Atmospheric Circulation Adjustments and Precipitation Redistribution Driven by Global Deforestation: Insights from CMIP6 Models
Year: 2026
Type: article
Abstract: Large-scale deforestation can profoundly affect the global energy balance, the hydrological cycle, and large-scale atmospheric circulation through modifications of biogeophysical processes such as surface albedo, evapotranspiration, and aerodynamic roughness. Previous studies have primarily focused on the local-scale impacts of deforestation on temperature and the water cycle, yet how deforestation reshapes precipitation patterns in regions remote from the deforested areas through atmospheric circulation adjustments–particularly how mid-to-high-latitude circulation changes propagate to the tropics via meridional and zonal atmospheric teleconnection processes–remains insufficiently understood. Using idealized global deforestation experiments from 11 CMIP6-LUMIP Earth system models, this study systematically investigates the cross-scale climate effects of global deforestation from the mid-to-high latitudes to the tropics, along with the underlying physical mechanisms. Multi-model ensemble results consistently show that deforestation induces significant cooling over the Northern Hemisphere mid-to-high latitudes. This cooling is primarily driven by the snow–albedo masking effect and its associated positive feedback mechanism: deforestation exposes high-albedo snow-covered surfaces that were previously masked by forest canopies. Multi-model stratified analyses reveal that when the deforested fraction exceeds 30%, the surface albedo increase caused by snow exposure is approximately four times that of equivalent deforestation in snow-free regions. The resultant cooling, in turn, tends to promote snow-cover expansion, forming a positive feedback that further amplifies the cooling magnitude. The mid-to-high-latitude cooling strengthens the meridional temperature gradient; multi-model diagnostics indicate a tendency for the polar vortex to deepen and contract, accompanied by an overall intensification of the mid-latitude westerlies. Diagnostics of the divergent wind and velocity potential fields further reveal that the enhanced westerlies tend to generate low-level convergence along the western margins of continents–favoring increased precipitation–and divergence along the eastern margins–suppressing precipitation. This dynamical process may constitute an important mechanism underlying the east–west asymmetric redistribution of precipitation at mid-to-high latitudes. In the tropics, the interhemispheric thermal asymmetry induced by deforestation drives an asymmetric response of the Hadley circulation. In most models, the Intertropical Convergence Zone (ITCZ) exhibits weakened intensity and increased width, accompanied by reduced precipitation in the deep tropics and enhanced precipitation on its flanks. Concurrently, the cold signal originating from the Northern Hemisphere mid-to-high latitudes is transmitted to the western Pacific warm pool region primarily through atmospheric circulation adjustments, supplemented by oceanic heat transport. During the simulated quasi-equilibrium period (years 50–79), this process weakens the zonal sea surface temperature gradient across the Pacific, driving an "El Niño–like" weakening of the Walker circulation, manifested as decreased precipitation over the northwestern Pacific and increased precipitation over the central-to-eastern Pacific. However, preliminary analyses based on extended-duration simulations from individual models suggest that, on longer timescales, the intensification of equatorial upwelling in the eastern Pacific may bring subsurface cold water to the surface, gradually restoring the zonal sea surface temperature gradient and attenuating–or even reversing–the weakening trend of the Walker circulation. This long-term evolutionary feature, however, requires further verification across a broader range of models. These findings elucidate several key processes through which the climate effects of deforestation propagate from the mid-to-high latitudes to the tropics, and highlight that oceanic dynamical feedbacks may play a non-negligible regulatory role in the remote climate effects of land surface forcing.
Source: Työväentutkimus Vuosikirja
Author: Peng, Ke
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: green
OpenAlex ID: W7198485941