Some people like to refer to concrete as cement. But that is technically incorrect. Cement is just one of the main ingredients in concrete, along with water and aggregates. So it's a bit like referring to a beer as a bottle of yeast.

That said, cement is pretty integral to concrete and it's largely the reason why the embodied carbon is so high in this widely-used building material. According to Brian Potter, cement production is responsible for somewhere between 5-10% of global CO2 emissions.

This is coming from the roughly 4.25 billion metric tons of cement that is produced annually and the 30 billion tons of concrete that it ends up in. The world likes concrete. And in particular, China likes concrete.

China alone is now producing about half of the world's cement. And since consumption generally tracks production, and the consumption of cement generally translates into concrete, China is using, by far, the most concrete.

I don't know what the right answer is to this particular carbon problem, but Brian Potter's latest construction physics post is perhaps a good place to start thinking about it. In it, he covers who is producing it, where it is being used, and how we might get to a world with less concrete.