While strolling down a sidewalk, you probably don’t consider how the cement beneath your feet affects the climate. But cement production causes about five percent of global carbon dioxide emissions.

Those emissions come from the process of converting limestone to lime, the key ingredient in cement, and from the fossil fuels that factories burn during the production process.

But a recent study shows that the net impact of cement might not be quite as bad as previously thought. That’s because, in a process called carbonation, cement reabsorbs some carbon dioxide from the atmosphere.

Liu: “So even though the process goes very slowly, these materials do have a very significant amount of carbon uptake.”

That’s researcher Zhu Liu, who is now at the California Institute of Technology in Pasadena. He and a team of scientists found that between the years 1930 and 2013, cement reabsorbed almost half of the emissions that were created during the limestone conversion process.

This does not mean that making new cement is good for the climate. But it does mean finding ways to reuse or recycle existing cement materials – like that sidewalk under your feet – can help reduce global warming.

Reporting credit: ChavoBart Digital Media.

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