2025-02-26 マックス・プランク研究所
＜関連情報＞
- https://www.mpg.de/24234854/amazon-rainforest-tipping-point-precepitation
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL110503
森林伐採に伴うアマゾンの降雨の減衰が、全球の暴風雨解像モデルで再現される Muted Amazon Rainfall Response to Deforestation in a Global Storm-Resolving Model
Arim Yoon, Cathy Hohenegger
Geophysical Research Letters Published: 19 February 2025
DOI:https://doi.org/10.1029/2024GL110503
Abstract
Ongoing Amazon deforestation has raised concerns about forest dieback via induced precipitation changes. Previous studies have found that complete deforestation reduces evapotranspiration, contributing to low precipitation rates that would limit the regrowth of the forest, but such studies have used climate models with convective parameterization and/or fixed large-scale circulation. For the first time, we simulate a complete Amazon deforestation scenario without convective parameterization, allowing full interaction between convection and large-scale circulation, for 3 years. Our results show no significant reduction in annual mean precipitation. Changes in the 700 hPa circulation and associated moisture convergence compensate for the reduction in evapotranspiration. These changes also lead to a north-south dipole pattern in the precipitation response during the dry and wet seasons. The uncovered dynamics suggest that Amazon mean precipitation may be more resilient to land surface perturbations than previously thought.
Key Points
- This study is the first to explore the response of Amazon precipitation to complete deforestation using a global storm-resolving model
- Despite a strong decrease in evapotranspiration, mean Amazon precipitation shows no significant change
- The muted precipitation response is explained by enhanced moisture convergence at 700 hPa following large-scale circulation changes
Plain Language Summary
Previous studies have widely reported that, past a critical threshold, deforestation of the Amazon forest would result in the loss of so much rainfall that the rainforest could no longer sustain itself. However, these results are questionable because previous studies have had to either parameterize convective processes or use prescribed large-scale circulation, even though precipitation in the Amazon forest results from convective processes, with moisture supplied by evapotranspiration and large-scale circulation. Here, we bypass these two limitations. We simulate, for the first time, a complete Amazon deforestation scenario without using a convective parameterization and allow for full interactions between explicitly resolved convective storms and the large-scale circulation. Contrary to previous studies, we find no significant reduction in Amazon mean precipitation following deforestation. This results from changes in the large-scale circulation that compensate for the reduction in evapotranspiration. Our study suggests that changes in mean precipitation following deforestation will not cause a tipping point and the forest could recover.
