J. Clim. https://doi.org/10.1175/JCLI-D-19-0145.1 (2019).

Land precipitation is vital to populations and ecosystems worldwide. Globally, terrestrial precipitation has two main sources: evaporation off the ocean surface or via ‘recycled’ moisture from evaporation (and transpiration) over land.

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Kirsten Findell, from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, and colleagues in the US and the Netherlands use climate models, reanalysis datasets and a moisture tracking algorithm to estimate historical patterns and future changes to moisture recycling. Historically, they find that around 55% of terrestrial evaporation is recycled and precipitates back on land, while about 40% of land precipitation originates as land evaporation.

The researchers estimate that moisture recycling will decrease 2–3% per °C increase, despite expected global increases in precipitation and evaporation. These results, coupled with inherent moisture limitations of the land surface, imply that the importance of the ocean as a moisture source to land will increase with warming. This is consequential for rain-fed agricultural regions, where crops that rely on recycled precipitation will become increasingly soil-moisture limited.