Plant-based diets: are they truly sustainable?

Plant-based diets: are they truly sustainable?

What is the most significant driver change to our global ecosystems?

Food production.

Yet we need food to survive, so is there a way we can make our diets more sustainable?

Time and time again we are told that we must reduce our meat and dairy consumption, but plants need water, land and nutrients too, don’t they? What about air miles and deforestation? Are plant-based diets always better?

Recently, I have been asking myself these questions as, just like you, I want to do the right thing. However when it comes to sustainability, the ‘right’ thing is sometimes hard to find. To decide whether or not I should stop eating meat and dairy, I have had to dive into academic literature and identify reliable sources in order to come up with my own conclusion. I will now share with you my thoughts and some powerful facts in the literature.

  • Almost 80% of greenhouse gases from agriculture come from livestock production (IIED and Oxfam, 2009).
  • In general, animal products, both meat and dairy, cause higher emissions and need more resources than plant-based alternatives (UNEP, 2010).

 

Figure 1, Bar chart comparing the greenhouse gas emissions associated with different protein sources

(Poore and Nemecek, 2018, cited in Guibourg and Briggs, 2019).

 

Figure 1 shows how plant-based diets are associated with smaller greenhouse gas emissions. This pattern of reduced impact from meat to vegetarian to vegan protein sources is similarly repeated when comparing the impact on land use, water scarcity, land acidification and eutrophication (a process which kills aquatic and marine biodiversity).

Therefore, by reducing your meat and dairy consumption, you can massively reduce your contribution to climate change and environmental degradation.

  • Eating less meat will reduce our carbon emissions (IPCC, 2018).
  • More than half of the world’s crops are used to feed animals, not people. Fewer calories would be wasted if people ate these crops directly and so, plant-based diets are more efficient (UNEP, 2010).
  • As well as being healthier for the planet, a plant-based diet could benefit both your health and mine. This is because we are likely to eat more vitamins and minerals and less processed meat, which is carcinogenic (World Health Organisation, 2015). What could be better than protecting our health at the same time as planetary health?

Something which always bugged me though, was the claim that plant-based diets have lower greenhouse gas emissions:

It has long been known that the production of meat produced more greenhouse gases than the production of plant-based alternatives. However, these arguments did not account for the transportation of different foods; Europe has an unsuitable climate for most plant-based alternatives like nuts, beans and tofu, yet it is perfect for beef, lamb, pork, chicken and dairy farming.

So, switching to a plant-based protein source would result in more foods having to be imported from other countries, resulting in more greenhouse gases being emitted in food transportation.

Also, production in other countries may stimulate the deforestation of tropical rainforests, such as Indonesia, leading to major losses in carbon sinks and biodiversity.

However, a study published in Science, one of the world’s leading academic journals, calculated that the emissions associated with animal products; from production, to transportation to retail losses, vastly outweighed the emissions associated with alternatives. Therefore, in the grand scheme of things, it is more sustainable to eat a plant-based diet than to buy local meat and dairy.

Despite all this, it is worth remembering that plant-based diets can still have their faults. Some farms may be sneaky and deforest land unnecessarily, since there is already sufficient land to feed the 9.8bn people expected to share this planet in 2050.

So when I make more sustainable changes in my diet, how can I be sure that my choices don’t contribute to deforestation?

Research. Before buying a product, ask yourself, “is this sustainable?” Does this brand have a “no deforestation” policy? If not, don’t buy it! If you are not assured by promises of sustainable agriculture, you use your power to make an influential choice over the future of this planet.

Rice is also a weird one, since its effect on climate change is almost 8 times greater than the potato, and potentially worse than foods like beans, nuts and tofu! Clearly, there are cultural concerns about cutting out rice, since it has been fundamental to many Eastern diets throughout history. However if you can cut down or eliminate your rice consumption, you’re on to a winner with the environment.

 

Figure 2, Bar chart comparing the greenhouse gas emissions associated with different starches

(Poore and Nemecek, 2018, cited in Guibourg and Briggs, 2019).

 

Of course, changing one’s diet is a very personal thing and it may feel, or actually be, impossible to become fully vegan due to cultural or health reasons.

This has led to the recognition of the reducetarian; someone who strives to eat less meat. This term is inclusive of vegans and vegetarians. However, if you are unable to completely eradicate your meat and dairy consumption, you can still become a reducetarian by cutting down your meat consumption to say a few days a week and participating in ‘Meatless Mondays,’ for example. I like to use this term since I eat a vegan diet, but am still in the process of moving away from eating fish.

One of the first, most impactful decisions I made when transitioning to a plant-based diet in my teenage years was to eliminate my beef consumption. I was struggling to persuade my parents to let me cut out meat entirely, but they allowed me to stop eating high-impact meats. So it was no to beef and yes to more chicken! By substituting a portion of beef with chicken, your contribution to greenhouse gas emissions would fall by 82%! Also, 29 fewer tennis courts worth of land would have gone into producing that portion of chicken, showing just how much you can make a difference even as a meat eater.

Nevertheless, it is clear to see that the more your diet is plant-based, the more sustainable it is. So, I eventually stopped eating meat and dairy.

 

Figure 3, Bar chart comparing the environmental impact of different varieties of milk

(Poore and Nemecek, 2018, cited in Guibourg and Briggs, 2019).

 

However, sustainable diets are also about eating less processed and packaged foods, because these foods are healthier and are less energy-intensive. Thus, no matter how much of a reducetarian you are, your lifestyle can become more sustainable by making simple decisions to eat more whole foods and refusing to buy things wrapped in excessive packaging. Instead, why not bring your own bags and buy loose items?

Shifting towards a plant-based diet is necessary for sustainability. However, there are political and cultural challenges. By actively making the choice to change your diet, you can join the movement towards creating a safer, more sustainable planet for us all.

References:

Guibourg, C., Briggs, H. 2019. Climate change: Which vegan milk is best?. The Guardian. [Online]. 22 February. [Accessed 23 July 2019]. Available from: https://www.bbc.co.uk/news/science-environment-46654042

IIED and Oxfam. 2009. Fair Food Miles: Recharting the food miles map. London: International Institute for Environment and Development

IPCC. 2018. Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Geneva: World Meteorological Organization.

Poore, J., Nemecek, T. 2018. Reducing food’s environmental impacts through producers and consumers. Science360(6392), pp.987-992.

UNEP. 2010. Assessing the Environmental Impacts of Consumption and Production: Priority Products and Materials, A Report of the Working Group on the Environmental Impacts of Products and Materials to the International Panel for Sustainable Resource Management. [no place]: [no publisher].

World Health Organisation. 2015. Q&A on the carcinogenicity of the consumption of red meat and processed meat. [Online]. [Accessed 23 July 2019]. Available from: https://www.who.int/features/qa/cancer-red-meat/en/