Reprinted from the Los Angeles Times, January 6, 2017
"I recently followed a drone through the ruined Syrian city of Aleppo, courtesy of YouTube. The destruction was sobering, to say the least. The camera glided by exploded apartment buildings and streets piled with rubble, block after city block. The political situation in Syria is contemptible, the impact of war on human lives horrendously tragic, all silently conveyed in the aftermath captured on video. It also captured something more subtle, something that could easily go unnoticed: Aleppo was built almost entirely of concrete. Concrete dominated every shot. That observation might seem strange, but bear with me.
Of all the multitudinous things we humans manufacture, concrete is among the most common. To make it, we dynamite limestone out of the Earth’s crust and cook it at 2,700 degrees Fahrenheit. This produces cement, the adhesive component of concrete. Heat changes limestone’s molecular structure, making it reactive with water, so a bag of gray powder and some aggregate, like rock or sand, can be conveniently turned back into a strong solid of any shape with water from a garden hose.
The amount of fossil fuel required to make cement is astonishing: Producing 1 ton of concrete, about a cubic yard, uses the equivalent of 400 pounds of coal. The concrete industry accounts for 5% of the world’s greenhouse gas emissions. When I see all the concrete used to build Aleppo, I think of what has been released into the air to produce it."
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Image: An undated photo made available by the Russian Defense Ministry on Jan. 2 shows a portion of eastern Aleppo, Syria. (EPA) via the Los Angeles Times.
Sam Stier is director of the Center for Learning With Nature and teaches science and sustainable design at Otis College of Art and Design.