A doubled increasing trend of evapotranspiration on the Tibetan Plateau

Estimation of evapotranspiration (ET_a) change on the Tibetan Plateau (TP) is essential to address the water requirement of billions of people surrounding the TP. Existing studies have shown that ET_a estimations on the TP have a very large uncertainty. In this article, we discuss how to more accurately quantify ET_a amount and explain its change on the TP. ET_a change on the TP can be quantified and explained based on an ensemble mean product from climate model simulations, reanalysis, as well as ground-based and satellite observations. ET_a on the TP experienced a significant increasing trend of around 8.4 ± 2.2 mm (10 a)^-1 (mean ± one standard deviation) during 1982-2018, approximately twice the rate of the global land ET_a (4.3 ± 2.1 mm (10 a)^-1). Numerical attribution analysis revealed that a 53.8% TP area with the increased ET_a was caused by increased temperature and 23.1% part was due to soil moisture rising, because of the warming, melting cryosphere, and increased precipitation. The projected future increase in ET_a is expected to cause a continued acceleration of the water cycle until 2100.