The (Environmental) Case Against Toast

Far more important than the white or wheat decision, is whether or not you heat your bread.

Let me tell you a story about data dreams and how they are squashed and how you learn something about the complexity of the world along the way.

When we started this project, I wanted to create an infographic that would show you all the inputs into a particular product—say, a hamburger—and then display all of the environmental outputs, like CO2 emissions and land use. And then, you'd be able to tinker with that hamburger and say, "What if I got this kind of beef?" or "What if I have a whole wheat bun?" or "What does cheese do?" and on down the line.

But think about that particular task. First, you have to track down the data for each individual ingredient. Then you have to find individual, toggleable elements that researchers have studied. As it turns out, that's not the easiest thing to find. In fact, in many cases individual data doesn't exist, and if it does, it wasn't collected or measured in the same ways. There is no canonical research on, say, how giving cows antibiotics so that they grow faster changes the energy inputs that are necessary.

We might have been able to make some squishy estimates and assumptions to get the numbers to show something, but we didn't feel comfortable proceeding down that path. Beef production is immensely complicated.

So, we stepped back and said: Well, let's start with the bun part, the bread part.

And that's when I found an excellent paper in the International Journal of Lifecycle Assessment by Namy Espinoza-Orias, Heinz Stichnothe, and Adisa Azapagic, which laid out the carbon footprint for bread, white and wheat, toasted and non-toasted. That paper formed the research basis for the infographic above (although with the changes noted below).

The paper demonstrates two really interesting things. One, there is a marginal environmental advantage to the wheat bread, but an even bigger boost comes from not toasting it. Apparently, given the relative inefficiency of toasting (which uses electric resistance heating), a major component of the carbon footprint of any given piece of bread is whether you heat it or not. So, what you see above are the extremes: toasted white bread (which is the most energy intensive) and non-toasted wheat bread (which is the least).

By far the most energy-intensive part of the process, for what it's worth, is the actual bread manufacturing part. That's all the stuff that goes into processing flour into bread, most especially the baking process. And that held steady across the white and wheat loaves.

It's worth noting that the researchers did their work for the United Kingdom's retail market. I have partially transposed their efforts, using the U.S. electrical grid's levels of pollution and American agriculture's fertilizer production profile to calculate the outputs you see above.

This was a hard decision to make, but it felt more true to the spirit of the project. And the truth is: American researchers have been less interested in the kinds of everyday analysis that we wanted to show with these graphics.

Finally, here's a quick guide to the outputs in the graphic:

  • CO2 is carbon dioxide, a major greenhouse gas.
  • CH4 is methane, another greenhouse gas.
  • Nitroxen Oxide, also known as NOX, is a pollutant that can cause to acid rain.  
  • SOX is another pollutant that can cause acid raid.
  • CO is carbon monoxide, another air pollutant.
  • Solid waste is trash, basically.