Accelerated glacier mass loss in the largest river and lake source regions of the Tibetan Plateau and its links with local water balance over 1976–2017

Wenfeng Chen,Guoxiong Zheng,Tandong Yao,Guoqing Zhang,Shenghai Li

doi:10.1017/jog.2021.9

Abstract

AbstractVariations in glacier meltwater in the source regions of the Tibetan Plateau's (TP) largest lake (Selin Co) and China's longest river (Yangtze River) regulate the local and downstream water balance under the warming climate. However, the magnitude of their variations over the past four decades is still unknown. Here, we examine long-term changes in glacier mass balance over 1976–2017 using KH-9 and CoSSC-TanDEM-X data. We find that the mean rate of glacier mass loss (GML) has accelerated from −0.21 ± 0.11 m a–1over 1976–2000, to −0.28 ± 0.14 m a–1over 2000–11, and subsequently to −0.48 ± 0.10 m a–1over 2011–17. Changes in temperature and precipitation are the major causes of GML. Over 1976–2017, the contribution of decadal GML to Tuotuohe sub-basin runoff ranges from 4.3 to 8.0%, while its contribution to increased lake volume change in Selin Co and Chibzhang Co-Dorsoidong Co ranges from 3.5 to 16.3% and 19.2 to 21.4%, respectively. The GML of source regions made relatively small contributions to river runoff and lake supply, but plays a vital role when precipitation decreases. The quantitative evaluation of the water balance for the sources of great rivers and lakes over the TP is therefore important for water resource management and hydrological cycle studies.

Highlights

The Tibetan Plateau (TP) has the greatest abundance of glaciers outside the polar regions, with a total area of ∼10 × 104 km2 (RGI Consortium, 2017) and a total ice volume of ∼7 × 103 km3 (Farinotti and others, 2019)
The Geladandong Mountains are located in the Tanggula mountain range in the central TP, an area influenced by both continental climate and the Indian summer monsoon (Tian and others, 2001; Yao and others, 2013)
From 8 January 2017 to 17 April 2017, the glaciers had a net accumulation of 0.24 m, which is similar to the value during the period 17 April 2017 to the 9 May 2017 and indicates a mass-balance gain in this region

Summary

Introduction

The Tibetan Plateau (TP) (mean elevation ∼4000 m a.s.l.) has the greatest abundance of glaciers outside the polar regions, with a total area of ∼10 × 104 km (RGI Consortium, 2017) and a total ice volume of ∼7 × 103 km (Farinotti and others, 2019). Over the past few decades, the climate in the TP has become wetter and warmer (Li and others, 2018a), resulting in glacier mass loss (GML) (Yao and others, 2012b; Brun and others, 2017; Zhou and others, 2018), lake expansion (Lei and others, 2014; Zhang and others, 2019a) and an increase in river runoff (Lutz and others, 2014). These changes are altering the balance of the cryosphere and have significant impacts on the local hydro-climate-ecological cycle, and water supplies (Immerzeel and others, 2010; Lutz and others, 2014; Milner and others, 2017). They feed the Yangtze River, and the two biggest lakes on the TP, Selin Co and Chibzhang Co-Dorsoidong Co (CC-DC) (Fig. 1a)

Results

Discussion

Conclusion