An investigation of the global uptake of CO2 by lime from 1963 to 2020

Abstract. Lime is responsible for the continuous and stable absorption of CO2 from the atmosphere during its cycle via the carbonation reaction. However, the magnitude of the global uptake of CO2 by lime under natural conditions remains unclear. Here, existing data on materials associated with the production, utilisation, and disposal stages of lime-containing materials were analysed using a comprehensive model to obtain regional and global estimates for the sequestration of carbon from 1963 to 2020. The CO2 emissions linked to the production of lime during the investigated period were also estimated. The results reveal that the global uptake of CO2 by lime increased from 38.25 Mt (95 % confidence interval, CI:27.85-51.38 Mt) in 1963 to 134.33 Mt (95 % CI:90.37-139.29 Mt) in 2020. Cumulatively, approximately 4.05 Gt of CO2 (95 % CI:3.02-5.25 Gt CO2) were sequestered by lime produced between 1963 and 2020, and this amount corresponds to 38.79 % of CO2 emissions from the associated process during the period. Lime-containing materials in China accounted for 63.12 % of the total uptake, and among the three stages of the lime cycle, the utilisation stage accounted for the highest CO2 sequestration (~74.05 %). The results also demonstrate that lime, which is usually omitted from emission inventories as a carbon sink, is very important to the carbon cycle. The present study indicates that the CO2 uptake by lime can reduce the carbon footprint of lime production process and provide scientific proof for further research of the potential of lime-containing materials in carbon capture and storage. The ** data utilised in the present study can be accessed at https://doi.org/10.5281/zenodo.7112485 (Ma, 2022)