1. Identify the SUV Foods on Campus

Most understand that fighting climate change is largely about energy, but many do not realize that we literally consume a sizeable portion of our energy diet every day in the form of breakfast, lunch and dinner. While we think of meals in terms of calories instead of kilowatts or miles per gallon (MPG), lasagna has a climate change footprint that’s just as real as a water heater and probably bigger once you conduct a full environmental audit of the ingredients.

Essentially some foods are like Hummers, while others are the edible equivalents of plug-in hybrids, or even mass transit. Two foods might both deliver 300 calories, but one might do it as much as 40 times more efficiently than the other. Remember, all food is ultimately derived from sunlight, and some, like a peach from your backyard, represent a pretty direct conversion of solar energy into edible calories.

Other foods, like your typical cheeseburger, have more complicated, less efficient paths to our plate. While there are many factors, the biggest problem is with animal protein and with energy-conversion ratios. For example, typical chicken has to be fed four calories of grain for every one calorie it will give you later on the plate. For eggs it’s about 6 to 1. For both dairy products and pork, it is 14 to 1. The monster truck of the menu is grain-fed beef at 40 to 1.

With every decrease in conversion efficiency there is that much more feed grain that needs to be sown, fertilized, harvested, milled and shipped to feedlots and hog factories to produce your meal. This is partly why livestock consumes more than 80 percent of the nation’s grain production. Given that conventionally produced grains require about two pounds of fossil fuel inputs (gas for tractors and trucks, natural gas to produce nitrogen fertilizer, etc.) for every one pound harvested, you can see how your meal plan actually sits atop a substantial energy pyramid. That’s why changes to a school’s menu might deliver surprising reductions its total GHG footprint.

Some livestock are not only inefficient, but pollute as well. In this case the pollution consists of massive amounts of methane and nitrous oxide. These are serious green house gases because methane molecules trap 23 times as much heat as CO2, and 300 times as much as Nitrous Oxide. Due to their ruminant digestive system cattle are again the biggest concern because a single grain-fed cow produces up to 132 gallons of methane a day each. When multiplied by America’s 95 million head of cattle this becomes a serious problem. However, factory-style hog operations are also a significant source of emissions - largely because of their large manure lagoons. Consequently, in some calculations these emissions constitute as serious a problem for climate change as the hidden fuel bill that accompanies each hot dog or hamburger.

But before embracing roasted chicken as the climate-change savior of our meal plan, remember that even it is still only one-fourth as efficient as the fruits, vegetables and grains, where there is no intermediary animal, and no feed-to-flesh conversion loss.

The above examples do not begin to do justice to the many nuances involved in calculating the exact GHG tally for a given food, let alone the many other essential food service factors such as costs or nutritional needs. However, these examples demonstrate that schools might make surprising strides by examining what’s being served in the dining halls.

 2. What’s the Story Behind Your Potatoes?

Even if the basic components of school menus are fixed there is another significant opportunity by looking at how the food was raised or grown. Some farms, just like some factories, are more efficient and produce less waste than others.

Looking at food through a GHG lens, organic farms are one example of a way to reduce emissions. Organic farms do not use synthetic nitrogen fertilizers (which are basically a pelletized form of fossil fuel) but rather use natural inputs such as manure and nitrogen-fixing cover crops and shade trees. The use of manure is a double benefit as it converts what is otherwise a problem into a useful farm input and an aid in building healthy soil.

But whereas organic farmers sequester carbon, and put it to work, conventionally managed farms typically release CO2 from the soil every year, especially when tilling. According to an UN/UNCTAD study these soil emissions are as significant a source of GHG as the methane emissions from cattle. Another study from the Rodale Institute estimates that organic farming, if adopted nationwide, could stop the CO2 seepage and capture 500 billion pounds of CO2 annually.

No-till farming methods, even when using chemical inputs, help, too. And some farmers combine both organic and no-till practices. Similarly, the method for raising cattle can reduce otherwise large GHG footprints. Specifically, grass-fed cattle can emit as little as 50 percent of methane of corn-fed cattle, as cattle stomachs have evolved for digesting grasses, not grains.