...but now the data supports our assumptions - and then some.
The Weizmann Institute of Science recently completed a study revealing that among animal foods, beef has an environmental impact one order of magnitude higher than the other most common animal foods in the U.S. diet (dairy, eggs, poultry and pork). They looked at land use, irrigation water use, greenhouse gas emissions and nitrogen inputs. Beef production requires 28, 11, 5, and 6 times more than the average of the other four animal foods!
The method they used can now be used to compare environmental impacts of other animal and plant foods.
Here's an excerpt from the abstract of the peer-reviewed paper in the journal PNAS (Proceedings of the National Academy of Sciences):
"Livestock-based food production is an important and pervasive way humans impact the environment. It causes about one-fifth of global greenhouse gas emissions, and is the key land user and source of water pollution by nutrient overabundance. It also competes with biodiversity, and promotes species extinctions....We show that minimizing beef consumption mitigates the environmental costs of diet most effectively."