Vegan and vegetarian diets have become more popular among people as concerns for the environment continue to rise. Many individuals switch to diets that don’t contain meat in an effort to help our planet, which seems to be deteriorating at a constant level. But how valid are these efforts?

A vegan is a person who avoids any type of food that contains animal products or has animal origin. A vegetarian also avoids meat but will consume eggs and dairy products. However, it’s not only important to focus on the contents within a vegetarian or vegan diet but also how those contents affect the planet.

“What is more compelling to me as an argument in favor of vegetarianism is less the questions of what’s more efficient as a lifestyle, and instead questions about the impact of the lifestyle,”  said Dr. Tillman, a biology teacher at Stanford Online High School.

To understand the effects that vegetarian and vegan diets have on the environment, it is important to look at our greatest resources: land, water, and air.

Vegetarianism and veganism stand to have a great impact on the land that different species of animals and plants rely on to survive. A lot of land is needed for resources in the production of standard meat and dairy. Specifically, People for the Ethical Treatment of Animals, a non-profit organization in America that advocates for animals, emphasizes that “around eighty percent of all land is used for agriculture—most is used to produce crops such as corn and soybeans to feed farm animals.”

“Every trophic level loses about ninety percent of the energy that’s available to it from the next level down, so if you’ve gone two levels up…you’re going to have to grow a lot more crops to feed a bunch of cows in order to feed yourself,” said Dr. Tillman. Since a majority of animals need plants in order to survive, a lot of crops will need to be grown in order to have the amount of nutrients that are needed to produce standard meat. Plant-based diets require fewer crops to produce, as plants are in less need of more nutrients, being lower on the topic level.

However, the Humane League, an international nonprofit organization that advocates for animals, states that plant-based meat tends to have a different impact on land, using up to ninety-nine percent less land than standard meat. Also, The Vegetarian Society UK, a British charity that promotes vegetarianism, says that a vegetarian diet requires two and a half times less land than a diet that contains meat.

In terms of the amount of land that humans use to produce food, a vegan diet taxes the environment much less than a diet with meat. However, a vegetarian diet requires humans to use more land to produce dairy and egg products.

All diets, whether vegan, vegetarian, or meat-based, impact a second important resource: water. Agriculture and the production of various kinds of food require a lot of water usage. In fact, according to the Human League, agriculture is responsible for seventy percent of the global usage of water. Similar to land, a majority of water (forty-one percent) is used towards producing crops to feed livestock. Cheese, a common dairy product, requires 382 gallons of water to produce. Since a vegetarian diet consists of dairy, it can take a large amount of water to support.

A vegan diet, however, decreases this amount by up to fifty-five percent. However, this doesn’t mean that a plant-based diet does not require a lot of water. According to the Humane League, many plants require several gallons of water to produce. For example, a kilogram of mangos requires one hundred and fifty gallons of water, and a kilogram of plums requires sixty-seven gallons. Avocados, a very popular fruit that many vegans and vegetarians eat, have a water usage that ranges from thirty gallons to sixty gallons.

Vegan or vegetarian diets can also negatively affect the environment by releasing high amounts of methane, carbon dioxide, and nitrous oxide into the air from the production of plant-based products, as cited in the British Broadcasting Corporation. When humans produce fruits and vegetables, many of them use fertilizers to keep their produce from rotting.

Artificial fertilizers contribute to at least three percent of greenhouse gas emissions worldwide, while synthetic fertilizers release carbon dioxide and methane into the environment. Furthermore, the use of fertilizers, in general, brings nitrous oxide into the air.

However, choosing organic produce for your plant-based diet can have a more positive effect on the environment.

“Buying organic produce is just like a small thing you can do that’s better for the environment than using pesticides,” says a vegetarian who goes to Stanford Online High School.

But, a plant-based diet can also promote the issue of increasing the amount of carbon in the air. Mushrooms are a common meat substitute that tends to produce high amounts of carbon dioxide. Although mushrooms are usually kept in sealed rooms to control their levels of carbon dioxide, they have a tendency to produce CO2 that is forty-eight times higher than the amount of carbon dioxide that is outside.

Although the production of meat generally releases more carbon dioxide, methane, and nitrous oxide than the production of plants, plants are still able to produce high amounts of these compounds as well.

Overall, abiotic factors such as air, water, and land show that a vegetarian/vegan diet generally has a more positive effect on the environment than a diet without meat. However, it is important to take note that plant-based products can have a dramatic effect on the environment depending on how they are produced.

“Without carefully considering where our food comes from and how it is grown, our diets can have unintended consequences,” said Richard Gray, a writer from BBC Future.