Photo by Jan Huber on Unsplash

Should I Stop Eating Meat? Part V

Finally digging into what generates CO2e in the agriculture black box

Part of a series. Part IV here.

Farmville 2.0

I was never very good at it but I do remember firing up the computer pre school a few times to check on my crops. It’s time to re-create (theoretically) Farmville and try to tease out a bit of understanding of where these GHG come from. Without this it’s going to be very hard to ballpark CO2e of different food and that’s the aim here. In the absence of concise labels (a la Oatly – which shouldn’t be cancelled btw) on all of our food giving the specific CO2e of that specific piece of meat or veg, we have no real idea how to make informed decisions when it comes to which part of the emissions distribution a given piece of food is from. Is it from the 10th percentile or closer to the 90th percentile?

The aim is to build some kind of ‘heuristics’ — quick ways to help identify CO2e barrels or on the other hand more CO2e-lite products. Let’s build our farm and hopefully in the process tease out how CO2e numbers can vary so much within a given foodstuff. At this point it is definitely worth mentioning I have less practical farming experience than a potato. I do know that a peanut is not a nut though so that counts for something.

Where? (‘Land Use Change’)

First things first, we need some land. And if we’re using it to grow crops then preferably flat land with good nutrient-rich soil. And in the absence of any other incentivisation that will be the optimisation process: find the land that could produce us the highest £ yield of crops. If that land is a forest then so be it. Let’s buy it, burn it, till it and print that £££.

But when it comes to GHG, this poses some problems. Not all land is equal because some land can ‘sink’ more GHG than other land. If we cast back to the beginning when we looked at GHG in general we talked about the fact that the atmosphere is like a greenhouse gas warehouse but that there are natural processes that can sink GHG. Some land has more ability to sink GHG than others. Specifically the ability to sink carbon — or as it’s distractingly called ‘sequester’ carbon.

Carbon is sequestered through photosynthesis and that is done mostly by green stuff. Plants, trees, grass. The more green something is and the longer it’s green for the more it should be able to sequester carbon through more photosynthesis. So if a piece of land has the potential to foster lots of green life for most of the year then that piece of land has a higher (environmental) opportunity cost when it comes to choosing it for our wicked cool farm.

This is a major reason why how much land a certain food type requires (either to live on or to grow food for it on) has a major impact on its CO2e footprint (the green portion of the supply chain bars above). Because if that land could be used to photosynthesise (or photosynthesise more), then there is a CO2e opportunity cost of using it as farmland. In categorising emissions this (called Land Use Change (LUC)) is often reported in a separate section but this usually misses the point. Not factoring this in is the same thing as finding a vacant plot of land in central London and valuing it at £0 because there’s nothing there. It misses the fact there is the opportunity for it to be valuable — just like some non-photosynthesising land could have the opportunity to be converted to photosynthesising land.

But insisting that we plant trees on farmland is not the answer. As will start to be hammered home, generalised solutions for a diverse range of situations don’t work in finance or tech, so why would they work in agriculture? Insisting that you plant a forest on a grassy hill somewhere in the northern hemisphere (and offer you for £3 the chance to feel good about your return flight to Lisbon as a result) is maybe not the best idea if those trees will only be green for 5 months a year; instead of the existing green grass that photosynthesises 365 days a year. So just like not all meat being equal, not all land is equal. In fact, it’s the other way round. Because meat is land-intensive and not all land possesses the same carbon sequestering potential, not all meat is equal as a result of land not being equal when viewed through the eyes of carbon sequestration.

Plant Those Crops

We’ve got our land. Let’s forget about whether it’s deforested rainforest or grassy fields for now. It’s now time to get planting our crops. Images of tilling fields and fields of wheat come to mind (whether or not Theresa May is gallivanting through them). But tearing up the soil once again adds to our GHG emissions. Soil might not be green but soil can capture lots of carbon when you have photosynthesising stuff on top of it. NHN points out in her book ‘Defending Beef’, borrowing from this source, that “more carbon resides in soil than in the atmosphere and all plant life combined”. She also explains how the process of soil carbon sequestration is thought to work and I think it’s worth repeating my own version.

“Plants photosynthesise. As a result they convert CO2 in the air around them into carbon and oxygen. Which is great for us, but strangely they aren’t just selfless beings doing it for the greater good. They need it to grow because they can use it as a bargaining chip (read: trading!!!) with organisms that live in the soil. Around the plant’s roots exists “mycorrhizal fungi” which are like big long thread like fungi that reach far off into the soil and are like a big web that facilitates ‘transactions’ between the plant and the enzyme/protein-producing organisms in the soil. The plant has carbon and the organisms need it. Time to trade. Bit of carbon for you, bit of phosphorous for me. Bit of carbon for you guys, I’ll have some nitrogen. All the while the plant feeds the carbon down into the soil getting some nutrients back and growing.”

So potentially soil can act like a big store of carbon and how we choose to plant our crops can affect if we manage to keep the carbon there (tilling or no-tilling). We’ll review this idea shortly.

Feed those crops

They’re planted. We’ve got those seedlings in the ground. But we want them to grow up to be big strong heavy crops that we can sell for lots of £££. That’s why we’re here. And for that those crops need nutrients. And yes, as described above they can get those nutrients from the soil but:

• that assumes the soil has lots of nutrients already to give (rather than being used up in last year’s incarnation of Farmville 2.0)
• that assumes that is sufficient for the crops to achieve maximum yield

And maximum yield is important. Because the more we can grow per field then the fewer fields we need and the fewer fields we need then (potentially) this un-required land could be used for some degree of photosynthesising. In fact, higher yields are more important than that. Rising agriculture yields in the 20th century have potentially enabled the lives of 1 in 2 of us by enabling us to be fed. What has largely driven those gains?

Fertiliser. Which is one reason why Bill Gates is such a fan of the stuff that he even travels to factories and gets thumbs-up pictures taken with it. Pretty cool. The Haber-Bosch process to synthetically create nitrogen fertiliser is one of the biggest inventions in our history (9 min BBC listen here). It’s enabled us to make huge gains in how much food we can grow and how efficiently.

But why does fertiliser seem to get a bad rep? Less because of what it is, more because of how it is used. It’s true that it takes a lot of energy to create through the pressure and heat required in its manufacture, but this isn’t the main issue. When fertiliser is actually applied 1–5% of the nitrogen in it gets released as nitrous oxide through reactions happening in the soil (I found it incredibly hard to find info on what ‘reactions happening in the soil’ actually means but this was as close as I could get). And this is bad — because N2O has a GWP of 265x when compared to CO2.

But it turns out that over-application of fertiliser is a big cause of this and careful application can reduce this significantly. To reiterate, fertiliser: good. Too much fertiliser: bad. Unsurprisingly HR has put together very insightful graphics here on which countries are using ‘excess fertiliser’. But the point remains, a byproduct of us feeding our crops is a highly warming GHG and that non animal agriculture does produce GHG.

Collect that harvest

And finally we need to collect it and get it out the farm gate in return for that much sought after £££. Throughout the whole process we will needed to have used machinery to get it all done emitting CO2 as they are powered by fossil fuels unless we only want to run a back garden sized operation. We might also burn some residues of stuff that we can’t sell releasing the CO2 in that matter into the atmosphere.

So to sum up, we’ve done our whistle stop harvest and found out:

• land has a potentially large CO2 cost of using it as farmland
• tilling soil for our crops might release even more CO2 into the atmosphere
• nitrogen fertiliser, particularly when over-applied, releases N2O into the atmosphere
• the whole thing requires CO2 powered machinery to enable

What about animals?

Oh yeah. The elephant in the room (there’s definitely a dad joke in there somewhere). With animals we can think about them as extensions of what we’ve looked at above, particularly when we pretend that we don’t care at all about them and treat them purely as a commodity.

First things first we need somewhere to keep them. Preferably using as little space as possible because land is expensive (in both economic and environmental terms). Unless they are cows/sheep in which case maybe we can find some cheap grassy hills for them to graze on in which case we don’t need to feed them as much because they can just eat the (free) grass. So the same problem with crops applies to animals — we need land for them to be on and this land has a potential carbon opportunity cost.

Next we need to feed them. What are our options?

• feed them stuff humans can eat
• feed them stuff humans can’t eat
• feed them a mixture

Fortunately capitalism comes to the rescue here and we don’t generally feed them human-edible food — because humans pay more for food than cows. This paper estimates that in fact we only feed cows 14% of human edible food. It is true that in some cases we could use that land to grow human-edible food but let’s ignore that for now. The real issue is that we need to feed them a lot. And when it comes to feeding them non-grass, then we’re straight back into the above issues that we have for growing crops. We need potentially carbon-sequestering land, nitrogen fertiliser etc. For visualising this, MBL again comes to the rescue with an amazing graph from one of his other books There is No Planet B. But he’s also got it sitting on his Twitter account from the paper he published here so we can use it.

Image by Mike Berners-Lee from here

This shows a breakdown of how calories flow through our food system globally going from left to right. We’ve talked about how protein is potentially a better benchmark when it comes to animal-based products but the graphs are basically the same — if you don’t believe me you can see the full suite of flow charts here. The key part is in the middle of the chart titled ‘animal losses’. What is this showing?

• even though we (mostly) do the normal thing and try to feed our animals as much non-human edible food as possible, we still feed them on average 1,738 kcal of non-pasture each day
• through being alive (walking, burping etc) animals then ‘waste’ not just 2/3 of this energy but also all of the 3,812 kcal of the grass and pasture we feed them
• as a result, they then only contribute 594 kcal per day to our globally averaged diet

So yes, we do try to feed them non-human food but even still the quantity of food that animals require means that we feed them almost a full day’s worth of calories. And those calories need grown on land and that land has a cost.

So is the on average higher CO2e footprint of animals just down to this?

Unfortunately not. We then have 2 further (main) issues — but let’s keep them short as they’re more well known.

As a byproduct of doing that magic ‘grass-to-meat’ thing, cows and sheep produce methane. Unlike has been popularised it actually mostly comes out their mouths (around 90%) not their other ends, but nevertheless this is a bit problematic. Because methane has a GWP of 28x. And whilst there are ways to reduce this through improving feed quality, feed additives and a whole myriad of other things being worked on, currently that’s a lot of GHG.

Poo. Lots of poo. Animal manure isn’t necessarily a bad thing. In fact, it can be a very good thing if used as natural fertiliser instead of synthetic fertiliser to help in the production of crops — there is some evidence that synthetic fertiliser oxidises more than manure causing more N2O. But in the current state of industrialised agriculture, primarily confined animals such as poultry, pigs and dairy facilities the creations of ‘manure lagoons’ emit methane.

Is the problem just industrial livestock management? What about ‘regenerative agriculture’?

This feels like an appropriate point to take a detour into the quite trendy notion of ‘regenerative agriculture’ (and if you fancy a proper good look into the arguments for it then go and read NHN’s book). The (heavily simplified) idea here is the following:

• soils can capture lots of carbon (explained above)
• grass is a a great way of doing this given it’s green all the time
• ‘managed grazing’ of animals is a good way of keeping that grass healthy through tractor-less fertiliser (manure) being spread around (and some other things)
• humans can’t eat grass but ruminant animals (cows, sheep) can
• not only that but they are kind of magic and can transform this ‘pure cellulose’ into nutrient rich food (beef, lamb, cow’s milk) that we can eat
• so it’s the best of both worlds — good nutrient dense grub for us, lots of carbon in the soil — which as mentioned contains loads of the stuff

And there are lots of points here that have merit. As this paper points out cows can actually perform a bit of magic and add protein to the food chain despite overall consuming huge quantities of food. Soil carbon sequestration also has large potential to drawdown some CO2 from the atmosphere with Project Drawdown ranking it around 16th in their table of solutions — more on them later. But there are some caveats:

• you need to not churn up the soil forever once you start otherwise it all comes back out
• there’s evidence that the soils get ‘loaded’ after a while so you’re not sequestering much more carbon
• it’s 16th in Project Drawdown’s list, not number 1. I’ll leave it to the imagination what they rank higher
• the science is young and uncertain. In particular there are studies showing that potentially the higher carbon density of the soil is the result of carbon being drawn up from lower soil rather than down from the atmosphere. There’s good stuff on this here, here and here.
• as illustrated above, animals waste a lot of energy in the food chain. If we were to convert croplands into grass for animals to feed on (with the grass potentially sequestering carbon into the soil offsetting the methane produced by the animals) then we’d need loads of land. Because in order to still produce the same amount of calories that we were producing from the crops we used to grow on that land, we’d need lots of animals and therefore lots of grass for them to eat.

TLDR: the science is uncertain, it might work in a localised way, but it doesn’t scale.

So what have we learned?

It might feel like this has been a bit long windy and ramble-y (I think it’s because it is) but the point has been to try and tease out some reasons why even when we look at a piece of beef the numbers for the CO2e profile can be so varied. To make some conclusions about what we’ve looked at:

• where we grow food that we eat matters. Rainforests and anything else with high photosynthesising potential has a very high associated CO2e cost
• where we grow food that we feed to animals matters. We might house them in grassy rainy England but if we feed them food we grew on deforested rainforest then we’re not helping much
• energy cannot be created or destroyed. Unless you feed it to animals in which case then we have a bit of a leak in that they use this energy to be alive pre-slaughter (how dare they???)
• cows and sheep produce a byproduct of methane which is quite unhelpful as they produce lots of it and it has a high GWP
• agriculture is complicated, location and situation specific and that manifests itself in wide CO2e distribution even within food groups

Does that mean we can’t answer the original question?

No, that’s now next on the agenda. Just that it’s all a bit complicated and looking for a simple catch-all soundbite solution will leave you floundering. As H. L. Mencken puts it:

“For every complex problem there is an answer that is clear, simple, and wrong.”

But now let’s attempt to wrap things up.

Should I Stop Eating Meat? Part VI