Should I Stop Eating Meat? Part I
My main conclusions, setting the scene and framing the problem
The following ramble is an attempt to get clear in my head an answer to the question:
“If I stop eating meat (vegetarian) and/or other animal-based products (vegan), does that prevent global warming without damaging my bod?”
On the face of it the question is fairly simple and a quick Google will return hundreds of articles that will tell you unequivocally in Buzzfeed style that it’s the single most beneficial thing ever you could ever ever do for ‘the environment’. But:
- having a load of spare time on my hands
- being a bit skeptical — particularly of overly-simplistic answers and emotive anecdotal stories
- having a load of spare time on my hands
I just decided it would be worth checking it all out for myself. I also have a real bee in my bonnet about articles being written that appear persuasive due to facts and statistics that, whilst correct, are used completely out of context or not portrayed alongside other statistics that paint the rest of the picture. This monstrosity from Bloomberg is a great example of displaying large numbers (in absolute terms) to shock and wow — when in reality all numbers on a global scale are mega.
Nothing is particularly new or cool or niche here and is all just based on leafing through articles, papers and books written by people with much more expertise than me who have done all the heavy lifting — it’s just an effort to get the information straight in my noggin’ in a way I can refer back to when I forget.
This will probably come across like it’s been written by a child, but that’s just the way my inner voice works. And this is all about me. To prevent me having to read all my waffle every time I forget what I’ve concluded, let’s dump out the conclusions at the start.
Yes, eating less meat individually and collectively is not just important but necessary
Agriculture may not be the biggest slice of the puzzle when it comes to bringing emissions to zero, but it is still important. In fact it’s more than important, it’s necessary and individual dietary change plays a part in this. A plant-based diet is almost always lower in emissions than one that includes animal products and reducing (especially heavy) meat consumption can have a significant impact on an individual’s footprint.
Purely in terms of CO2e, calling it the ‘single best thing’ depends on your starting point
Like all individualistic comparisons, they are…individual. The more meat you eat to begin with, the more you travel, the more you do anything else carbon intensive then the story will be different for you. Understanding how to trade these things off against each other is the whole point of this so more informed decisions can be made and focus energy on what matters the most individually.
Not all meat is created equally and this has substantial impact on its CO2e
Like everything else we do, there are ‘good’ and ‘bad’ ways to do things and agriculture is no exception. The vast differences in farming practice and opportunity cost of land means that there exists a lot of variation in the emission profile of food. When buying food understanding roughly where it comes from in that distribution (e.g. through labeling) is helpful when trying to make an informed decision about the footprint of what you eat.
Food miles don’t matter — maybe only as a proxy for lower carbon food (if you live in the UK)
What you eat matters a lot more than where your food comes from. Arguably increasing your food miles to eat grass-reared UK beef would be the single best thing you can do if you live in Brazil and chow down on some Brazilian beef reared on deforested land fed pellets grown on more deforested land. But there are some gotchas. It is completely possible to switch from a meat-eating diet to a higher carbon vegan diet if you end up eating a large quantity of airfreighted food. Fortunately almost no food is flown these days — but it is possible if you eat a ton of blueberries, asparagus etc.
Regenerative agriculture isn’t a ‘free steak’, but best farming practices can greatly reduce the footprint of your food
Much of the ‘debate’ around this topic consists of building a straw man argument for the other side then swotting it away e.g. comparing best practice plant farming to worst practice industrialised livestock farming. Reiterating the above, not all meat is created equally and there are substantial emission reductions to be made from moving from the environmentally ‘worst’ practices to the best. It doesn’t absolve the need for demand change i.e. diet change, but it can still have a big impact and if you choose to eat meat then you should choose to support these farming practices with your wallet.
Food waste is arguably more important and reducing it costs you nothing (it actually saves you)
Almost everything in the ‘reduce your carbon footprint’ sphere is phrased like a choice — you must forgo something whether that’s convenience, comfort, travel or something you like eating in return for environmental credzzz. Food waste falls outside this mentality and as a result should be focused on even more. It also, again depending on your starting point, is likely the one most beneficial thing you could do if you are anything close to the average person living in the developed world. And you don’t even need to get into a debate with anyone about it because there are no known proponents of food waste. Kinda great.
With that in mind, let’s get chuggin’ through the waffle.
‘Set the scene’
The choice of the words ‘global warming’ rather than ‘climate change’ is deliberate (although it’s a myth that it was rebranded) because in order to keep a chain of logic that I can keep up with let’s keep things concise and measurable. On that note, the following assumption is made:
“Let’s assume all I care about is the effect of dietary choice on global temperature and no cares are given for biodiversity loss, species extinction, animal cruelty etc.”
I swear it’s an assumption. But in general all of these things go hand in hand. When it comes to the charts and numbers below they almost all give the same picture whether our benchmark is global warming, land or water usage, eutrophication, habitat loss etc. It’s a little similar to the idea in economics of the Human Development Index (HDI) rather than GDP. HDI is a more rounded measure and tries to capture the idea that money isn’t everything, but it correlates with the much more easily measurable GDP in developing countries — so in the interest of simplicity people focus on that. We’ll do the same here.
In general, what causes global warming?
Earth has an atmosphere. Which is fortunate because we need it. It has gases in it and those gases capture some of the sun’s heat and keep us cruising at a cosy avg temperature of 14 Celsius. We can think of the atmosphere like a gas warehouse — some stuff goes in (emissions), some stuff comes out (sinks). When there is too much gas in the warehouse, the temperature increases. When more gases are being added every year than removed (once their respective warming potentials are accounted for) then the rate of temperature increase will increase. However when things are in balance, the rate of temperature change stays constant. The issue currently is 2-fold:
- there is too much gas in the warehouse (so temperatures increase)
- every year more and more gas is net going into the warehouse (so the rate of increase accelerates)
This NASA page provides ample evidence for the link between ‘greenhouse gas’ (GHG) emission and rising global temperatures or also this primer from Project Drawdown, but a quick Google will bring you up any number of other sources that have zero monetary benefit to promote the (causal) relationship. Which is important because biased opinions manipulating statistics suck. So the next question becomes:
If GHG cause global warming, how do we measure them?
Before we start looking at what activities emit GHG, we first need a way to measure them and compare them. There are many greenhouse gases, but let’s just focus on a few as these are the ones both relevant to agriculture and most prevalent:
- Carbon Dioxide (CO2)
- Methane (CH4)
- Nitrous Oxide (N2O)
Each of these has their own emitters and sinks/decay processes so we could keep track of them individually, and at some point it will be important to distinguish between them. But to keep things simple for now we can simplify to a single common denominator. This common denominator is bandied about everywhere and is called CO2e — CO2 equivalent — and normalises the Global Warming Potential (GWP) of these gases by using their 100 year GWP to the same as CO2. GWP is based on the combo of:
- how much heat they trap over a given time period
- how long they stick around in the atmosphere for to trap heat
and is the measure agreed in the 2013 IPCC report for measuring and target setting. As an example, methane only sticks around for around 10–12 years but traps a lot more heat than CO2 — so on a 20 year horizon it has a GWP of around 85x, but on a 100 year horizon (standard) is more like 28x. And yes, GWP has its problems as highlighted here by one of the original authors of GWP, but let’s stick with it for now and later check if a changing of comparison framework affects our conclusions.
So the next question becomes:
How does agriculture fit into the picture? Surely it seems quite ‘natural’ vs blazing those fossil fuels?
Right. So now we know what causes global warming and how we can measure it, let’s now look at what it is that we’re up to that is emitting more GHG than the earth can sink and warming the planet in the process. This is the bit where we start to get into numbers and, unlike how I thought science works in school, the numbers vary because things are uncertain (measurement error, classification uncertainty, ‘bad’ science etc). Best to look at a variety of sources and then if the numbers differ wildly try to understand sources of differences. First up, this pie chart (original article here) put together by Hannah Ritchie (HR) at Our World In Data (OWID) using data from Climate Watch (2016), illustrating how the emissions from our various activities break down:
So it seems like agriculture does have a part to play. According to this pie chart it accounts for about 1/5 of all GHG emissions. So it’s on the map. But, as perhaps is more intuitive, blazing those fossil fuels for energy makes up the biggest component at around 3/4. Now we can also have a look at this graphic put together by Project Drawdown to see how they have broken it down by sector:
So a fairly consistent picture thus far when we look at total emissions broken down by what we get up to. Agriculture seems to be making up around 1/5–1/4 but with the majority of other GHG emissions resulting from ‘energy use’ distributed across the sectors that use energy (industry, transport, electricity generation).
So if it’s only 25% of the problem, why focus on it?
Good question. Also it shouldn’t really come as a surprise that making food is a big slice of our GHG pie. In general we like to:
- eat things
- make things
- go places
so it shouldn’t be all that OMGWOW!!!. Plus, usually the best approach for a problem is to start with the big components and ‘quick wins’ and then worry about the smaller pieces of the pie as you go (if you even have to). So why so much noise about what we eat when it appears to be one of the smaller slices of the pie? To be facetious, is this all just a ruse by the ‘fossil fuel industry’ to detract us from the real problem — extracting and burning fossil fuels?
The mainstream focus on agriculture, and particularly on animal agriculture, is the legacy of the UN’s Food and Agriculture Organisation (FAO) report in 2006 called ‘Livestock’s Long Shadow’. It stated that livestock accounts for 18% of GHG emissions and made the statement that this is ‘greater than the combined exhausts from all transport’. Whilst this comparison is a bit shoddy and was later corrected here by the FAO (under pressure from this) it was enough to grab headlines and put agriculture on the map as potentially a bigger problem than the more readily available image of cars spewing GHG out into the atmosphere. It’s worth noting that the FAO revised their figure for livestock in a 2013 publication to 14.5% (putting an overall agri estimate in line with ~20%), but the question still remains. Why focus on it?
We can answer this by looking at the question in reverse — what happens if we don’t focus on it?
If all we care about is global warming, and as established GHG cause global warming, then we can think of the problem like this — how much more GHG can we emit and keep global warming below a certain temperature? Phrased like this, once we set a temperature change we’d like to keep below, we kind of have a remaining GHG budget to spend. As per, we don’t need to figure out the variables in the equation here ourselves (temperature change & remaining GHG emissions) but can rely on the winning combo of:
- clever scientists
- other clever people making it accessible with visuals and highlights — almost always Hannah Ritchie at Our World In Data
to generate it for us. The below chart is from here and based on this paper and compares the following things:
- the top blue bar: an estimate of cumulative GHG emissions from agriculture between 2020–2100 if we continue ‘as we are now’. This assumes human population growth at trend, dietary trends continue in their shift toward ‘western diets’, productivity gains in agriculture continue at the current trend (they assume yields increase by 30% by 2050, 68% by 2100 — so the authors are no Malthusians)
- the orange and red bars: estimates of the remaining ‘GHG budget’ to contain global warming below certain temperature changes (1.5 and 2 degrees) with varying modelled degrees of certainty (67% and 50% chance)
So what does this tell us? It tells us that despite food being a smaller part of the puzzle, it’s a part that needs focusing on. Specifically we can tease out a few main points:
- with no major changes to agricultural output (either through technological changes on the supply side or dietary changes on the demand side), we will blitz through our 1.5 degree goal — can be seen by the blue bar being much larger than both orange bars
- again with no major changes, to have a 67% chance of staying below 2 degree change (top red bar) we would have to stop emitting GHG from all other human activities today. To repeat, even if we stopped burning fossil fuels tomorrow — an impossibility — we would still go well beyond our 1.5°C target, and nearly miss our 2°C one.
In no way is this dismissing the need to focus on clean energy generation, more that agriculture is not just worth focusing on but must be focused on globally if the targets set for maximum warming are intended to be met.
Quick Recap
Alrighty — so what have we established so far?
- GHG emissions cause global warming (if you’re not convinced of this first part then the rest probably isn’t for you)
- agriculture accounts for roughly 20–25% of annual GHG emissions (potentially more)
- despite being a smaller component of the pie chart, it needs to be focused on to prevent the worst projected outcome of global warming — a 2 degree temperature change
All clear? Great. Onward to Part II.
