SOURCE: The Guardian
DATE: February 25, 2019
SNIP: In the time it takes you to read this sentence, the global building industry will have poured more than 19,000 bathtubs of concrete. By the time you are halfway through this article, the volume would fill the Albert Hall and spill out into Hyde Park. In a day it would be almost the size of China’s Three Gorges Dam. In a single year, there is enough to patio over every hill, dale, nook and cranny in England.
After water, concrete is the most widely used substance on Earth. If the cement industry were a country, it would be the third largest carbon dioxide emitter in the world with up to 2.8bn tonnes, surpassed only by China and the US.
Taking in all stages of production, concrete is said to be responsible for 4-8% of the world’s CO2. Among materials, only coal, oil and gas are a greater source of greenhouse gases. Half of concrete’s CO2 emissions are created during the manufacture of clinker, the most-energy intensive part of the cement-making process.
But other environmental impacts are far less well understood. Concrete is a thirsty behemoth, sucking up almost a 10th of the world’s industrial water use. This often strains supplies for drinking and irrigation, because 75% of this consumption is in drought and water-stressed regions. In cities, concrete also adds to the heat-island effect by absorbing the warmth of the sun and trapping gases from car exhausts and air-conditioner units – though it is, at least, better than darker asphalt.
Limestone quarries and cement factories are also often pollution sources, along with the trucks that ferry materials between them and building sites. At this scale, even the acquisition of sand can be catastrophic – destroying so many of the world’s beaches and river courses that this form of mining is now increasingly run by organised crime gangs and associated with murderous violence.
This touches on the most severe, but least understood, impact of concrete, which is that it destroys natural infrastructure without replacing the ecological functions that humanity depends on for fertilisation, pollination, flood control, oxygen production and water purification.
[Read the whole fascinating article about concrete at The Guardian].