Why does cement manufacturing produce carbon dioxide emissions?

Cement manufacturing is a significant source of carbon dioxide emissions, contributing to approximately 4–8 percent of global totals. These emissions arise from two primary sources during the production process:1

• Chemical Reactions: A substantial portion of CO₂ is released as an intrinsic byproduct of producing clinker. During the calcination process, raw materials—primarily limestone—are heated to high temperatures in a kiln. This heat causes the limestone to decompose, chemically expelling carbon dioxide to produce lime.12
• Energy Consumption: Additional emissions are generated by the energy-intensive nature of the manufacturing process, which typically relies on burning fossil fuels to reach the high temperatures required for clinker production.1

Because these emissions are deeply embedded in the chemical transformation of raw materials, the industry is actively researching novel cement formulations that require less clinker, alongside efforts to improve energy efficiency and implement carbon capture technologies to mitigate its impact on global warming.1