The climate benefits of cement carbonation are being overestimated due to the slow rate of carbonation and the timing of emissions and uptake. This study shows that global cement carbonation re-absorbs about 13.8 Gt of CO₂ from 1930–2015, but the actual climate benefit is about 60% smaller. Demolition emissions from crushing concrete can offset carbon uptake during demolition. The study highlights the importance of considering the timing of emissions and uptake when assessing the climate benefits of carbonation. It also shows that the use of supplementary cementitious materials (SCMs) can increase carbonation rates and reduce production emissions. The study uses time-adjusted warming potential (TAWP) to account for the timing of emissions and uptake, which provides a more accurate assessment of the climate benefits of carbonation. The study finds that the climate benefits of carbonation are significantly smaller than previously estimated, and that the use of SCMs can provide greater benefits. The study also shows that the carbonation of concrete can be influenced by factors such as the type of SCM used, the particle size of the concrete, and the environmental conditions. The study concludes that the climate benefits of cement carbonation are being overestimated and that more accurate assessments are needed to determine the true potential of carbonation in reducing emissions.The climate benefits of cement carbonation are being overestimated due to the slow rate of carbonation and the timing of emissions and uptake. This study shows that global cement carbonation re-absorbs about 13.8 Gt of CO₂ from 1930–2015, but the actual climate benefit is about 60% smaller. Demolition emissions from crushing concrete can offset carbon uptake during demolition. The study highlights the importance of considering the timing of emissions and uptake when assessing the climate benefits of carbonation. It also shows that the use of supplementary cementitious materials (SCMs) can increase carbonation rates and reduce production emissions. The study uses time-adjusted warming potential (TAWP) to account for the timing of emissions and uptake, which provides a more accurate assessment of the climate benefits of carbonation. The study finds that the climate benefits of carbonation are significantly smaller than previously estimated, and that the use of SCMs can provide greater benefits. The study also shows that the carbonation of concrete can be influenced by factors such as the type of SCM used, the particle size of the concrete, and the environmental conditions. The study concludes that the climate benefits of cement carbonation are being overestimated and that more accurate assessments are needed to determine the true potential of carbonation in reducing emissions.