Global urban reforestation can be an important natural climate solution

The climate mitigation potential of urban nature-based solutions (NBSs) is often perceived as insignificant and thus overlooked, as cities primarily pursue NBSs for local ecosystem services. Given the rising interest and capacities in cities for such projects, the potential of urban forests for climate mitigation needs to be better understood. We modelled the global potential and limits of urban reforestation worldwide, and find that 10.9 +/- 2.8 Mha of land (17.6% of all city areas) are suitable for reforestation, which would offset 82.4 +/- 25.7 MtCO(2)e yr(-1) of carbon emissions. Among the cities analysed, 1189 are potentially able to offset >25% of their city carbon emissions through reforestation. Urban natural climate solutions should find a place on global and local agendas.

Automated summary

This study found that approximately 17.6% of urban areas globally are suitable for reforestation, which could offset 82.4 +/- 25.7 million tons of carbon dioxide emissions. 1189 cities have the potential to offset more than 25% of their city carbon emissions through reforestation. Urban natural climate solutions should be prioritized on global and local agendas.