Accelerated lake expansion on the Tibetan Plateau in the 2000s: Induced by glacial melting or other processes?

Abstract

Alpine lakes on the Tibetan Plateau are minimally disturbed by human activities and are sensitive indicators of climate variability. Accelerated lake expansion in the 2000s has been confirmed by both dramatic lake-area increases (for 312 lakes larger than 10 km 2 ) derived from optical images, and rapid water-level rises (for 117 lakes with water-level data) measured by satellite altimetry. However, the underlying climate causes remain unclear. This paper analyzes the relationship between the water-level changes of lakes on the plateau and the potential driving factors, such as the glacier meltwater supply and a dependency on precipitation and runoff over the whole plateau and in each zone. The results show that the rates of change of non-glacier-fed lakes in the 2000s were as high as those of glacier-fed lakes across the whole plateau and the lake-level changes were closely associated with the lake supply coefficients (the basin/lake area ratio). The lake variations agreed well with the spatial pattern of precipitation changes. However, in different zones, especially at around 33 N north of the plateau, glacier-fed lakes did exhibit faster lake level increases than no-glacier-fed lakes, indicating that the presence of a glacier meltwater supply augmented the precipitation-driven lake expansions in these areas. Despite the absence of quantitative modeling due to limited data availability, this study provides qualitative support that the lake expansions on the Tibetan Plateau in the 2000s have been driven primarily by changes in precipitation and evapotranspiration and not solely by the effect of glacier wastage.

Combined ICESat and CryoSat-2 Altimetry for Accessing Water Level Dynamics of Tibetan Lakes over 2003–2014

“…Some recent research indicate that increasing precipitation may be the main driving mechanism of lake growths at the plateau scale [3,6]. As analyzed in Section 3.2, most of examined lakes over Hol Xil showed accelerated growths while rising rates of lake levels along the Gangdise Mountains decreased.…”

“…The reliability of ICESat altimetry data used for investigating water level changes of Tibetan lakes has been confirmed by comparing with hydrological station data, radar altimetry, and lake area data derived from optical images [1,2,7,21,22]. We obtained the ICESat Level-2 altimetry data (Release-33) during 2003-2009 from National Snow and Ice Data Center [3,10].…”

“…The main driving force behind dramatic lake dynamics over the TP has been under debate recently [3,6,7,[30][31][32][33][34]. One viewpoint supports that increasing glacial meltwater is the primary factor of rapid lake expansions in the Tibetan Plateau as most mountain glaciers showed obvious retreats during the past decades.…”

“…Tibetan lake level changes during 2003-2009 have been investigated in some earlier studies based on ICESat data [1,3,21]. In this study we focus on examining and comparing the lake level changes during the two observation periods 2003-2009 (P1) and 2010-2014 (P2).…”

“…Recent research reveals dramatic changes in water level and mass budgets of Tibetan lakes in the early twenty-first century [1][2][3][4], indicating a sharp alteration existing in mass balance of Asian "water tower" [2,4,5] and an evident signal of climate dynamics [3,[6][7][8][9]. These findings greatly depend on the lake elevation measurements by the Ice, Cloud, and land Elevation satellite (ICESat), as long-term in situ hydrological observations at the plateau scale are unavailable due to the remoteness and broad coverage of the Tibetan Plateau (TP).…”