How plant-based diets can help reduce greenhouse gas emissions by 70 percent

Vegan and vegetarian diets are not just the latest trend. According to climate experts, these diets could actually help mitigate the effects of climate change.

“From a greenhouse gas standpoint and a climate standpoint, there are many advantages to a vegetarian diet and a vegan diet,” Rob Jackson, chair of the Department of Earth System Science at Stanford, said.

Transitioning towards a more plant-based diet could reduce food-related greenhouse gas emissions by up to 70 percent, according to the Proceedings of the National Academy of Sciences of the United States of America.

The agriculture industry has major anthropocentric impacts, which are impacts originating in human activities. Reduction of greenhouse gases is the most prominent effects of vegan and vegetarian diets; others include reduced destruction of rain forests, increased efficiency of food production and cleaner, more abundant water.

Reduction of greenhouse gases

Methane is generated in the guts of animals, according to Rob Jackson. The livestock sector of agriculture emits 37 percent of anthropogenic methane, which has 23 times the global warming potential of carbon dioxide, according to the Food and Agriculture Organization of the United Nation’s “Livestock’s Long Shadow” report.

The livestock sector is also responsible for 64 percent of anthropogenic ammonia emissions, which contribute to acid rain and acidification of ecosystems.

Agriculture’s effect on land

According to the Food and Agricultural Organization of the United Nations (FAO), the livestock sector is the single largest anthropogenic user of land. Livestock production accounts for 70 percent of all agricultural land and 30 percent of the land surface of the planet.

According to Jackson, the most extreme example of animal agriculture’s effect on land is tropical deforestation. Chopping down forests, and especially rain forests, releases carbon dioxide from the trees and soil into the atmosphere.

The greatest amount of deforestation is occurring in Latin America, where 70 percent of previous forested land in the Amazon is occupied by pastures, according to the FAO. About 20 percent of these pastures and rangelands have been degraded through overgrazing, compaction and erosion created by the livestock sector.

Efficiency of food production

This effect boils down to the logic that we can feed the animals the food we would have eaten or we can eat that food directly, which saves resources and reduces emissions during production.

In addition, a plant-based diet would reduce the amount of land used and the amount of food needed to be produced.

Cleaner, more abundant water

According to the FAO, freshwater shortage, scarcity and depletion are becoming an increasing world problem. Accounting for over 8 percent of global human water use, the livestock sector plays a key role in increasing water use.

In addition to water use, the livestock sector also is a huge source of water pollution. Pollutants come in the form of animal wastes, antibiotics and hormones, chemicals, fertilizers and pesticides and sediments from eroded pastures.

In the United States, livestock are responsible for an about 55 percent of erosion and sediment and 37 percent of pesticide use, according to the FAO.

"Even as we green up our energy use, which we’re doing with solar and wind, one area where we are going to massively increase both greenhouse gas emissions and water use is from our diet," Dana Hunnes, assistant professor at the UCLA Fielding School of Public Health, said.

Some argue that other dietary changes, such as purchasing only locally sourced food, can reduce one’s carbon footprint but only to some extent.

According to a Carnegie Mellon study, greenhouse gas emissions associated with food are mainly created by the production phase which contributes 83 percent of a U.S. household’s carbon footprint for food consumption. Transportation as a whole represents on 11 percent of life-cycle greenhouse gas emissions.

The authors of the study suggest that a plant-based diet can be a more effective dietary shift compared to “buying local.”

“Shifting less than one day per weeks' worth of calories from red meat and dairy products to chicken, fish, eggs or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food,” the study says.

“People are better off eating meat if they can’t get what they need from a vegan diet, but certainly in a country like the U.S. that’s not really the issue,” Jackson said.

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