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This study comprehensively analyzed long-term (1960–2014) variations of potential and actual evapotranspiration (ET) and quantified their inter-annual and seasonal sensitivity and attribution to climate and vegetation growth changes in the upper reaches of the Yellow River Basin (UYRB). Satellite-derived vegetation greenness and in situ measured hydrometeorological datasets were used. Average annual reference evapotranspiration (ET₀) showed significant decreasing trend (p < 0.05) by 0.32 mm year⁻¹ over the past 55 years. Results obtained from recovered stationary series and sensitivity analyses showed that reduction of wind speed was the major driving force for decreasing trends in annual and seasonal ET₀. Water budget-derived actual evapotranspiration (ET_a) increased dramatically during the study period, whereas potential evapotranspiration (ET_p) calculated from Penman equation and pan …