Strictly speaking, the term “meat-eating environmentalist” is oxymoronic. Editors at World Watch report that “The human appetite for animal flesh is a driving force behind virtually every major category of environmental damage now threatening the human future–deforestation, erosion, fresh water scarcity, air and water pollution, climate change, biodiversity loss, social injustice, destabilization of communities, and the spread of disease.” Worldwide meat consumption is at an all-time high. It quadrupled in the past 50 years and will double again by 2050 unless we change how we eat.

Cows, more than cars, are the primary offender behind global warming. According to a United Nations Food and Agricultural Organization report, cattle emit 18 percent of greenhouse gases, more than all transportation combined. Add in other common livestock, and more than a third of all raw materials and fossil fuels consumed in the United States are used in animal production.

University of Chicago geophysicists conclude that switching from a “standard American diet” to a vegetarian menu “does more to fight global warming than switching from a gas-guzzling SUV to a fuel-efficient hybrid.” Of course, we can do both. Scientists point out that being a vegetarian is like driving a mid-sized car instead of a gas hog, and a vegan diet is the equivalent of riding a bicycle or walking. It’s a fact. Not eating meat is the single most important thing we can do to save the planet.

Every vegetarian saves an acre of trees each year, literally protecting “the lungs of the Earth.” WorldWatch estimates that one 400-calorie hamburger patty chews up 55 square feet of tropical forest, former home to 165 pounds of native plant and animal life. Forty percent of Central America’s rainforest has been cleared for cattle pasture in the past 40 years. Likewise, “cattle ranchers are making mincemeat out of Brazil’s Amazon rainforests,” reports the Center for International Forestry Research. Vegfam calculates that a 10-acre farm can support 60 people growing soybeans, 24 growing wheat, 10 growing corn, or two producing cattle.

Vegetarian Resource Group nutrition counselors say that humans need to consume just two to 10 percent of daily calories as protein. Alternative sources include potatoes, whole wheat bread, rice, broccoli, spinach, almonds, peas, chickpeas, peanut butter, tofu, soymilk, lentils and kale.