Widespread underestimation of rain-induced soil carbon emissions from global drylands

Journal Article · Sun Aug 31 20:00:00 EDT 2025 · Nature Geoscience

DOI:https://doi.org/10.1038/s41561-025-01754-9· OSTI ID:2587933

Nguyen, Ngoc B; Migliavacca, Mirco; Bassiouni, Maoya; Baldocchi, Dennis D; Gherardi, Laureano A; Green, Julia K; Papale, Dario; Reichstein, Markus; Cohrs, Kai-Hendrik; Cescatti, Alessandro; Nguyen, Tuan Dung; Nguyen, Hoang H; Nguyen, Quang Minh; Keenan, Trevor F

Dryland carbon fluxes, particularly those driven by ecosystem respiration, are highly sensitive to water availability and rain pulses. However, the magnitude of rain-induced carbon emissions remains unclear globally. Here we quantify the impact of rain-pulse events on the carbon balance of global drylands and characterize their spatiotemporal controls. Using eddy-covariance observations of carbon, water and energy fluxes from 34 dryland sites worldwide, we produce an inventory of over 1,800 manually identified rain-induced CO2 pulse events. Based on this inventory, a machine learning algorithm is developed to automatically detect rain-induced CO2 pulse events. Our findings show that existing partitioning methods underestimate ecosystem respiration and photosynthesis by up to 30% during rain-pulse events, which annually contribute 16.9 ± 2.8% of ecosystem respiration and 9.6 ± 2.2% of net ecosystem productivity. We show that the carbon loss intensity correlates most strongly with annual productivity, aridity and soil pH. Finally, we identify a universal decay rate of rain-induced CO2 pulses and use it to bias-correct respiration estimates. Our research highlights the importance of rain-induced carbon emissions for the carbon balance of global drylands and suggests that ecosystem models may largely underrepresent the influence of rain pulses on the carbon cycle of drylands.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Department of Energy; USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23), Climate and Environmental Sciences Division (SC-23.1 )
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2587933
• Journal Information: Nature Geoscience, Journal Name: Nature Geoscience Journal Issue: 9 Vol. 18
• Country of Publication: United States
• Language: English