Roughly half of the world’s forest cover has been cleared for agriculture and most of the remainder is used by humans in one way or the other. Strong further changes are expected for the future, because reforestation, afforestation and forest management have been assigned prime roles in the effort to limit global warming to 2 degrees. Understanding and quantifying the effects of forests on local, regional and global climate in the past and in future scenarios is thus of high importance, yet accompanied by diverging, sometimes contradicting, results in the literature. The potential of reforestation and afforestation to take up and store CO2 may have been overestimated in some studies by neglecting socioeconomic constraints, but may still reach on the order of 2 PgC/year, making it one of the negative emission technologies with large potential. Global mitigation aspects, however, may be dwarfed by effects forest and forest management changes have on local climate via biogeophysical pathways, where temperatures may be altered by several degrees. This could turn reforestation, afforestation and forest management into important tools for adaptation to climate change. Studies disagree, however, which surface property is responsible for the local response. Earlier modeling studies suggested afforesting dark boreal forest may warm climate due to the albedo decrease, though more recent observation-based studies suggest that in fact effects from the higher roughness (i.e. more energy transfer away from the surface) may dominate, with a cooling. Here, I try to resolve some of the discrepancies and set the frame for discussing how to increase the contribution of forests and forest management to mitigating and to adapting to anthropogenic climate change.