“Foodprint” – The Environmental Impact of Human Diet

Food has been increasingly feeding climate change – not just our bodies: it is currently the main contributor to the Ecological Footprint in many parts of the world. The detrimental effects of our dietary patterns on Planet Earth’s health have even surpassed those of fossil fuels in the transportation sector for a significant proportion of countries. How are our plates flying higher than planes in the pollution landscape?

The damaging effects of human activity on the environment are often linked to fossil fuels, particularly for transportation purposes. However, food has become the leading cause of excessive ecological Footprint in many countries, namely in Portugal.

The concept of the Ecological Footprint refers to the amount of land and water – farmland, forests and fishing areas – measured in global hectares, required to support current generations, taking into account all the resources consumed by a given population. We can measure the impact of human activities in parameters such as greenhouse gas (GHG) emissions, biodiversity loss, water, land and energy consumption, among others. Animal agriculture is one of the main responsible industries for these nocuous effects, putting a heavy strain on many of the Earth’s finite natural riches. 

The animal products supply chain accounts for a higher depletion of raw materials and higher GHG emissions when compared to plant-based foods. Chocolate, meat (especially red meat) and dairy are amongst the foods requiring the biggest amount of water for its production and  generating more GHG emissions.

If global consumption of meat and dairy continues to grow at the current pace, the agriculture sector could consume about 70% of the allowable budget for all GHG emissions by mid-century. A study at Oxford University showed that excluding meat from our diet can reduce them in half. The group compared the CO2 emissions of 55 000 consumers, including vegans, vegetarians, pescatarians and those who don’t make any restrictions. The results revealed that meat consumers produce 7,3 kg of CO2 per day and those who only eat fish produce around 3,9 kg of CO2. The most significant reduction happened with those who don’t consume any meat at all: 3,8 kg for vegetarians and 2,9 kg for vegans.

Tackling Climate Change Through Livestock, a 2013 report by the United Nations Food and Agriculture Organization (FAO), estimates about 14,5% of global GHG emissions are attributed to the livestock sector annually, which is broadly equivalent to the amount released by all fuel burned by all the world’s transport vehicles. Animal agriculture accounts for 5% of global anthropogenic CO2, 44% of anthropogenic methane, 44% of all anthropogenic nitrous oxide and 75-80% of total agriculture emissions. The release of methane, the primary driver of climate change-related to livestock, is caused by enteric fermentation, animal manure, loss of carbon in the soil (due to land-use change and degradation), manufacturing of nitrogenous fertilizers for feed production and clearing of trees for agricultural expansion.

To accommodate the 70 billion animals raised annually for human consumption, a third of the planet’s ice-free land surface, as well as nearly 16% of global freshwater, is devoted to growing livestock. If a person would change into a plant-based diet, he or she could save around 615 000 L of water per year, reducing the individual footprint in half. 

Furthermore, a third of worldwide grain production is used to feed livestock. By 2050, the consumption of meat and dairy products is expected to rise by 76% and 64% respectively, which will increase the resource burden from the industry. The following tangible example shows the optimization issue at hands: with the same amount of raw materials, instead of producing 115Kg of beef, we could produce 20 000 kg of tomatoes, 24 000 Kg of potatoes and 13 000 kg of carrots.

The livestock sector is the largest contributor to global water pollution. Globally it produces 7 to 9 times more sewage than humans, most of which is left untreated. Irresponsible manure management from high-volume facilities risks aerosolizing fecal matter that may reach nearby homes and cause respiratory problems. Livestock waste can pass through the soil to groundwater, which may then contaminate nearby streams and rivers with nitrates and pathogens. It also discharges pesticides, antibiotics and heavy metals into water systems. This poses a public health threat on various fronts: viral diseases may spread from sick livestock to humans and increased use of antibiotics leads to antibiotic resistance.  

Sparing land from conversion to agriculture is essential in protecting biodiversity. The livestock sector is one of the leading drivers of global deforestation and is linked to 75% of historic deforestation in the Brazilian Amazon rainforest. This happens not only to free the area for animal farming but, more importantly, to produce the nourishment of those animals in extensive crops (ex.: soybean crops). Monoculture plantations play a key role as well. Nearly a third of biodiversity loss to date has been linked to animal agriculture.

It is estimated that by 2050 the world’s population will reach 9,7 billion, 32% higher than today. As the population increases, so does the demand for food. Moreover, the tendency today is for populations to become more urbanized with higher incomes, which shifts typical dietary patterns towards patterns based on animal products. For instance, in the Mediterranean region, the Ecological Footprint is mainly attributed to food, even ahead of the transportation sector. Portugal is the country in the area with the highest per capita food Footprint. Such a fact arises from a  protein-intensive diet and a high-calorie intake with proportionally more products from the fish sector, especially high trophic level fishes like codfish or tuna, thus placing a high demand on the planet’s marine primary production.

The consequences of reckless use of our planet’s resources are palpable: land erosion, desertification, shortages of water, polluted oceans and GHGs emissions worsening by the second. 

The ideal diet is still under discussion but one thing is consensual among the reviewed studies: decreasing animal products consumption would have an undeniable positive effect on optimization of resources, reduction in pollution levels and maintenance of biodiversity.


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