- "Biophilia" by E.O. Wilson
- "Diet for a Small Planet" by Frances Moore Lappe
- "Recipes for a Small Planet" by Ellen Buchman Ewald
What we eat has a tremendous effect on the world. How? Because of the chain of events that brings the food to us. Food is grown, harvested, shipped, packaged, and sold. At each step, actions are taken on our behalf and these actions change the world. Consequently, if you change what you eat you will change the world.
The least destructive diet is vegetarian (at least given the state of meat production within the agribusiness system), particularly when the food consumed is organic and locally produced (but do the best you can). This is not because of the suffering that animals may go through, but because of the environmental and social consequences. For instance, it takes 21 pounds of vegetable protein to produce a pound of meat protein. That's a lot of grain. Sometimes ground is cleared to make room to plant grain; sometimes cattle are allowed to graze on wild grasses. Fast food burgers were directly responsible for clearing virgin rainforest for this purpose. Addtionally, chemical fertilizers and pesticides are generally used to grow the crops as well, and those chemicals eventually wind up in animals and the water supply. If we consume the grain directly, the requirements are much less than 21 pounds per meal, so the need for fertilizer and pesticides is also decreased substantially.
The herds of animals introduce their own problems. There are places in the world that were formerly very green and full of life. But due to grazing, they have become barren and rocky. It starts with animals that graze at a fairly rough level, like cows, and as the land deteriorates, more and more hardy animals are introduced until eventually the land has lost its ability to produce.
And now there's a very modern problem, which has arisen over the last 50 years. Animals have been receiving antibiotics. The target bacteria are becoming resistant, which affects not just the animals (or investments) we're trying to protect but also us as we run out of effective antibiotics.
All the above only considers the environmental consequences, but the social consequences are also great. As farmland is devoted to raising herd animals, it becomes inaccessible to local people. This causes migration, among other things. In large enough numbers, migration can be very disruptive to society. People who may have been self-sufficient now require help to survive in new surroundings, perhaps with skills not useful in those surroundings.
If we also consider the way the food is delivered, there are further social consequences. Fast food, for instance, has changed the US and now the world. Not just in the obvious way, with one restaurant on every corner, but in more subtle ways such as low wage, non-union, low skill jobs.
The list of effects is endless. So the bottom line is If you want to decrease suffering in the world, think about what you eat and act accordingly.