Cement is the most widely used man-made material in existence. It is second only to water as the most-consumed resource on the planet.
But, while cement – the key ingredient in concrete – has shaped much of our built environment, it also has a massive carbon footprint.
Cement is the source of about 8% of the world’s carbon dioxide (CO2) emissions, according to think tank Chatham House.
If the cement industry were a country, it would be the third largest emitter in the world – behind China and the US. It contributes more CO2 than aviation fuel (2.5%) and is not far behind the global agriculture business (12%).
Cement industry leaders are in Poland for the UN’s climate change conference – COP24 – to discuss ways of meeting the requirements of the Paris Agreement on climate change. To do this, annual emissions from cement will need to fall by at least 16% by 2030.
So, how did our love of concrete end up endangering the planet? And what can we do about it?
In praise of concrete
As the key building material of most tower blocks, car parks, bridges and dams, concrete has, for the haters, enabled the construction of some of the world’s worst architectural eyesores.
In the UK, it helped the massive wave of post-World War Two development – much of it still dividing opinion – with several of the country’s major cities, such as Birmingham, Coventry, Hull and Portsmouth, largely defined by the concrete structures from that building push.
But concrete is also the reason some of the world’s most impressive buildings exist.
Sydney Opera House, the Lotus Temple in Delhi, the Burj Khalifa in Dubai as well as the magnificent Pantheon in Rome – boasting the largest unsupported concrete dome in the world – all owe their form to the material.
A mix of sand and gravel, a cement binder and water, concrete is so widely embraced by architects, developers and builders because it is a remarkably good construction material.
“It’s affordable, you can produce it almost anywhere and it has all the right structural qualities that you want to build with for a durable building or for infrastructure,” explains Felix Preston, deputy research director at the Energy, Environment and Resources Department at Chatham House.