Reference evapotranspiration (ET₀) is a key component of the water cycle. In this study, a modified Penman–Monteith method incorporating the CO₂ effect on surface resistance was used to estimate past change in ET₀ in China for 1961–2019 and to project future changes for 2040–2099. A partial-differential equation was used to attribute the changes in ET₀. Results indicated the following. (1) A shift point in the annual ET₀ series occurred in 1993, in which annual ET₀ in China had been decreasing and then increased significantly by −18.93 and 11.19 mm·decade^-1 before and after 1993, respectively, with ET₀ having changed most drastically within the temperate continental climate zone. (2) Wind speed and solar radiation were the major dominant factors responsible for the change in ET₀ during 1961–1992, and their contribution rates were 48.30 and 38.92 %, respectively. During 1993–2019, increasing maximum air temperature was the dominant factor contributing to increasing ET₀, with a contribution rate of 81.71%, yet wind speed was the dominant factor affecting ET₀ changes at 45% of the stations in China. (3) In future projections, maximum air temperature is expected to be the dominant factor influencing the increase in ET₀, the values of which were projected at 1.49 and 16.05 mm·decade^-1 during 2040–2099 under RCP4.5 and 8.5 scenarios, respectively, with projections from five GCMs. The increasing surface resistance response to elevated CO₂ was found to be an important contributor to the decrease in ET₀. Particularly for the RCP8.5 scenario, the increase in surface resistance was found to lead to the decrease in ET₀ by −0.68 mm·year⁻¹ (-42.37%). This suggests that historical and future tendencies towards aridity in China may be considerably weaker and less extensive than previously assumed.