A striking climate warming over the Tibetan Plateau during the last decades has been revealed by many studies, but evidence linking it to human activity is insufficient. By using historical observations, here we show that the in situ climate warming is accompanied by a distinct decreasing trend of the diurnal range of surface air temperature. The ERA40 reanalysis further indicates that there seems to be a coherent warming trend near the tropopause but a cooling trend in the lower stratosphere. Moreover, all these features can be reproduced in two coupled climate models forced by observed CO2 concentration of the 20th century but cannot be produced by the fixed external conditions before the industrial revolution. These suggest that the recent climate warming over the Tibetan Plateau primarily results from the increasing anthropogenic greenhouse gases emissions, and impacts of the increased greenhouse gases emissions upon the climate change in the plateau are probably more serious than the rest of the world.