It is agreed that making Porland cement releases CO2, for heating but also due to the chemical reaction. Now I am informed that the concrete in my building is being damaged due to a slow but steady attack by CO2. So will the concrete ruins of our time be a CO2 absorber for the next generation?

For example, oak trees planted at a wide spacing tend to grow broad and massive, whereas if closely spaced they are more spindly, but there are far more of them per hectare.