Global carbon uptake by cement carbonation

Calcination of carbonate rocks during the manufacture of cement produced emissions equivalent to 5% of global fossil CO2 emissions in 2013. Considerable attention has been paid to quantifying these industrial process emissions from cement production, but the natural reversal of the process—carbonation, has received almost no attention in carbon cycle studies. Here, we show carbonation of cement materials over their life cycle represents a large and growing net sink of CO2 (0.10 GtC y-1 in 1998 to 0.25 GtC y-1 in 2013). In total, we estimate that a cumulative amount of 4.5 GtC (2.8-7.5, p= 0.05) has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the process CO2 emissions from production of cement (excluding those from related fossil energy inputs) over the same period. The emissions inventories prepared using IPCC guidelines and used by recent carbon cycle …