Eating vegan is more environmentally efficient than feeding the animals in a meat-based diet. Veganism also greatly reduces the wastes, pollution, and deforestation caused by mass raising of animals.
According to the U.S. Department of Agriculture, Americans lead the way in a global trend. They are eating more meat than ever before: the average American consumes nearly twice his or her weight in meat each year.
Rising prosperity has allowed people throughout the world to alter their diets to include more meat. Over the last decade, per capita consumption of beef, pork and chicken has doubled in the world's poorer nations - though it is still just one-third the level in industrial nations.
Nonetheless, global meat consumption remains highly concentrated. The United States and China, which contain 25 percent of the world's population, combine to consume 35 percent of the world's beef, over half of the world's poultry, and 65 percent of the world's pork. If Brazil and the European Union are included, this group - roughly 33 percent of the world's population consumes more than 60 percent of the world's beef, more than 70 percent of the world's poultry, and more than 80 percent of the world's pork.
Today, our planet is home to nearly 1 billion pigs, 1.3 billion cows, 1.8 billion sheep and goats, and 13.5 billion chickens - more than two chickens for each man, woman and child on the planet. We have altered vast ecosystems and devoted massive resources to support the world's burgeoning livestock herds. These animals need to be fed. They need water to survive. If they are ranged, they need land. And these animals produce enormous quantities of waste.
The ecological footprint of meat production is deep and wide, and ranges from forest destruction in Central and South America for ranching to suppression of native predators and competitors in the United States. Nearly one-quarter of the world's meat, primarily beef and mutton, depends on a natural ecosystem - rangelands. Yet, as overgrazing becomes the norm in much of the world, rangelands are being pushed beyond their limits.
Seven kilograms of grain are required to produce 1 kilogram of beef; the conversion is 4-to-1 for pork and 2-to-1 for poultry. Each kilogram of meat represents several kilograms of grain that could be consumed directly by humans, not to mention the water and farmland required growing the grain. To put this in simplified terms, the beef in a hamburger represents enough wheat to produce five loaves of bread.
Huge amounts of food - not to mention the water and farmland required growing the food - can be freed up by modest reduction in meat production. For example, if the 670 million tons of the world's grain that is fed to livestock were reduced by 10 percent, the resulting grain could feed 225 million people or to keep up with growth in the human population over the next three years.
If each American reduced his or her meat consumption by just 5 percent, roughly equivalent to eating one less dish of meat each week, enough grain would be saved to feed 25 million people - the number estimated to go hungry in the United States each day.
The massive waste produced by livestock threatens waterways worldwide. In the United States, where 130 times more animal manure is produced than human waste - 5 tons for every U.S. citizen - animal waste is the principal source of water pollution. And livestock farms are getting larger throughout the world. Iowa Sen. Tom Harkin's recent bill to reform livestock waste management estimates that one 50,000-acre hog farm under construction in Utah will produce more waste than the city of Los Angeles.
According to the Environmental Protection Agency, the world's livestock herds are the largest source of human-induced emissions of methane - a potent greenhouse gas contributing to climate change.
For those concerned about our environment, reducing meat consumption is as fundamental as reducing car use or being a conscientious recycler.