Tropical deforestation has increasingly become a global concern, exerting profound impacts on regional and global climates through processes such as water and heat exchange. Conventional research suggests that tropical deforestation should lead to a significant reduction in local and regional precipitation due to decreased evapotranspiration (ET), which in turn reduces atmospheric moisture. However, numerous studies have revealed that the effects of deforestation on precipitation are complex.

Observations at small spatial scales often show increased precipitation, while significant negative effects on precipitation are only detectable at larger spatial scales. This indicates a clear scale-dependent relationship between deforestation and precipitation. Despite decades of research by scientists worldwide, the mechanisms driving this scale-dependent effect remain poorly understood.

Professor Zhenzhong Zeng’s research group from the School of Environmental Science and Engineering at the Southern University of Science and Technology (SUSTech) has made significant progress in understanding how Amazon deforestation affects precipitation. Utilizing a newly improved regional climate model (Qin et al., GRL, 2023) combined with high-resolution remote sensing data on forest cover, the group has, for the first time, uncovered a novel mechanism where the impact of Amazon deforestation on precipitation reverses between seasons (Figure 1).

Their findings, titled “Impact of Amazonian deforestation on precipitation reverses between seasons”, have been published in the prestigious academic journal Nature.

Figure 1. Simulated contrasting precipitation responses to deforestation at different scales over the Amazon region

By refining the regional climate model and integrating an advanced moisture-tracking module, the researchers have, for the first time, explained the driving mechanisms behind the scale-dependent effects of Amazon deforestation on precipitation and their seasonal variations (Figure 2). This discovery systematically elucidates the critical roles of both local and non-local moisture sources in regulating the deforestation-precipitation relationship. The interaction between these factors also creates distinct differences between dry and wet seasons, reshaping our understanding of deforestation-precipitation dynamics and having far-reaching implications for forest conservation and climate science in tropical regions.

Figure 2. Mechanisms of deforestation-precipitation feedback in the Amazon during the wet and dry seasons

Furthermore, the study’s methodology provides an innovative perspective for investigating land-based precipitation effects. The incorporation of moisture and scale perspectives enhances the understanding of precipitation dynamics, while the model improvements significantly boost the performance of regional climate models in capturing deforestation-related climate feedback. This approach has great potential for application in other global hotspots.

Ph.D. student Yingzuo Qin from the School of Environmental Science and Engineering at SUSTech is the first author of the paper. Professor Zhenzhong Zeng is the corresponding author. Other collaborators of this study include Research Assistant Professor Dashan Wang from SUSTech, Professor Alan D. Ziegler from Chiang Mai University, Thailand, and Researcher Bojie Fu from the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. SUSTech is the first affiliated institution for this work.

Paper link: https://www.nature.com/articles/s41586-024-08570-y

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