Food choices affect both human and environmental health. 

Raising animals for food contributes to the cause of land degradation, air and water pollution, loss of biodiversity, global warming and water shortage.

According to a 2007 article from the Huffington Post, the United Nations says that almost one-fifth of global warming emissions come from livestock - more emissions than from all of the world's transportation combined. Animal agriculture takes up an incredible 70 percent of all agricultural land, and 30 percent of the total land surface of the planet. United Nations Report, Huffington Post

That same article gives a statistic about fossil fuels.

"Producing a calorie of meat protein means burning more than ten times as much fossil fuels -- and spewing more than ten times as much heat-trapping carbon dioxide -- as does a calorie of plant protein."

These fossil fuels are not just a result of producing the meat. This statistic takes into account transporting the animals to slaughterhouses, slaughtering them, refrigerating the carcasses and distributing the meat across the nation.

In terms of land degradation, "Animal agriculture takes up an incredible 70 percent of all agricultural land, and 30 percent of the total land surface of the planet," said the Huffington Post.

The fight against global warming most commonly involves recycling, driving a fuel-efficient vehicle, using reusable grocery bags or campaigning against mountain top removal, but often leaves out changing dietary choices.

In a book edited by David Pimentel, Cornell University professor of ecology and agriculture science, the authors discuss how many gallons of water are required to produce one pound of meat.

To produce one pound of beef requires more than 12,000 gallons of water. Researchers obtained this statistic by quantifying how much water is required to grow grain and hay and how much grain and hay a beef animal eats over about a two-year period.

Keeping this statistic in mind, the Huffington Post article points out, "Animal agriculture accounts for most of the water consumed in this country, emits two-thirds of the world's acid-rain-causing ammonia and is the world's largest source of water pollution..."