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Warming Reduces Relative Humidity Through Soil Moisture 


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Revisions’ Spotlights are overviews of recent articles by the journal editors at AGU.

Source: Geophysical Research Letters

As the concentration of greenhouse gases continues to rise, the Earth’s temperature is expected to increase, leading to a decline in relative humidity (RH) over land. In the past, it was believed that this decrease in RH was primarily caused by the ocean’s impact on changes in land surface energy and moisture. However, according to Zhou et al. [2023], land RH can decrease independently from ocean influence.

This research utilized CMIP6 models and conducted experiments with a coupled land-atmosphere model, comparing interactive soil moisture to prescribed soil moisture. The results demonstrate that interactive soil moisture is both necessary and effective in reducing land relative humidity (RH). When soil moisture is prescribed and not allowed to respond to climate change, climate models do not show a decrease in land RH. However, in the idealized radiative-convective equilibrium mode without an ocean, warming leads to a decrease in soil moisture and subsequently a decrease in land RH.

This research highlights the significance of land surface activities in regulating the response of relative humidity to warming. It emphasizes the importance of further investigation in comprehending the underlying mechanisms for how soil moisture adapts to variations in surface fluxes and ultimately reaches a drier equilibrium.

Citation: Zhou, W., Leung, L. R., & Lu, J. (2023). The role of interactive soil moisture in land drying under anthropogenic warming. Geophysical Research Letters, 50, e2023GL105308. https://doi.org/10.1029/2023GL105308

“The editor of Geophysical Research Letters is Guiling Wang.”

Text © 2023. The authors. CC BY-NC-ND 3.0

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