2015 climate change march in London. Photo source: photo: Alisdare Hickson

We are facing a climate emergency.

We all know the drill by now, our planet is suffering and humans are largely to blame. Increasingly studies are being churned out highlighting how our feeding habits are hurting the Earth. With an ever-increasing population and a growing global demand for red meat are we eating ourselves and our Earth into an early grave?

Climate change protest. Photo source: Emma Bjornsrud

It feels like climate disasters are occurring every other day, with people flocking to the streets in protest of governmental inaction on climate change. More and more we are being made to feel like we as individuals are at fault. But how far are our individual actions really responsible climate change? How much difference can a single person make? What exactly do we mean when we say sustainable diet? And what, if anything, should we be changing to help our Earth?

How do our diets effect the environment?

Different foods have different environmental impacts, requiring different amounts of resources to take them from their point of origin to your plate. They require water and land, nutrients and energy all of which contribute to our growing climate problems. One of the biggest problems with our food habits is the associated greenhouse gas emissions (GHGE), which are damaging the natural world. Our current food system is destroying the environment and protein rich western diets are the biggest culprit.

Customer looking at beef selection. Photo credit: Bloomberg

It is estimated that by 2050 the global population will be 9.8 billion. When looking only at emissions from animal agriculture it is thought that by 2050 there will be an increase of 80% on current levels. In fact some estimates predict that we will exceed our emissions limit by 2030 through agriculture alone. With the ever present warnings of the need to limit global temperature increase to 2 ° C, can we really afford to keep eating the way we are?

It’s not just GHGE we need to be mindful of either, animal agriculture is also responsible for 78% of global eutrophication (when a body of water becomes overly rich in nutrients) and 32% of global terrestrial acidification (increased acidity of soils). Eutrophication can be disastrous for the natural environment as enriched waters can lead to the growth of algae which prevent oxygen from entering the waters and stop life from flourishing, creating a dead zone. One such example of a dead zone is the gulf dead zone in the Gulf of Mexico. So what can be done?

Figure 1: Dissolved oxygen levels in the gulf dead zone, red shows the areas with the lowest levels, green the highest. Source NASA NOAA [Available at: https://commons.wikimedia.org/wiki/File:Dead_Zone_NASA_NOAA.jpg%5D

What is a sustainable diet?

To talk about sustainable diets we first need to understand what they are. Whilst exact definitions are still debated as many complex issues need to be taken into account, the simple understanding of sustainable diets is one that allows the current population to meet their nutritional needs without jeopardising the ability of future generations to also do so.

So which foods are better?

Take for example a potato, this potato will need space to grow, water and nutrients to feed it, energy to harvest it and to transport it to our plates. Now consider a chicken. We first need to hatch an egg, then feed the chick that hatches, keep it healthy and warm, fatten it up, transfer it to slaughter, process it and then transport it to your plate. Clearly here it will require more energy to produce and transport the chicken than the potato. In fact, if you were to eat potato once a day for a year it would contribute 16kg to your carbon footprint however, chicken once a day for a year would contribute 497kg, showing potato to be considered as more sustainable.

When it comes to unsustainable diets the largest offenders are meat and dairy, the global production of which is estimated to contribute 14.5% of total global climate changing gases, more than the combined exhaust from all transport. This link between meat, dairy and climate changing gases is one of the major factors leading to increasing pressures for individuals to give them up and switch to a more sustainable diet. One of which is veganism.


Figure 2: The percentage of total global emissions produced by animal agriculture. Data source: https://ccafs.cgiar.org/bigfacts/#theme=food-emissions&subtheme=direct-agriculture. Adapted from Gerber et al. 2013. Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities. Rome: Food and Agriculture Organization of the United Nations.

What is veganism?

Initially veganism was defined as a diet that prohibits the consumption or use of all animal products including any meats, eggs, dairy, honey, wool, etc. However, it has since developed into a fully-fledged philosophy focused on ending the exploitation of animals by man, and decreasing our negative impact on the natural world. Whilst some debate a difference between vegan and plant-based, for the purpose of this article the two terms are considered the same. Plant-based diets have existed from as early as the times of the roman gladiators known as the “barley men”. However, it is only recently that veganism has begun to rapidly increase in popularity. During the past decade, the number of recorded vegans has increased by 160 percent.

How much difference can a vegan diet make?

Okay so eating meat is damaging to the planet, but how much difference can one person make? Due to variance in individual plant-based diets it is impossible to say exactly how much difference each individual can make, but there are some pretty good estimates. When considering water, it is thought that adopting a plant-based diet could save more than 150,000 gallons annually. A year of veganism has been said to save 10,950 square foot of forest, 7,300 pounds of carbon dioxide and 14,600 pounds of grain. If we start to scale this up, say you were to live 80 years as a vegan you would save approximately 876,000 square foot of forest. That’s just over 15 football pitches of forest saved by your lifestyle choice alone.

Many calculators exist now to help illustrate the impact you or your family’s diet can have on the planet. Some let you see the carbon foot print of each ingredient in a recipe, others allow you to see the impact of swapping one red meat meal for one plant-based meal, or compare different foods and drinks carbon footprint. The overwhelming impression this then gives is that veganism is better for the planet, and we should all adopt a plant based diet, right? But is this all we have to consider?

Protesters campaigning for vegan diets and against animal agriculture. Photo source: Nathaniel Wallis.

Veganism alone won’t save the planet.

Whilst veganism begins to offer a path to a more sustainable diet, it is not the only thing to consider. We have to think about where our food comes from. For example recent studies on asparagus have shown that its total GHGE are 6 times higher than the next highest vegetable. This is because of the distance it has to travel and how quickly it needs to do so. Here, in the UK, our asparagus is largely supplied by Peru, and it has to reach us quickly before it decays. That’s a lot of distance to cover in not much time, meaning the only way to transport it is by air. It is this that makes asparaguses GHGE so high.

Air freighting when compared to shipping by sea has been found to use 50 times more energy. Therefore, foods that can reach us by sea will be better for our planet than those that must be flown to us, such as many soft fruits and vegetables. This means that a meal containing meat produced at a local farm may have a lower environmental impact than a bowl of veggies that have travelled from the other side of the world. So not only do we need to consider the environmental impact of the production of our food, but also the distance travelled: its locality.

We also need to consider the seasonality of our foods, when a given produce is at its peak in either flavour or harvest. Are we buying foods that naturally grow their best at that point in time, or are we consuming what we want to taking no notice of whether our strawberries were forcibly grown at a time that means more energy has to be used. In the UK, a strawberry grown in august will have a lower carbon footprint than a strawberry grown in December. Whilst technology improvements can aid the reduction of emissions when growing foods outside of their season, in season will always be more efficient than out of season.

Fresh British seasonal foods. Free source

So what’s the answer?

While you adopting a vegan diet may not right all the worlds’ environmental wrongs, it is a step in the right direction. Some claim a plant based diet is the single best way an individual can reduce their environmental impact. However, it is clear that this is not the only thing to consider. The issue is a complex one and not something that is easily solved. But if we all made a conscious effort to eat a more plant-based diet, one as locally and as seasonally supplied as possible then a real measurable change could be observed. It feels as though we are running out of time to do something for our planet, and while I cannot promise you giving up your beef burgers will save the Earth, I can tell you it will make some difference and surely that is what is most important.