Global wood demand is projected to rise but supply capacity is questioned due to limited global forest resources. Furthermore, the lifecycle global warming potential (GWP) impact of additional wood supply and use is poorly understood. For the case of a temperate country, combining forest carbon modelling and life-cycle assessment we show that sustained afforestation to double forest area alongside enhanced productivity can meet lower-bound wood demand projections from 2058. Thus, temperate forestry value-chains can achieve a cumulative GWP benefit of up to 265 Tg CO2-equivalent (CO2e) by 2100 for each 100,000 ha (expanding to 200,000 ha through afforestation) of forest. Net GWP balance depends on which overseas forests supply domestic shortfalls, how wood is used, and rate of industrial decarbonisation. There is considerable but constrained potential for increased wood-use to deliver future climate-change mitigation, providing it is connected with a long-term planting strategy, enhanced tree productivity and efficient wood use.