More Wet Get Wetter
The 2006 paper by Held and Soden, Robust Responses of the Hydrological Cycle to Global Warming, is reassessed by the 2016 paper by Byrne and O’Gorman(2016) entitled The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land.
Figure 8.5 of the IPCC AR6 WGI compares the precipitation minus evaporation results of these two papers with those of CMIP6 simulations (solid blue line). Over this I have plotted the ERA5 P-E for the oceans (solid green line) and land (solid tan line). This comparison comes with the usual caveat that ERA5 is a reanalysis which is not constrained by actual observations of precipitation nor of evaporation and that these values, while physically consistent with analyzed inputs, may not represent actual P-E.
Over the oceans, there is an increase of P-E corresponding to the Inter-Tropical Convergence Zone. Over the sub-tropics, there is a decrease of P-E and over the high latitudes, there are some areas of increased P-E. The ERA5 reanalysis tends to support the “Wet get wetter, dry get drier”, over the oceans. The century trends over the oceans are closer to zero than are the trend from the simulation/scalings.
Over land, the simulations, scaling estimates, and reanalysis all diverge from one another for significant areas. The extrapolated century trend from reanalysis tends to be close to zero for most areas, which appears to support the Byrne and O’Gorman idea that the “wet get wetter, dry get drier” does not hold over land.
Also of note, the ERA5 reanlysis does not indicate much change of P-E over high northerly latitude land in contrast with the simulations and scaling estimates above.
Byrne, M. P., & O’Gorman, P. A. (2015). The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land, Journal of Climate, 28(20), 8078-8092. Retrieved May 20, 2022, from https://journals.ametsoc.org/view/journals/clim/28/20/jcli-d-15-0369.1.xml
Copernicus Climate Change Service (C3S) (2017): ERA5: Fifth generation of ECMWF atmospheric reanalyses of the global climate, Copernicus Climate Change Service Climate Data Store (CDS), accessed May 6, 2020, https://cds.climate.copernicus.eu/cdsapp#!/home.
Held, I. M., & Soden, B. J. (2006). Robust Responses of the Hydrological Cycle to Global Warming, Journal of Climate, 19(21), 5686-5699. Retrieved May 20, 2022, from https://journals.ametsoc.org/view/journals/clim/19/21/jcli3990.1.xml