evidence: Land degradation is a driver of climate change through emission of greenhouse gases (GHGs) and reduced rates of carbon uptake (very high confidence). Since 1990, globally the forest area has decreased by 3% (low confidence) with net decreases in the tropics and net increases outside the tropics (high confidence). Lower carbon density in re-growing forests, compared to carbon stocks before deforestation, results in net emissions from land-use change (very high confidence). Forest management that reduces carbon stocks of forest land also leads to emissions, but global estimates of these emissions are uncertain. Cropland soils have lost 20–60% of their organic carbon content prior to cultivation, and soils under conventional agriculture continue to be a source of GHGs (medium confidence). Of the land degradation processes, deforestation, increasing wildfires, degradation of peat soils, and permafrost thawing contribute most to climate change through the release of GHGs and the reduction in land carbon sinks following deforestation (high confidence). Agricultural practices also emit non-CO2 GHGs from soils and these emissions are exacerbated by climate change (medium confidence). Conversion of primary to managed forests, illegal logging and unsustainable forest management result in GHG emissions (very high confidence) and can have additional physical effects on the regional climate including those arising from albedo shifts (medium confidence). These interactions call for more integrative climate impact assessments. {4.2.2, 4.3, 4.5.4, 4.6}