Opinion: Which diet will help save our planet: climatarian, flexitarian, vegetarian or vegan?
12 August 2022
Writing in The Conversation, Professor Mark Maslin (UCL Geography) explores which “climate-friendly” diet is the most environmentally sustainable, and explains why deciding which one to choose is not as simple as we might expect.
The food we consume has a massive impact on our planet. Agriculture takes up half the habitable land on Earth, destroys forests and other ecosystems and produces a quarter of the world’s greenhouse gas emissions. Meat and dairy specifically accounts for around 14.5% of global greenhouse gas emissions.
So changing what we eat can help reduce carbon emissions and promote sustainable farming. But there are several “climate-friendly” diets to choose from. The best known are the completely plant-based vegan diet, the vegetarian diet, which also allows eggs and dairy, and the pescetarian diet, which also allows seafood.
There are also “flexitarian” diets, where three quarters of meat and dairy is replaced by plant-based food, or the Mediterranean diet which allows moderate amounts of poultry, pork, lamb and beef. Deciding which diet to choose is not as simple as you might expect.
Let us start with a new fad: the climatarian diet. One version was created by the not-for-profit organisation Climates Network, which says this diet is healthy, climate friendly and nature friendly. According to the publicity “with a simple diet shift you can save a tonne of CO₂ equivalents per person per year” (“equivalents” just means methane and other greenhouse gases are factored in alongside carbon dioxide).
Sounds great, but the diet still allows you to eat meat and other high emission foods such as pork, poultry, fish, dairy products and eggs. So this is just a newer version of the “climate carnivore” diet except followers are encouraged to switch as much red meat (beef, lamb, pork, veal and venison) as possible to other meats and fish.
The diet does, however, encourage you to cut down on meat overall and to choose high-welfare and local meat where possible, while avoiding food waste and choosing seasonal, local foods.
So saving a tonne of carbon dioxide is great but switching to vegetarianism or veganism can save even more. A western standard meat-based diet produces about 7.2 kilograms of CO₂ equivalent per day, while a vegetarian diet produces 3.8 kg and a vegan diet 2.9 kg. If the whole world went vegan it would save nearly 8 billion tonnes CO₂e while even a switch to the Mediterranean diet would still save 3 billion tonnes. That is a saving of between 60% and 20% of all food emissions as which are currently at 13.7 billion tonnes of CO₂e a year.
To save our planet, we must also consider both water and land usage. Beef, for instance, needs about 15,000 litres of water per kilo.
Some vegetarian or vegan foods like avocados and almonds also have a huge water footprint, but overall a plant-based diet has about half the water consumption of a standard meat-based diet.