Atmospheric water vapor (TPW) and climate change
6 hours ago Andy May 15 Comments
By Andy May
In the latest IPCC major report, AR6, they report: “a best estimate of equilibrium climate sensitivity of 3°C, with a very likely range of 2°C to 5°C”.[1] They also report that CO2 concentration might control climate change.[2] This estimate includes the laboratory estimate that CO2 alone, if doubled in the atmosphere, would increase the average global surface temperature about 1.2°C.[3] The remaining 1.8°C (60%) is supposedly achieved through feedbacks to the initial CO2-caused warming. The main proposed feedback mechanism is an increase in atmospheric water vapor caused by the CO2 warmed air.[4] Water vapor is a more powerful greenhouse gas than CO2, due to its greater abundance, and can cause more warming.[5]
The IPCC estimates the water vapor feedback using the Clausius-Clapeyron relation. The relation states that as temperature increases, more evaporation occurs and atmospheric water vapor increases, especially in the upper atmosphere.[6] Models suggest that relative humidity should remain “roughly constant,” as climate changes.[7] According to AR5 and AR6:
“… total column water vapour (TCWV) very likely increased since the 1970s, at a rate that was overall consistent with the Clausius-Clapeyron relationship (about 7% per °C) given the observed increase in atmospheric temperature.”
(IPCC 2021, p 330).
Later in the report they write this:
https://wattsupwiththat.com/2023/03/21/atmospheric-water-vapor-tpw-and-climate-change/
