To determine forest carbon emissions by tracking the life cycle of harvested wood, it is essential to quantify the carbon stocks in forest ecosystems and to understand how they change with harvests. Converting mature forests to young forests results in a considerable loss of carbon stocks through harvesting, even when carbon storage in wood products is included, as the authors make clear, and future carbon stocks will always be less than those retained if no harvest occurs. Modelling has shown previously that the density of carbon expected to be stored in a mature unharvested forest is much higher than that in a mature harvested forest 120 years after harvest - even when the carbon in wood products is combined with the carbon storage after harvest8.