Eat vegetables, save energy.

In addition to driving hybrid cars and installing solar panels on their homes, consumers may have another tool in the fight against global warming. In a study published in the April 12 issue of Earth Interactions, researchers at the University of Chicago conclude that eating less red meat and fish and consuming more vegetables can help lower greenhouse gas emissions.

Pamela Martin and Gidon Eshel compared the fossil energy requirements of five different diets: those based on red meat, poultry, and fish; a vegetarian diet; and what they call the "mean American diet," consisting of roughly 70 percent plant-based foods and 30 percent meat, eggs, dairy, and fish. Using U.S. Department of Agriculture statistics and other data, they calculated the total energy needed to grow, harvest, transport, and cook the foods. (According to the U.S. Department of Energy, food production accounts for 10 percent of all U.S. energy use.)

[ILLUSTRATION OMITTED]

The researchers found that the vegetarian diet was the most energy efficient. In other words, it takes far less energy--from the fossil fuels used to fertilize and harvest crops, to the energy required to process feed for livestock, to the gas used to transport food to the grocery store--to feed vegans and vegetarians than meat eaters. Surprisingly, the study also found that eating more fish and less red meat, a shift that many consumers make for health reasons, doesn't necessarily help reduce energy consumption. Eating tuna, swordfish, shark, and other deep-ocean fish requires labor-intensive harvesting and long-distance transport, making the seafood highly energy inefficient. Fish harvested closer to shore, on the other hand, take less energy to catch, process, and ship.

The average animal-based diet in the United States (the so-called "mean American diet") generates about 1.5 metric tons of carbon dioxide more per person per year than a plant-based diet yielding the same amount of calories, according to the researchers--roughly the emissions difference between driving a gas-guzzling SUV and a compact car.