Here's a mind stretcher for you. In Have You Hugged a Concrete Pillar Today? Bill Gates references his favorite historian Vaclav Smil, who wrote Making the Modern World: Materials and Dematerialization, who informs us of this fact.

Infographic: Comparing China's Cement Usage in the 20th and 21st Centuries - Making the Modern World by Vaclav Smil, Book Review | GatesNotes.com The Blog of Bill Gates
Gates tells us that Vaclav Smil thinks cement is the most important man-made material. My point is just to help stretch our minds and help make us smarter. Plus I needed a text bridge to get us to the main feature of the post the upcoming video of Vaclav Smil provoking clever thoughts against a back drop of some amazing super modern Chinese shopping malls and cities.
He argues that the most important man-made material is concrete, both in terms of the amount we produce each year and the total mass we’ve laid down. Concrete is the foundation (literally) for the massive expansion of urban areas of the past several decades, which has been a big factor in cutting the rate of extreme poverty in half since 1990. In 1950, the world made roughly as much steel as cement (a key ingredient in concrete); by 2010, steel production had grown by a factor of 8, but cement had gone up by a factor of 25. This animated GIF shows the dramatic transformation of Shanghai since 1987. Most of what you’re seeing in that picture is concrete, steel, and glass.
This isn’t just idle curiosity. It might seem mundane, but the issue of materials—how much we use and how much we need—is key to helping the world’s poorest people improve their lives. Think of the amazing increase in quality of life that we saw in the United States and other rich countries in the past 100 years. We want most of that miracle to take place for all of humanity over the next 50 years. As more people join the global middle class, they will need affordable clean energy. They will want to eat more meat. And they will need more materials: steel to make cars and refrigerators; concrete for roads and runways; copper wiring for telecommunications.
Instead he’s interested in the materials we use to meet the demands of modern life. Can we make enough steel for all those cars and enough concrete for all those roads? What are the risks if we do? In other words, can we bring billions of people out of poverty without destroying the environment?
Vaclav Smil: Making the Modern World
Bill Gates expresses surprise that the oceans are not getting more attention compared to other environmental problems. Gates cites Smil who cites estimates that we dump 6.4 million tons of plastic litter into the oceans each year.
What surprises me about both of these "global philosophers" who are taking sweeping 100 year scans of our global consumption of materials, is that although they ask the right questions, they seem to glibly assume we will have plenty enough materials for the people of China, these rest of South East Asia, Africa, and Latin America to rise to the same level of material standards of living as the U.S. and Europe over the next 60 years without much trouble.
Most futurists and global thinkers I'm familiar with would take issue with that assumption, and would at the very least want to hear more than a sentence and waive of the hand at the issue. Bill Gates' blog and this video set the issue up quickly and slickly. Perhaps, they express greater concern in the book which I believe I shall read.