Meta-analysis shows the impacts of ecological restoration on greenhouse gas emissions.

International initiatives set ambitious targets for ecological restoration, which is considered a promising greenhouse gas mitigation strategy. Here, we conduct a meta-analysis to quantify the impacts of ecological restoration on greenhouse gas emissions using a dataset compiled from 253 articles. Our findings reveal that forest and grassland restoration increase CH uptake by 90.0% and 30.8%, respectively, mainly due to changes in soil properties. Conversely, wetland restoration increases CH emissions by 544.4%, primarily attributable to elevated water table depth. Forest and grassland restoration have no significant effect on NO emissions, while wetland restoration reduces NO emissions by 68.6%. Wetland restoration enhances net CO uptake, and the transition from net CO sources to net sinks takes approximately 4 years following restoration. The net ecosystem CO exchange of the restored forests decreases with restoration age, and the transition from net CO sources to net sinks takes about 3-5 years for afforestation and reforestation sites, and 6-13 years for clear-cutting and post-fire sites. Overall, forest, grassland and wetland restoration decrease the global warming potentials by 327.7%, 157.7% and 62.0% compared with their paired control ecosystems, respectively. Our findings suggest that afforestation, reforestation, rewetting drained wetlands, and restoring degraded grasslands through grazing exclusion, reducing grazing intensity, or converting croplands to grasslands can effectively mitigate greenhouse gas emissions.