For household products, carbon hides in some unexpected places.

Here’s a pop quiz, based on a recent Wall Street Journal article on the carbon footprint of various household goods. For each of the following products, guess their single biggest contribution to global warming. Consider all aspects of the product: raw materials, manufacturing, transportation, and end use. For example, one of the products examined is the Toyota Prius. Raw materials like steel, energy used in manufacturing, and transportation to dealerships are all responsible for a lot of emissions, but the biggest impact by far is — not surprisingly — the gasoline used to make it go.

Here are the other five products:

• Timberland hiking boots. Manufactured in China and sold in the U.S.
• Laundry detergent. Surprisingly, liquid detergent has a slightly smaller footprint than powdered.
• Patagonia fleece jacket. Also made in China and sold in the U.S.
• Milk. Fresh foods require an energy-intensive refrigerated supply chain to prevent spoilage.


• Six pack of beer. This fancy microbrew is made domestically, packaged in glass bottles, and delivered by truck.

OK, here are the answers:

• For the hiking boots, the chief culprit isn’t shipping. It’s leather. Cows are a huge source of methane emissions.
• The manufacturing impact of laundry detergent is overshadowed by the energy demands of your washing machine. Use cold water and line dry if you want to green your cleaning.


• For the fleece jacket, raw inputs dominate. Polyester, a petroleum product, accounts for about 71% of the item’s carbon footprint. The trip from China to the U.S. accounts for only 1%.


• For milk, the problem is, once again, cows. By themselves, cows are responsible for about 28% of milk’s carbon footprint. If you add in their feed, that figure goes up to 51%, more than the impact of packaging, processing, and transportation combined.


• For beer, the biggest culprit is in-store refrigeration. Glass for the bottles is a close second.

There isn’t a huge takeaway here. Calculating carbon emissions is complicated business, and it turns out that environmental impacts are spread widely throughout our integrated economy, often hiding in unexpected places. One of the reasons that putting a price on carbon remains an important policy goal is that it’s otherwise quite hard to know what part of the problem to attack. When carbon carries a price, the issue suddenly becomes a lot more tractable.

Otherwise, a few points do jump out from the analysis.

The first is that transportation costs just aren’t the biggest impact for most products. Patagonia could manufacture their jackets in the basement of their stores, and they would barely make a dent in their footprint. In aggregate, of course, transportation makes up a huge percentage of the world’s carbon budget, so its importance can’t be discounted. But buying local still doesn’t seem like the best lever for consumers looking to green their lifestyles.

The second is that products that consume energy in their end use tend to be wildly more environmentally harmful after they get into consumers hands than during manufacturing. In other words, if you want to reduce your carbon footprint, consider driving less.

The third is that cows remain a really big problem without an obvious solution. Methane digester projects like the ones that TerraPass funds help to decrease the impacts of agriculture, but as individuals the best lever we have is to reduce our consumption.

Adam Stein is a co-founder of TerraPass, where this post originally appeared. He writes on issues related to carbon, climate change, policy, and conservation.

Image by John Weber/WSJ.