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More than three-quarters of the world’s poor rely on agriculture to earn a living.

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The Stuff of Life

Reduce, reuse, retool

How we can cut carbon emissions by using less stuff.


Last week in Paris I got to be part of a big announcement about energy and climate. Several governments and private investors came together to make major commitments for funding clean-energy research. This is a big focus for me, because providing more energy for the poor is essential for fighting poverty, and because switching to clean energy is essential for stopping climate change.

But energy is not the only factor that affects how much carbon we pump into the atmosphere. I recently read an excellent book about another key factor: how we make stuff. The book is called Sustainable Materials With Both Eyes Open, by a team at the University of Cambridge led by researchers Julian Allwood and Jonathan Cullen. (You can download it free on their site.) Although the book is probably too detailed for most general readers—its 350 pages are filled with dense diagrams and a lot of numbers—the authors’ conclusions are well worth understanding.

They focus on the five materials that account for more than half of the world’s industrial carbon emissions (steel, cement, paper, plastic, and aluminum). As I’ve mentioned before, it’s impossible to imagine a modern world without these materials. Every year for example we produce more than 440 pounds of steel for every person on Earth, nearly half of which goes into buildings. And demand for all these materials will roughly double by 2050, as the world’s population grows and more people join the global middle class. Yet producing this stuff contributes significantly to climate change—and also creates other risks like reducing the supply of drinkable water and land that could be used for growing food.

The question boils down to this: How can we meet the growing demand for materials without destroying the environment?

The authors start by asking whether we can get a big enough reduction in greenhouse gases simply by producing these materials more efficiently. (They’re looking for a 50 percent reduction. I think we need to get to at least 80 percent by 2050 and eventually 100 percent, but either way you’re talking about a big cut.) Unfortunately, efficiency gains on their own won’t be enough. The problem is that demand is going to double by mid-century. Suppose you make widgets, and you invent a way to cut your carbon emissions by 30 percent per widget. If you start making twice as many widgets, your overall emissions will still go up by 40 percent. The authors call this approach—thinking only about efficiency gains—looking “with one eye open.”

How do you look with both eyes open? By also studying how you could use less material to begin with, make products that last longer, reuse or recycle them, or avoid using the service the material provides. The authors argue that by looking with both eyes open—both using less stuff, and making stuff more efficiently—it should be possible to cut emissions in half without asking people to make big sacrifices.

I was surprised to learn how many opportunities there are to reduce overall use of materials. For example, although I knew about basic recycling efforts like collecting aluminum cans at the office, I hadn’t realized how much reuse is possible at an industrial level. The authors argue that when a product—say, a building or car—is discarded, the materials in it are often still usable. (Reusing is much better than recycling, because recycling takes yet more energy.) If you throw out your old refrigerator, the steel is probably still in good condition. So is the steel in old buildings, as long as there hasn’t been a fire or earthquake. It could be reused, if you could take it apart easily and get it to someone who wanted that shape.

But matching up buyers and sellers is hard. Who has the time to look around for someone who might want pieces of your old refrigerator? This is an area where technology can help. We can put digital stamps on products so we can track their history, and digital markets can match supply with demand. There are other intriguing ideas too, like finding ways to make buildings that are dismantled instead of demolished, so we could reuse more of the stuff they’re made of.

Although the book isn’t aimed at a general audience, the authors keep things lively with colorful illustrations and funny analogies. I’ve read other books about steel, but none of them featured a photo of the Carhenge exhibit in Nebraska. I’ve read a lot of books about physics, but I don’t remember seeing such an extended riff on how atoms act like people dancing in a nightclub.

The book’s message is clear and convincing: We can’t go on using materials the way we have been for the past 150 years, but fortunately, we don’t have to. We can meet the world’s growing need for the stuff of modern life, avoid the worst effects of climate change, and preserve the environment for future generations.