Harnessing the carbon-capturing potential of forests is a key component of plans to mitigate global climate change. Planting new forests is a common strategy, but this approach can have negative social and ecological impacts and substantial costs. Roebroek et al. instead investigated how ceasing management (e.g., wood harvesting or fire suppression) of forests would change their global carbon sequestration capacity. The authors assessed the differences between the biomass of similar forests with and without human activities and used machine learning to predict the additional biomass gain from removing human activities from global forests. Even if all management ceased (an extremely unlikely scenario), global forest carbon would only increase by about 15%. This work provides further evidence that changing forest management is not an alternative to cutting carbon emissions.