Veganism and Climate Change

Veganism and climate change concerns the relationship between diets that exclude animal products and the mitigation of global warming. A substantial body of research indicates that animal products, particularly ruminant meat and dairy, have much higher greenhouse gas emissions than most plant foods, and that dietary shifts toward plant-based foods could significantly reduce emissions from the food system. Climate concerns have become an increasingly prominent motivation for adopting veganism.

The food system’s contribution

The food system is a major source of greenhouse gas emissions. A 2018 study by Joseph Poore and Thomas Nemecek published in Science estimated that food production accounts for around 26% of global anthropogenic emissions, with animal products responsible for more than half of that share despite providing a minority of the world’s calories and protein. The Food and Agriculture Organization of the United Nations (FAO) has estimated livestock’s contribution at between roughly 12% and 14.5% of human-caused emissions in its more recent assessments. These estimates are discussed in more detail in environmental impact of animal agriculture.

A 2020 study by Michael Clark and colleagues, also published in Science, concluded that even if fossil fuel emissions were halted immediately, emissions from the global food system alone could make it difficult to meet the Paris Agreement target of limiting warming to 1.5°C, and identified the adoption of plant-rich diets as one of the main options for reducing those emissions.

Why animal products have higher emissions

Several factors explain the higher emissions associated with animal products:

• Enteric methane. Ruminants such as cattle, sheep and goats produce methane during digestion. According to the IPCC’s Sixth Assessment Report, methane has a warming effect roughly 80 times that of carbon dioxide over 20 years and roughly 27–30 times over 100 years, although it remains in the atmosphere for a much shorter time.
• Feed conversion. Animals convert only a portion of the energy and protein in their feed into edible products, so more crops and land are needed per unit of food.
• Land-use change. Clearing forests and other ecosystems for pasture and feed crops releases stored carbon.
• Manure and fertiliser. These release methane and nitrous oxide, another potent greenhouse gas.

Estimates of dietary impact

Research comparing diets has consistently found lower emissions for plant-based diets, although exact figures depend on the methods and assumptions used:

1. Poore and Nemecek (2018) estimated that a global shift to diets excluding animal products could reduce food-related greenhouse gas emissions by about 49% and agricultural land use by about 76%.
2. A 2016 modelling study by Marco Springmann and colleagues, published in Proceedings of the National Academy of Sciences, projected that a global vegan diet could reduce food-related emissions by around 70% by 2050, compared with a reference scenario.
3. A 2023 study by Peter Scarborough and colleagues, published in Nature Food and based on dietary data from around 55,000 people in the United Kingdom, found that the greenhouse gas emissions of vegan diets were about a quarter of those of diets high in meat.

Policy recognition

The Intergovernmental Panel on Climate Change (IPCC), in its 2019 Special Report on Climate Change and Land, identified balanced diets featuring plant-based foods as a major opportunity for climate change mitigation, while noting co-benefits for health. The Global Methane Pledge, launched at the COP26 climate conference in 2021, committed participating countries to collectively reduce methane emissions by at least 30% from 2020 levels by 2030, although it does not specifically require changes in diet.

Few governments have adopted explicit policies to reduce consumption of animal products, and the topic remains politically sensitive in many countries with large livestock sectors.

Carbon opportunity cost

Some researchers argue that the climate benefit of reducing animal agriculture is larger than direct emissions figures suggest, because land freed from grazing and feed production could be restored to forests and other ecosystems that absorb carbon dioxide. Estimates of this potential vary widely and depend on assumptions about land restoration.

Debates and limitations

Discussion of veganism and climate change includes several areas of disagreement:

• Methane accounting. Some scientists argue that because methane is short-lived, standard metrics can overstate the long-term warming effect of stable livestock herds; others note that cutting methane offers rapid near-term cooling benefits.
• Grazing systems. Claims that certain grazing practices can offset emissions through soil carbon storage are contested.
• Individual versus systemic change. Some commentators emphasise that individual dietary choices are only one part of climate action alongside energy, transport and policy changes.
• Processed alternatives. The emissions of meat and dairy alternatives are generally reported to be much lower than those of the animal products they replace, though they vary by product.

See also

• Environmental Impact of Animal Agriculture
• Plant-Based Milks
• How to Go Vegan