The majority of the carbon footprint of the cement industry originates from the decomposition of alkaline carbonates during clinker production. Recent studies have demonstrated that calcium oxides and other alkaline oxides in cement materials can sequester CO₂ through the carbonation process and partially offset the carbon emissions generated during cement production. This study employs a comprehensive analytical model to estimate the CO₂ uptake via hydrated cement carbonation, including concrete, mortar, construction waste, and cement kiln dust (CKD), covering major cement production and consumption regions worldwide from 1930 to 2023. In 2023, the global annual cement CO₂ uptake reached 0.93 Gt/yr (95% CI: 0.80–1.13Gt/yr). From 1930 to 2023, the global cumulative cement CO₂ absorption reached 23.89 Gt (95% CI: 20.47–28.74 Gt), equivalent to 52.32% of the CO₂ process emissions from cement production during the same period. Our system for estimating cement emissions and uptake is updated annually, providing consistent and accurate data for the cement industry and carbon cycle studies. This data supports improved adaptation to future challenges.

The hydration products of cement materials can absorb atmospheric CO₂, and this carbonation process provides an important decarbonization pathway for the cement industry. Global carbon sequestration by cement materials has been reported, but carbon uptake in different countries remains unquantified. Here, we quantify the national cement carbon uptake from 1928 to 2023 based on 58 517 activity data from 163 cement-producing countries and regions worldwide and 6186 carbonation parameters from detailed data records of 42 countries, and we project the trend in carbon uptake by countries in 2024. The global CO₂ uptake by cement materials has increased from 7.74 Mt yr⁻¹ (95 % confidence interval, CI: 5.84–9.85 Mt CO₂ yr⁻¹) in 1928 to 0.84 Gt yr⁻¹ (95 % CI: 0.71–1.00 Gt yr⁻¹) in 2023, and it was projected to rise to 0.86 Gt yr⁻¹ (95 % CI: 0.73–1.02 CO₂ yr⁻¹) in 2024. The accumulated CO₂ uptake from 1928 to 2023 is 21.26 Gt CO₂ (95 % CI: 17.93–25.17 Gt CO₂), which offsets about 46 % of the cement process emissions (46.06 Gt CO₂) in the past 96 years. Simultaneously, the dominance in cement carbon uptake has shifted from the USA, Japan, and some European countries to emerging economies such as China and India, which account for 38.0 % and 9.1 % of total CO₂ uptake, respectively, in the last decade (2014–2023). By analysing the long time series of carbon emissions and uptake of the 42 countries with detailed data, we find that they contributed 82.1 % of global cement CO₂ uptake from 1928 to 2023, including 21 countries for which cement emissions have peaked and 21 countries for which they have not yet peaked. The annual carbon offset level (the ratio of uptake to process emissions in a given year) shows a remarkable decrease due to the temporal lag in cement carbon uptake. This is significant for countries with higher cement imports; for example, the cement industries in Australia and Japan have achieved net-zero emissions when considering the cement carbonation sink. This study provides an accurate bottom-up quantification of cement carbonation sinks at national and global levels. All of the data described in this study are accessible at https://doi.org/10.5281/zenodo.14583866 (Wu et al., 2024).

Amid increasing pressure to reduce carbon emissions and address the energy crisis, solar power has emerged as a key alternative to fossil fuels. China possesses extensive abandoned open-pit mines suitable for photovoltaic (PV) power development; however, their carbon mitigation and energy conservation potential remains largely underutilized. In this study, we develop an integrated model to quantify the life-cycle carbon mitigation potential of PV systems on these mines, combining PV power generation with ecological restoration of mine sites. The results indicate that developing PV systems on abandoned open-pit mines in China could generate 1.34-2.93 EJ yr-1 of renewable energy and reduce CO2 emissions by 278.85-613.79 Mt yr-1, accounting for 5.9%-12.8% of China’s coal-fired power generation and 2.8%-6.2% of its carbon emissions in 2020. Replacing conventional electricity with PV power yields greater carbon mitigation (611.63 t CO2 ha-1) than bioenergy alternatives, including biopower (102.96 t CO2 ha-1), ethanol (61.99 t CO2 ha-1), and biodiesel (17.13 t CO2 ha-1). Inner Mongolia, Xinjiang, Shandong, Hebei, Guangxi, and Yunnan were identified as key provinces with high renewable energy production and corresponding CO2 mitigation potential, collectively contributing 44%-45% of the total mitigation potential. Overall, an energy-oriented ecological restoration model, such as the “PV+” scenarios for abandoned open-pit mines, is economically feasible. This study provides geographically tailored information to help decision-makers optimize the use of multifunctional land resources, supporting the green transformation of the mining industry and advancing China’s dual carbon targets.