We take it for granted, but concrete is the foundation (no pun intended) of countless buildings, homes, bridges, skyscrapers, millions of miles of highways, and some of the most impressive feats of civil engineering the world has ever known. It’s the most widely-used human-made substance on the planet.
It also happens to be incredibly bad for the climate. Portland cement, the most commonly used base (the goop that gets mixed with sand and gravel, or aggregate, to form concrete), is made with limestone that is quarried and then heated to staggeringly high temperatures — releasing huge amounts of carbon dioxide in the process. Add to that all the fuel burned to mine and crush the aggregate, and you’ve got a climate disaster.