Top Carnivores

I've always kind of regretted that I never took an economics course in college.  Recently I bought a textbook on ecological economics by Michael Common and Sigrid Stagl.  The book is written primarily for students in environmental studies programs, so I was intrigued to read the authors' suggestion that it would also be an appropriate textbook for a beginning general economics course:

It is our view that all economists should appreciate that the material basis for economic activity is in the natural environment, and have some idea about how that works in relation to human interests.

It's a frequent truism that vegetarian diets have less impact on the environment than omnivorous diets, but a chart the authors include early in the book brings the point quite clearly home:

Human diets don't generally consist solely of meat.  But the chart points very effectively to the inefficiency particularly of eating meat from "top carnivores," animals that are themselves meat-eaters, like many fish.  If you're trying to cut back your own environmental impact, it turns out that your diet's diet is another thing to consider.