At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.