Update: The researchers did not find that vegetarians or vegetarianism are harmful to the environment, or that producing vegetables is more harmful to the environment than producing meat.
What they found, in light of the data they examined, is that producing some vegetables and other foods results in high use of natural resources – and that eating more of those foods (as recommended for health by the USDA) in two particular scenarios results in higher energy use, blue water footprint and greenhouse gas emissions.
Other research suggests that eating less meat is a good thing for the environment. One previous study found that following a lacto-ovo vegetarian diet (no meat, fish, or poultry) would result in a 33 percent decrease in greenhouse gas emissions, and vegan diets go even further, with a 53 percent decrease in emissions.