This study examines the combined climate and carbon-cycle effects of large-scale deforestation using a three-dimensional coupled global carbon-cycle and climate model. Deforestation releases carbon dioxide (CO₂) into the atmosphere, contributing to global warming. However, biophysical effects such as changes in albedo, evapotranspiration, and cloud cover also influence climate. The study finds that global-scale deforestation has a net cooling effect because the warming from carbon-cycle effects is outweighed by cooling from biophysical effects like albedo and evapotranspiration changes. Latitude-specific experiments show that afforestation in the tropics would be beneficial for mitigating global warming, while afforestation in high latitudes would be counterproductive. Temperate regions offer only marginal benefits. The study highlights that while carbon-cycle effects are global, biophysical effects are more regional. The results suggest that afforestation in the tropics is more effective for climate mitigation than in temperate or high latitude regions. The study also notes that forests have significant environmental value beyond climate mitigation, including biodiversity conservation, water protection, and carbon sequestration. The results emphasize the need for comprehensive climate-carbon models to evaluate the full impact of deforestation and afforestation. The study warns against viewing deforestation as a climate mitigation strategy, as it can have negative ecological consequences. The findings suggest that large-scale afforestation in temperate regions may be ineffective for climate mitigation, and that the climate impact of deforestation depends on regional factors. The study concludes that preserving ecosystems is crucial for climate change mitigation, and that deforestation outside the tropics should not be considered a viable strategy for climate mitigation due to its ecological and environmental impacts.This study examines the combined climate and carbon-cycle effects of large-scale deforestation using a three-dimensional coupled global carbon-cycle and climate model. Deforestation releases carbon dioxide (CO₂) into the atmosphere, contributing to global warming. However, biophysical effects such as changes in albedo, evapotranspiration, and cloud cover also influence climate. The study finds that global-scale deforestation has a net cooling effect because the warming from carbon-cycle effects is outweighed by cooling from biophysical effects like albedo and evapotranspiration changes. Latitude-specific experiments show that afforestation in the tropics would be beneficial for mitigating global warming, while afforestation in high latitudes would be counterproductive. Temperate regions offer only marginal benefits. The study highlights that while carbon-cycle effects are global, biophysical effects are more regional. The results suggest that afforestation in the tropics is more effective for climate mitigation than in temperate or high latitude regions. The study also notes that forests have significant environmental value beyond climate mitigation, including biodiversity conservation, water protection, and carbon sequestration. The results emphasize the need for comprehensive climate-carbon models to evaluate the full impact of deforestation and afforestation. The study warns against viewing deforestation as a climate mitigation strategy, as it can have negative ecological consequences. The findings suggest that large-scale afforestation in temperate regions may be ineffective for climate mitigation, and that the climate impact of deforestation depends on regional factors. The study concludes that preserving ecosystems is crucial for climate change mitigation, and that deforestation outside the tropics should not be considered a viable strategy for climate mitigation due to its ecological and environmental impacts.