It seems that having the lowest carbon footprint as a vegan isn’t guaranteed – it depends on what you eat. What is clear from our experiment (and more importantly, from rigorous scientific research) is that on average a plant-based diet has significantly fewer emissions. Eating large amounts of meat, especially beef, is a sure way to increase your emissions many times over.
The tweaks to our diets that would result in the greatest fall in emissions were:
- Reducing animal products – eating fewer of them, or replacing with a plant-based alternative
- Focusing on what you eat rather than food miles
- Cooking efficiently, and saving ovens for special occasions rather than everyday use
- Batch cooking to prepare food using a fraction of the energy
- Avoiding food waste, through careful planning and creative cooking
And what did our researchers think of our experiment? “The biggest surprise for me is how many different foods we all eat in a day,” says Bridle. “It’s complicated for anyone to figure out for themselves what their food climate impact is. But despite this, the usual trends emerged – that the most important factors are usually the quantities of each animal product, and any long cooking times. I was impressed with your honesty about the food waste, and surprised how much the waste added to the total climate impact.”
For Lait, it was how quickly decisions about food start to add up. “I’ve done lots of calculations on individual meals or school menus,” says Lait. “But seeing over a couple of weeks what a difference your diet makes – it really reminded me how powerful our food choices can be in affecting climate change. We have the opportunity to make these powerful decisions several times a day.”
The world’s food system is immensely complex, and emissions come from many different sources. Many of these happen before we even pick food off a shelf: land use, farming, packaging and transport, and pre-retail waste among them. But a few simple rules of thumb can be helpful for finding our way through this maze, to make sure our food choices really do help curb emissions.
And, while our experiment has been illuminating, the scale of the challenge of food emissions is deeply sobering. One 2020 review found that even if we had stopped burning fossil fuels immediately, humanity still wouldn’t be able to meet the 1.5C limit for global warming set out by the Paris Agreement. Our emissions from food are so high, they alone could tip us over this threshold. At 2C warming, coral reefs are almost extinct – more than 99% are expected to vanish – small islands and coastal communities will disappear, and the Arctic will have an ice-free summer once every 10 years.
So for now, our vegan will continue avoiding animal products, feeling rather pleased with herself, and our vegetarian will fork her compost with renewed determination.
This article was produced with additional research by Zubaidah Abdul Jalil, Content Producer at BBC News
Sarah Bridle is the author of Food and Climate Change: Without the Hot Air, published by UIT Cambridge.
Rebecca Lait is a freelance sustainability researcher based in the UK
Zaria Gorvett is a Senior Journalist at BBC Future, and tweets at @ZariaGorvett
Martha Henriques is Editor of BBC Future Planet, and tweets at @Martha_Rosamund
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