Research

A bigger picture of how the Tibetan lakes change over the past decade revealed by CryoSat‐2 altimetry

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Abstract

Tibetan lakes are an effective indicator of climate change as they are highly sensitive to and directly affected by climate change. The past decade has seen the 7 warmest years on record globally. Such observations have prompted questions about lake changes over the Tibetan Plateau. The dense coverage of the CryoSat‐2 altimeter reveals large‐scale patterns in this climate change signal. We investigate lake level variations of more than 200 lakes using altimetry observations from CryoSat‐2 during the period 2010 to 2019. Combined with GRACE/GRACE‐FO, we evaluate the water storage change of lakes and terrestrial water storage (TWS). We find that most studied lakes generally went through three phases of change, i.e. rising‐hiatus/decline‐rising, albeit lakes in the north Tibetan Plateau show higher rising rates. Results also show that lake levels are widely affected by the 2015/16 El Niño event across the entire inner plateau via reduced precipitation. Above normal precipitation during 2016‐2018, resulted in a sharp rise of ~1.22 m on average, accounting for 56% of the decadal lake level rise (mean/median: 2.19/1.85 m). TWS in the Inner Tibetan Plateau accumulated a net gain of 70.5 km3, which is dominated by the net gain of lake water storage (ca. 63.3 km3). The interannual TWS variation is found to be associated mainly with precipitation. In particular, extreme conditions such as the 2015/16 El Niño, had a profound negative impact on the TWS. The findings in this study shed new light on the response of Tibetan lakes to recent decadal environmental changes.