Carbon Footprint: Explained

The UN climate change report published last week (8th August 2019), called for a change in our diet, reducing our meat consumption and subsequently our carbon footprint. We’ve heard that term banded around a lot recently, “carbon footprint“, and although I understand the idea, what exactly is a carbon footprint and how are they calculating it?

The official definition of a carbon footprint is the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organisation, or community. It is a little more complicated than this though; other factors are included, not just carbon dioxide. That’s just a nice way of summarising it. To calculate our carbon footprint left by travelling or from the power we use is relatively easy. Travel accounts for 8% of the world’s global carbon emissions, and is growing. For your car, you can do this when you next fill it; make note of the litres added and the mileage before you leave the petrol station. When you then need to refill the car (from empty), make another note of the mileage. You can work out your car’s fuel economy/consumption by dividing the total mileage covered, by the litres of fuel used. Simple.

The same is done (roughly) for all transport we use, and hence, air travel is the worst as it covers the most distance and uses a lot of fuel. As part of the Paris Agreement, the UK aims to reduces its greenhouse gas emissions drastically. One way of doing this is to reduce non-renewable energy use, and we are getting there. How can you calculate your footprint from your energy though? Follow this LINK for how; you’ll need your energy bill.

The carbon footprint of your food is a bit more complicated. In recent months, media outlets have published various carbon footprint calculators for food. They’re based on findings from a paper published in Science by Poole and Nemececk (June 2018). They undertook a mammoth task, analysing data from ~38,000 farms across 119 countries, which produced 40 different types of food, be it meat, grain, dairy, nuts etc. The team looked at 5 environmental impact factors: land use, freshwater withdrawal, green house gases (GHG) either produced or consumed in production, and finally acidifying or eutrophying emissions (i.e. water becomes acidic or too rich in minerals/nutrients to be of use). Their study identified the carbon footprint of many food types (although I can’t find their actual calculations…thanks guys), and ruled that buying local is not always better, but buying local when the produce is in season is. So before you rush to the local market, don’t expect that buying your tomatoes in December is better than those imported from Spain. British tomatoes in December will have taken a LOT of (probably non-renewable) energy to grow.

What if we switched to vegan diets? The UN report did not suggest that we all become vegan tomorrow, but instead that we make a concerted effort to reduce our meat intake, especially red meat. Lamb and beef are the largest contributors to the carbon footprint of your food; check HERE for the breakdown. However, if everyone became vegan tomorrow, there are still problems. Where would we get enough water from to grow all the crops? How would we create enough arable land to farm to meet the demand of 7.7 billion hungry vegans? It’s not as simple as switching a field that once held cows to now grow your crops. Although, a report in PNAS from researchers at Arizona State University found that if, in the US, they culled farmed animals and we got their grain instead, food would increase by 23%. However, they also found that people would be deficient in MANY nutrients, and end up being more of a burden on health services; although the research did not allow for people taking supplements.

One solution could be genetically modified (GM) food or lab-grown meat, but I’ll save that for another blog post. Another aspect of our carbon footprint comes from our clothes and other land use, but again, this a whole other topic to get my teeth into.

Yes, we need to reduce our meat consumption and go veggie a few days a week, buy non-farmed fish and food which is in season. Equally though, buy a bike, walk where you can, and fly less. It was found that getting food delivered instead of driving to the supermarket can reduce your footprint by 0.5%, whilst having a vegetarian day just once a week can reduce it by 4%! Our carbon footprint is an important way to track our impact on the World (even if they don’t outline the exact calculations for me to easily find). This calculator by the WWF (World Wildlife Fund for those wrestling fanatics out there) is great, although there are hundreds to choose from. I have an hours commute on the train each day so my footprint isn’t amazing, but still better than the UK average!