Global total precipitable water variations and trends over the period 1958-2021

Global responses of the hydrological cycle to climate change have been widely studied, but uncertainties still remain regarding water vapor responses to lower-tropospheric temperature. Here, we investigate the trends in global total precipitable water (TPW) and surface temperature from 1958 to 2021 using ERA5 and JRA-55 reanalysis datasets. We further validate these trends using radiosonde from 1979 to 2019 and Atmospheric Infrared Sounder (AIRS) and Special Sensor Microwave Imager/Sounder (SSMIS) observations from 2003 to 2021. Our results indicate a global increase in total precipitable water (TPW) of ∼ 2 % per decade from 1993-2021. These variations in TPW reflect the interactions of global warming feedback mechanisms across different spatial scales. Our results also revealed a significant near-surface temperature (T_2m) warming trend of ∼ 0.15 Kdecade-1 over the period 1958-2021. The consistent warming at a rate of ∼ 0.21 Kdecade^-1 after 1993 corresponds to a strong water vapor response to temperature at a rate of 9.5 % K^-1 globally, with land areas warming approximately twice as fast as the oceans. The relationship between TPW and T_2m showed a variation of around 6 %K^-1-8 % K^-1 in the 15-55° N latitude band, aligning with theoretical estimates from the Clausius-Clapeyron equation.