A modelling approach to reconstruct Little Ice Age climate from remote-sensing glacier observations in southeastern Tibet

Eva Huintjes,Frank Lehmkuhl,Christoph Schneider,David Loibl

doi:10.3189/2016aog71a025

Abstract

AbstractWe use numerical modelling of glacier mass balance combined with recent and past glacier extents to obtain information on Little Ice Age (LIA) climate in southeastern Tibet. We choose two glaciers that have been analysed in a previous study of equilibrium-line altitudes (ELA) and LIA glacier advances with remote-sensing approaches. We apply a physically based surface energy- and mass-balance model that is forced by dynamically downscaled global analysis data. The model is applied to two glacier stages mapped from satellite imagery, modern (1999) and LIA. Precipitation scaling factors (PSF) and air temperature offsets (ATO) are applied to reproduce recent ELA and glacier mass balance (MB) during the LIA. A sensitivity analysis is performed by applying seasonally varying gradients of precipitation and air temperature. The calculated glacier-wide MB estimate for the period 2000–12 is negative for both glaciers (–992±366 kgm–2 a–1 and –1053±258 kgm–2 a–1). Relating recent and LIA PSF/ATO sets suggests a LIA climate with ~8–25% increased precipitation and ~1–2.5°C lower mean air temperature than in the period 2000–12. The results only provide an order of magnitude because deviations in other input parameters are not considered.

Highlights

Temperate glaciers in the eastern Nyainqêntanglha Range, southeastern Tibet, are highly sensitive to climate variations (Yang and others, 2011; Yao and others, 2012)
We focus on the question of whether COSIMA can estimate modern and Little Ice Age (LIA) glacier mass balance (MB) and equilibrium-line altitudes (ELA) when solely based on input from an atmospheric model and remote-sensing data
Air temperature and precipitation from High Asia Refined Analysis (HAR) are varied within realistic limits for two glaciers in the eastern Nyainqêntanglha Range so that the average ELA calculated with COSIMA for 2000–12 agrees with the remote-sensing derived ELA of Loibl and others (2014)

Summary

Introduction

Temperate glaciers in the eastern Nyainqêntanglha Range, southeastern Tibet, are highly sensitive to climate variations (Yang and others, 2011; Yao and others, 2012). This region is of specific interest regarding late-Holocene variability of the monsoonal climate in High Asia (Su and Shi, 2002). Recent remote-sensing studies have shown that glacier mass loss in this area distinctly exceeds the overall average in High Asia (Gardelle and others, 2013a,b; Neckel and others, 2014). The regional LIA maximum glacier advance occurred during the late 17th to early 18th centuries (Bräuning and Lehmkuhl, 1996; Bräuning, 2006; Zhu and others, 2013; Loibl and others, 2015). Knowledge of the palaeoclimatic forcing and glacier dynamics behind these changes is, lacking (Loibl and others, 2015)

Methods

Results

Conclusion