Longbasaba Glacier recession and contribution to its proglacial lake volume between 1988 and 2018

Junfeng Wei,Te Zhang,Shiyin Liu,Kunpeng Wu,Zongli Jiang,Zhen Zhang,Yong Zhang,Xin Wang

doi:10.1017/jog.2020.119

Abstract

AbstractDuring the last few decades, the lake-terminating glaciers in the Himalaya have receded faster than the land-terminating glaciers as proglacial lakes have exacerbated the mass loss of their host glaciers. Monitoring the impacts of glacier recession and dynamics on lake extent and water volume provides an approach to assess the mass interplay between glaciers and proglacial lakes. We describe the recession of Longbasaba Glacier and estimate the mass wastage and its contribution to the water volume of its proglacial lake. The results show that the glacier area has decreased by 3% during 1988–2018, with a more variable recession prior to 2008 than in the last decade. Longbasaba Lake has expanded by 164% in area and 237% in water volume, primarily as a result of meltwater inflow produced from surface lowering of the glacier. Over the periods 1988–2000 and 2000–18, the mass loss contributed by glacier thinning has decreased from 81 to 61% of the total mass loss, accompanied by a nearly doubled contribution from terminus retreat. With the current rate of retreat, Longbasaba glacier is expected to terminate in its proglacial lake for another four decades. The hazard risk of this lake is expected to continue to increase in the near future because of the projected continued glacier mass loss and related lake expansion.

Highlights

During the last few decades, an average mountain surface air temperature warming rate of 0.3 ± 0.2°C per decade was detected across western North America, Europe and High Mountain Asia, which is higher than the global warming rate of 0.2 ± 0.1°C per decade (IPCC, 2018)
The accuracy of changes in the glacier/lake areas was predominantly controlled by the perimeters of the digital polygons defining the area changes, and it ranged from ±0.017 to ±0.027 km2 during each interval, using the buffer method (Bolch and others, 2010; Guo and others, 2015)
This study investigated the evolution of the recession of Longbasaba Glacier and the related expansion of the proglacial lake over the period of 1988−2018, while the mass contributions from glacier degradation to the water volume of the proglacial lake were assessed

Summary

Introduction

During the last few decades, an average mountain surface air temperature warming rate of 0.3 ± 0.2°C per decade was detected across western North America, Europe and High Mountain Asia, which is higher than the global warming rate of 0.2 ± 0.1°C per decade (IPCC, 2018). Using a combination of in situ station data, gridded datasets from remote-sensing products, and reanalysis datasets, the CMFD data product releases the instantaneous surface (2 m) air temperature and 3 h mean precipitation rate required for land modeling during 1979–2018. These data are available as tiles with a temporal resolution of 3 h and a spatial resolution of 0.1°, and distributed on daily, monthly and yearly scales (Yang and He, 2018). The accuracy of changes in the glacier/lake areas was predominantly controlled by the perimeters of the digital polygons defining the area changes, and it ranged from ±0.017 to ±0.027 km during each interval, using the buffer method (Bolch and others, 2010; Guo and others, 2015)

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Conclusion