What Controls Lake Contraction and Then Expansion in Tibetan Plateau's Endorheic Basin Over the Past Half Century?

The evolutions of climate‐sensitive lakes on the Tibetan Plateau's endorheic basin exhibited lake shrinkage before the mid‐1990s, but widespread and rapid lake expansions ever since. However, the quantitative contribution of glacier meltwater to lake changes, and the exact mechanisms behind its dominant drivers remain elusive. Here, a comprehensive examination of glacier mass balance since ∼1975 reveals that excess glacier meltwater compensated for net lake volume loss by 21% ± 5% during its contraction period 1975–1995, whereas promoted net volume gain by 9% ± 1% during expansion period 1995–2020 and by 17% ± 2% over the entire period 1975–2020. Further analyses reveal that the interdecadal variations of sea surface temperatures in the Atlantic, Pacific, and Indian Oceans favor a net moisture inflow to the Tibetan Plateau, leading to increased precipitation since 1995 relative to 1970s–1995, which effectively elucidates the climatic process causing rapid lake volume expansion in the endorheic basin. Plain Language Summary: Most of the lakes over the Tibetan Plateau are located in its endorheic basin in the Inner Plateau, forming a 700,000 km2 landlocked drainage area with an average elevation of over 4,000 m above sea level. An updated survey using comprehensive historic satellite images reveals a change in the trends of the number of lakes formed, their area, lake level, and volume over the past half a century, 1975–2020. The number and area of the lakes shrunk in 1975–1995, followed by an expansion in 1995–2020. Here, we elucidate the origin of this climatic change and conclude that excess glacier meltwater contributed to lake water balance by 21% during the lake contraction period 1975–1995. During the lake rapid expansion period of 1995–2020, mountain glaciers wasted at twice the rate during the earlier period; however, the contribution fraction remains smaller at 9%. The pattern of precipitation was the dominant driver of this multidecadal trajectory in lake change trends. The increases in precipitation since 1995 relative to 1970s−1995 was mainly induced by increased net moisture, which was attributable to interdecadal variations of sea surface temperature in the Atlantic, Pacific, and Indian Oceans. Key Points: Glacier melt compensated for net lake volume loss by 21% in 1975–1995 and promoted net lake volume gain by 9% in 1995–2020Glacier meltwater contributing to lake water gain mainly occurred in the southern Inner Tibetan PlateauTeleconnection of interdecadal sea surface temperature changes in three oceans was associated with increased precipitation and lake expansion [ABSTRACT FROM AUTHOR]