Eat lower on the food chain (less meat).
When it comes to energy, how you choose to fill your plate is just as important as how you choose to fill your gas tank. The difference in energy needed to produce a vegetarian diet versus the average American diet is equivalent to the difference between driving a sedan versus an SUV. Even simply reducing your meat consumption will have a positive, high-magnitude impact on the environment. There are many other benefits to eating less meat as well.