse and generally span only the past few decades because of the challenging observational conditions. This limits our understanding of how Himalayan precipitation responds to changing climate.
Lake sediments provide valuable archives of past environmental and climatic conditions. In this project, we reconstruct Himalayan precipitation variability over the past ~1000 years using plant leaf waxes preserved in lake sediments collected along a west-east transect in the central Himalaya. By analysing the hydrogen isotopic composition of these leaf wax compounds (δ2Hwax), we infer changes in precipitation isotopic composition and reconstruct variations in monsoon intensity. By combining records from multiple lakes, this project will provide new insights into how Himalayan precipitation has varied through space and time over the last millennium.
Objectives
The overall aim of this project is to reconstruct Himalayan precipitation variability over the last millennium and improve our understanding of how the Indian Summer Monsoon responds to climate change. Specifically, we aim to:
- Reconstruct Himalayan precipitation variability over the past ~1000 years.
- Identify spatial and temporal patterns in precipitation change across the central Himalaya using records from multiple lakes.
- Improve understanding of how the Indian Summer Monsoon responds to climate change and how these changes affect Himalayan hydroclimate.
Approach
The study focuses on a series of lakes distributed along a west-east transect across the central Himalaya. Sediment cores from these lakes are analysed for plant leaf wax-derived n-alkanes and their hydrogen isotopic composition (δ2Hwax). Because the hydrogen isotopic composition of these compounds reflects that of precipitation, they provide a means to reconstruct past variations in monsoon rainfall. Integrating records from multiple lakes will allow us to assess the magnitude and spatial pattern of Himalayan precipitation changes over the last millennium, providing valuable context for understanding future impacts of climate change on water resources and disaster risk.
This research is part of the EMBRACER project, a ten-year interdisciplinary climate research programme that brings together researchers from Utrecht University, the Royal Netherlands Institute for Sea Research (NIOZ), Vrije Universiteit Amsterdam, Radboud University Nijmegen and Wageningen University & Research. Specifically, the project contributes to EMBRACER SSP7: Impacts of changes in the Indian Summer Monsoon on Himalayan precipitation. Through its focus on past monsoon variability, this research supports EMBRACER’s broader goal of improving our understanding of Earth system feedbacks across timescales relevant to future climate change.
