As cities around the world expand, demand for cement to build homes and infrastructure is surging.
But there's a problem because making cement releases huge amounts of carbon dioxide – up to 8% of the global total.
Now the boss of one cement company in India has managed to slash its carbon emissions to 40% below the global average and aims to become carbon neutral by 2040. The BBC's Rajini Vaidyanathan went to meet him.
Produced by the BBC's Stephen Hounslow, filmed by Ravi Lekhi and edited by Franz Strasser.
Climate Defenders is a five-part series highlighting people who lead the battle to protect the planet from rising temperatures.