Should we switch to a vegan diet to save the planet and feed the world? What is the ultimate ‘sustainable food?’
Imagine a wonder crop that has deep roots that tap into hard to reach nutrients underground, it’s drought resistant – when it rains the root system helps the water stay in the soil instead of running off. This crop can resist the highest winds or the wettest spells, it grows well all year round and on any type of soil. This crop could provide food security even in the most erratic rainfall caused by climate change.
Our wonder crop helps to oxidise methane and takes carbon from the atmosphere and locks it out of harm’s way, it builds its own fertility so needs no artificial fertilisers – one of the most carbon-heavy and energy intensive inputs in modern agriculture. This crop requires minimal management; no machines, no pesticides, no irrigation, it does not need to be planted every year, and it can grow anywhere – even on mountainsides, arid plains, or wetlands – the places where no other food can grow.
Sounds great, but there is one HUGE problem. We can’t eat it! It’s called GRASS.
But as evolving humans we got around this issue – we ate the animals that ate the grass (along with seasonally available plants).
Ruminants – like buffalo, elk, cows, and sheep – have clever digestive systems that can turn this wonder crop into meat and milk. The meat doesn’t need storage, can be moved from field to field, it doesn’t often spoil or rot, and we can harvest when we need it – regardless of the weather or time of year. Some of these food animals even produce nutritious milk without any loss of life. As a pleasant ‘by-product’ it also tastes AMAZING and you can get nearly all the nutrients you need to thrive from the different parts of an animal.
The Food and Agriculture Organization of the United Nations says, ‘animals can offer several advantages over crops in developing parts of the world’ and goes on to note;
• Meat and milk can be produced year-round, being less seasonal than cereals, fruit, and vegetables.
• Animals, particularly small ones, can be slaughtered as the need arises, for food or income.
• Both milk and meat can be preserved – milk as clarified butter, curd, or cheese; meat by drying, curing, smoking, and salting.
It’s easy to cherry pick the most productive crop in terms of calories or protein levels and use this as a direct comparison to meat to offer an alternative more ‘efficient’ food source for a growing population. Humans, however, cannot thrive on one or two crops; we need a varied, culturally and geographically appropriate, environmentally sustainable diet that delivers all the nutrients humans need to be healthy.
Animal foods are nutrient dense and offer a wide range of vitamins and minerals in a highly bioavailable form unlike many plants that have anti-nutrients that inhibit absorption in our gut.
When deciding on the most sustainable diet, it’s important to go beyond comparing individual crops and assess what range of foods a person would have to include in their diet to replace the nutrients found in meat and dairy.
In this study when different diet scenarios were created that achieved national nutritional recommendations, the vegan diets fared poorly in overall greenhouse gas emissions comparison the those that included the nutrient dense animal foods. 1
BUT’ – I hear you say… “Cows burp and fart too much which is causing climate change and we can’t feed 9 billion people from this system there is simply not enough land!”.
We’re going to tackle these two issues head on.
Land use and feed to food conversion.
There’s a flawed argument that suggests we that we haven’t got enough land for meat to be a part of a sustainable diet of the future. The truth is, we can’t even come close to feeding the world in 2050 without including animals in a global diet.
70% of all agricultural land is currently used to rear livestock, but, the point that is often conveniently overlooked is that much of this land is unsuitable for arable cultivation which is why it is used for livestock production – it’s just too rough, dry or steep to be used for commercial vegetable or cereal production.
Livestock use 2 billion ha of grasslands, of which about 700 million could potentially be used as cropland, so there’s limited scope for switching from meat to plants entirely.
If we remove livestock from this system, we would lose valuable recycled fertility too. Approximately half of the fertility we add to crops comes from manure. To remove this free and biologically appropriate fertility source would mean having to double the manufacture of synthetic fertilisers – one of the most energy intensive and environmentally damaging inputs in agriculture. 2
We can’t make up the gap with so called ‘sustainable intensification’ either as the increases in crop yields are falling well short of the increases in human population.3
There is good reason to assume that a warming and more erratic climate will lead to a reduction in crop yield rather than an increase.4
Delaying action in the hope we’ll receive technological salvation from an entirely biological problem seems like a really bad idea.
We also need to question the assumption that we’re always in direct competition with livestock for our food.
It’s not that simple.
We actually need efficient livestock systems to ‘soak up’ the vast quantities of by products and waste crops that inevitably comes from intensive plant production. There is only a small proportion of the global crop harvest that is suitable to be processed into cornflakes and a tofu. 86% of the global livestock feed intake in dry matter consists of feed materials that are not currently edible for humans, this would be ‘waste’ were it not fed to livestock.
We often hear huge figures thrown around in relation to the feed to food ratios of different livestock production systems. Some will say it takes 15kg of grain to get 1kg of meat – this argument is often used to justify an increase in sourcing meat from monogastric species of livestock such as pigs and chickens.
But when you analyse the feed these livestock eat and only count the grains that could feed human instead a different picture emerges. Producing 1 kg of boneless meat requires an average of 2.8 kg human-edible feed in ruminant systems and 3.2 kg in monogastric systems. If you compared the nutrient density of the output animal foods to the cereals fed to the livestock there is no question which contributes more in terms of nutrition security.5
It is vital we address the drivers of deforestation and soil degradation which are derailing our climate and wiping out biodiversity; how we rear our livestock has a critical part to play and we certainly need to do it a whole lot better. Livestock, however, only consume a third of global cereal production so the humans directly eating or using the other two thirds of this harvest have a huge responsibility to ensure that their soya milk and ‘facon’ isn’t contributing to the destruction of our most precious ecologically rich regions.
So often, a switch to a vegan diet is heralded as inherently better for the planet with the assumption that this decision alone is making a significant difference. This is sadly not the case.
According to the EPA, in the USA the agricultural sector produced 6.5 billion tonnes of CO2 equivalent in 2017 (about half of this is from animal agriculture and half from plant agriculture) which equates to 1.1% of the global emissions.6
If everyone in the USA gave up meat, we wouldn’t simply remove these 0.5% global emissions the food we choose instead would still have an impact depending on what we selected. The potential effect on climate from our food choices is important but tiny compared to decisions around how efficiently we heat our homes and how many international holidays we take.7
In the UK our emissions associated with agriculture in 2018 were 45.6 million tonnes which accounted for 10% of UK emissions. 10% is significant, but, unlike many other sectors which are associated with luxuries and convenience; such as energy and transport, agriculture produces food for nearly ALL humans and is essential for survival regardless of your preference for vegan, omnivore or carnivore food.
I often hear people lament about the emissions from agriculture as if they plan to ‘opt out’ of participating in this dirty industry – good luck with that one!
So, in the context of the 49 gigatonnes of CO2 equivalent annual emissions the global impact to be gained from a change in diet in the UK is, by my estimate, no more than 0.0931% – so small it’s hard to accurately measure!8
That is certainly not a justification to just accept the status quo, rather a call to ensure that we stop deflecting the huge differences we can ALL make in our lifestyle by thinking we are ‘off the hook’ because we’ve swapped a meat burger for a veggie one.
There can be huge planetary gains made by the food choices we make, but the bigger impact is what can be gained from promoting food choices grown from regenerative agriculture that support the complex and interconnected functions of our ecosystem – way more elegant and impactful than the gains from the simple mathematical counting of emissions.
Carbon and Methane
Once upon a time in the USA there used to be a vast area of prairie (pasture) called the Great Plains. This story can be replicated on any of the world’s grasslands. This vast grassland was a giant ‘carbon sink’ with deep soils of up to 15% organic matter and was a rich habitat for thousands of different species of flora and fauna. Even through severe droughts, the plains supported somewhere in the region of 110 million wild ruminants. Up to 50-70 million of those were the giant one-tonne bison – the equivalent to about 2 small beef steers. We now, in the USA, have roughly the same number of domestic ruminants.9,10,11
Wild animals burp and pump too! So how come pre-industrialisation these ‘evil’ ruminant beasts didn’t wreck our climate?
Because nature created plants and animals – including ruminants – and she also created all the regulatory mechanisms to keep all gasses in balance and our climate cool. What’s gone wrong is that we have decoupled the cow from its natural environment and damaged the biosphere’s ability to regulate itself.
As carbon cycles though living organisms such as humans or cattle, it is ingested in the solid and liquid form of plants, or meat from animals that ate plants, and contributes to the growth and reproduction of that organism. Partly respired as CO2 and CH4 it is eventually released and recycled through the process of death and decay. An organism cannot excrete or exhale more carbon that is originally inhaled or ingested so the carbon in this scenario does not represent a net increase in the atmospheric load.12,13
Historically a larger portion of the carbon cycling through the biosphere would be in more stable solid states, such as humus in soils or the biomass of trees, than as a gas state in the atmosphere and this is contributing to the greenhouse gas effect. This issue can be simply resolved by using the very same mechanisms nature previously applied in times of high CO2 and CH4 levels – by increasing the longevity and effectiveness of photosynthesis across the planet. We now have tried and tested methods of managing grazing animals in ways that increase photosynthesis and rapidly sequester significant volumes of CO2 into stable solid forms as well as agroecological methods that mimic ecosystems.
When stored carbon is released in the burning of fossil fuels it’s added to the carbon that is being cycled through the atmosphere in its many states. Carbon that is taken from stored sinks then added to the cycling net carbon load should be considered differently to carbon already in the atmosphere that is simply changing states though living processes.14
Livestock on grassland and their various ‘ins’ and ‘outs’ are essentially climate neutral. It’s not until you start to move the livestock indoors and feed them grain that has been grown using fertilisers and other fossil fuels heavy inputs that a significant detrimental impact on the planet occurs.
The argument that grass-fed meat is worse for the planet because it takes longer to rear and is therefore belching more methane into the atmosphere is highly problematic too.
Methane is a potent greenhouse gas and is currently considered to have 28 times the ‘global warming potential’ of carbon dioxide. The methane produced by ruminants through their clever digestive system is why we pick out cattle as being ‘bad for the environment.’
But it has been acknowledged for decades that the methodology used to calculate the CO2 equivalent for methane is flawed and hides the fact that 1Gt CH4 has a strong warming influence when it is first emitted, which due to chemical reactions in the atmosphere, rapidly diminishes over a decade. Over the 100 years used to asses GWP100, the methane emitted has almost all been destroyed.
This means that unlike CO2 which continue to warm the planet over a hundred-year period at the same rate it did when released, methane should be treated differently in future to reflect a more accurate impact of methane – including enteric methane from herbivores and other living organisms – on climate.
“We don’t actually need to give up eating meat to stabilise global temperatures,” says Professor Myles Allen who led the study (meat production is a major source of methane). “We just need to stop increasing our collective meat consumption. But we do need to give up dumping CO2 into the atmosphere. Every tonne of CO2 emitted is equivalent to a permanent increase in the methane emission rate. Climate policies could be designed to reflect this.”15
It’s also critically important that we maintain the effectiveness of the Hydroxyl Radical ‘cleaning’ process that naturally and effectively removes methane from the atmosphere. How we manage land could play a hugely important role. A shift from grazed pastures towards conventional cropping systems in order to supply a demand for more plant foods could reduce the biosphere’s capacity to oxidise methane.16,17
Methane levels are rising at an alarming rate and the scientific community in disarray and disagreement as to the mechanisms that have led to this sudden rise.18
What can be agreed upon is that the atmospheric rise in methane has been caused by an increase in methane emissions, and or, a reduction in the effectiveness of the planet’s ability to oxidise and ‘sink’ the methane. Probably both.
There is evidence that the leaks from the fossil fuel industry are greater than have been reported and a strong indication that the increase in rice production along with an increase in the methane production from wetlands in the warming tropics is primarily responsible.19,20,21,22,23,24
What has recently come to light is that globally more than half of the increase in natural gas production has come from shale gas which happens to be somewhat depleted in 13C when compared to natural gas and is likely to be a significant contributor to methane increase puzzle.25
We can say with some confidence that enteric methane from livestock alone is not responsible for the statistically significant rise since 2007 in emissions, as the changes in livestock numbers in this period have been gradual and although ruminant numbers have increased in the developing world they have stabilised or reduced in the developed world. Cattle numbers saw their steepest increase between 2000 and 2006, when methane levels were flat.26
Another theory that is that we have reduced the capacity of the biosphere to perform the oxidisation process of methane through the ‘hydroxyl ion’ pathway and in aerated soils by methanotrophs.
The chemical reactions that ‘clean’ methane require water vapour and sunlight which is most reliably supplied by transpiring vegetation growing on covered carbon rich soils.27,28,29
By deforesting vast areas of the world, creating billions of hectares of bare eroding soil through overgrazing and ploughing land for crops, and ‘dimming’ sunlight through a veil of pollution smog and heat hazes, we have significantly altered the effectiveness of this critical climate cooling process.30
The huge potential for land management as a tool for supporting climate function is something being increasingly recognised by the IPCC and was highlighted in their recent report.31
Measuring the land use impact on the hydroxyl ion pathway is hugely problematic for scientists for many reasons including the dynamic nature of hydrology in space and time. This leads to greenhouse gas mitigation policy decisions being based on easy to measure and implement responses such as reducing livestock numbers.
Frighteningly, a switch away from livestock as a protein source could lead to many healthy carbon rich pastures that reliably transpire water vapour being ploughed up to create bare eroding, heat baked soil that only grows plants (crops) for a short period of the year.
We are losing soil and ecological function fast. An area half the size of the European Union is degrading annually. It’s time to stop arguing over if we should eat plant or animals, we need to support a new way to grow food that mimics natures climate cooling functions – agroecology and regenerative agriculture.32
This regenerative agriculture rebuilds soils and ecosystem services and helps regulate climate whilst growing both plants and livestock – the two are usually integrated to reflect the fact that in nature plants and animals are always intertwined to cycle nutrients and create complex and resilient food webs. The interconnections of nature are completely overlooked in suggestions to simply switch to a vegan diet as a way to fight climate change.
Regenerative agriculture has good current science to back it up – it’s the only truly sustainable way to produce viable yields of nutritious food and has been recognised by the Food and Agriculture Organization of the United Nations as a key solution.33,34,35,36
All other options that involve adding fossil fuels to our existing atmospheric load by relying upon highly ecologically damaging ‘manufactured’ fertility are simply a false choice that continues to externalise the true social and environmental costs of living beyond our planetary means and passes them to our children to pick up the tab.
Caroline
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