Adopting A Vegetarian Diet Can Significantly Reduce Individual Greenhouse Gas Emissions

Collectively, humans make billions of decisions every day that drive climate change, the result of greenhouse gas (GHG) accumulation in the atmosphere. While it can take decades for new, climate-friendly national policies and major energy transformations to change the world’s well-established infrastructures and industries, individuals’ behavioral shifts alone might produce a more rapid and widespread impact. Scientists from Sweden and Canada considered a wide range of individual lifestyle choices and calculated their potential to reduce individual GHG emissions in developed countries.

The scientists developed a method to calculate the estimated savings in GHG emissions. All actions were framed so that they would result in the maximum possible effect. For instance, recycling was framed as recycling continually for a year, the “plant-based diet” was framed as one devoid of all meat, and purchasing renewable energy was defined as purchasing all possible household energy from renewable sources for a year straight. The researchers examined an impressive total of 148 climate-impact scenarios of individual behaviors across ten countries within the developed world.

The results might shock the passionate LED light bulb advocates among us, as the researchers recommend the following four widely applicable highest-impact actions:

1. Having one fewer child reduces CO₂-equivalent GHG emissions by a staggering 58.6 metric tons per year, on average, for developed countries.
2. Living car-free amounts to 2.4 metric tons of CO₂ equivalent saved per year.
3. Avoiding airplane travel amounts to an average of 1.6 metric tons of CO₂ equivalent saved per one return transatlantic flight.
4. Eating a vegetarian diet amounts to 0.8 metric tons of CO₂ equivalent saved per year.

These actions are reported to have much greater potential to reduce individual GHG emissions than commonly promoted strategies such as meticulous recycling and upgrading household light bulbs, which are four and eight times less effective than a vegetarian diet, respectively. Among the highly impactful actions they assessed, the authors considered including the impacts of not having a companion dog and purchasing green energy, but the environmental effects of dog companionship are not well studied yet (however, do read our summary about the environmental impact of pet foods), and green-energy purchases require an established infrastructure and thus are limited geographically.

To illustrate the implications of their findings, the researchers urge us to remember that we must reach per capita emissions of 2.1 metric tons of CO₂-equivalent annual GHG emissions by 2050 to keep global warming below the critical limit of 2°C. The researchers estimate that an individual who eats meat and takes one return transatlantic flight per year emits 2.4 metric tons of CO₂-equivalent GHG through these actions alone, flying far above his or her personal carbon budget. A drastic reduction in personal GHG emissions could help meet our climate goals, particularly since technological advances may not progress in time to reduce emissions from these two actions, even by 2050. On the upside, previous research suggests that the willingness of individuals to eat less meat increases with the perceived effectiveness of this action.

The need for increased awareness regarding effective and sustainable dietary changes is clear. However, better educational tactics must be used to penetrate cultural and structural norms, as even knowledgeable and willing individuals may not reduce meat intake or adopt other high-impact actions. Present-day examples include the ubiquitous cultural associations between meat and wealth, status, and luxury. Meat consumption is 750% higher per capita in the richest 15 nations than in the poorest 24.

When analyzing recommendations presented in textbooks, the authors found that they overwhelmingly focused on moderate- and low-impact actions, whereas the top four high-impact recommendations were mentioned only eight times—a mere 4% of the total textbook recommendations. The textbooks presented vegetarianism as a moderate-impact action, even though a completely plant-based diet can be 2 to 4.7 times more effective at reducing GHG emissions than simply decreasing meat intake. Recycling and energy conservation, on the other hand, were frequently recommended in the textbooks.

The researchers warn that even though some high-impact actions are politically unpopular, this cannot justify promoting lower-impact actions at the expense of highly impactful ones. For example, the authors mention that one textbook recommended switching from plastic bags to reusable shopping bags to save 5 kg of CO₂ per year. This is estimated to be less than 1% as effective as a year without eating meat. By focusing on lower-impact actions, the textbook authors may be using the “foot-in-the-door” technique, where easy-to-perform and frequent actions are said to motivate individuals to take on bigger actions later. However, evidence of this technique’s effect is mixed. Meanwhile, promising research indicates that high-commitment, pro-social behaviors might be more likely to motivate individuals.

The results of the study reveal that educational and governmental guidelines currently don’t focus on high-impact actions for reducing GHG emissions. The authors claim that this leads to a knowledge gap between official recommendations and individuals who are willing to align their behavior with climate targets. In contrast to previous research (which emphasized incremental behavioral changes that require minimal effort from individuals), the researchers propose empowering the public to focus on changing behaviors that can most effectively reduce personal emissions. By providing accurate guidelines, the public—especially “catalytic” individuals like adolescents—could become a major driving force in reaching the proposed 2°C climate target.

Animal advocates will surely appreciate the benefits of having yet another study that backs vegetarianism’s environmental relevance. Moreover, in the light of the ineffective educational and governmental recommendations currently in place, it’s of utmost importance that animal advocates and conservationists continue spreading accurate information to help educate the public.