Why going vegan won't save the world ...

... but not wasting food, changing what meat we eat and altering our lifestyles will certainly help.

Some proponents of a vegan lifestyle state that if the world's population were to turn vegan we would save the world from climate change and cite the following reasons why they believe this is the case:

1. Livestock farming (especially for beef) produces methane (a greenhouse gas) via the natural digestive process of the animals ie cow farts. Methane is 20 times more potent as a greenhouse gas than CO₂.

2. Areas of rainforest are being felled at an alarming rate with the cleared land used for cattle farming.  The forests previously would have absorbed CO₂ and when the soil is cultivated before being turned to pasture, it releases nitrous oxide and methane that are both stored in the soil. Nitrous oxide is 300 times more potent than CO₂ as a greenhouse gas.

3. A hectare of land can feed many more people if it produces plants as opposed to animals.

Sounds convincing but there is another side to these arguments.

1. Methane from livestock

It is estimated that livestock produce 5.5% of all greenhouse gases, although in Argentina where livestock farming is the main land use this rises to 30% . But what other processes produce greenhouse gases and in what percentages?

Power plants - 25-30% ie using fossil fuels to produce energy.
Residential buildings - 11% through heating, air conditioning and power consumption.
Road transport - 10.5% and although cars now have lower emissions car numbers are rising rapidly
Deforestation and land use change - 10.3%. The land is not only cleared for livestock but also for palm oil plantations and other crops.
Losses during energy production - 8.3%.
Commercial buildings - 7% mainly through air conditioning, electrical devises and power to run computers.
Production of cement, ceramics, glass - 6%. To produce these new materials from raw materials uses a lot of energy with the associated emissions.

Then we get to livestock at 5.5%.  What these figures don't show is how much of each type of greenhouse gas is produced. For livestock this is primarily methane which is 20 times more potent than CO₂. This does make this 5.5% figure appear worse until you realise that methane does not last as long in the atmosphere and breaks down into CO₂. Yes, this is still a greenhouse gas and yes, methane production from livestock is a huge problem but it needs to be in the context of other emissions.  Livestock farming certainly produces high amounts of greenhouse gases but other processes, as detailed above, produce far more.

2. Rainforest clearance for livestock farming

Forests are not only being cleared for livestock production.  In Asia and increasingly in Africa virgin rainforest is being cleared for palm oil plantations.  Palm oil is deemed a wonder oil as it produces higher amounts of oil than any other oil producing plant. It is used extensively in processed food, including vegan food.  Other areas of cleared forest are used to grow soya beans which are also used widely in vegan food.

If farmers were no longer raising cattle they would have to shift to some form of crop growing on land that was previously pasture.   At present ploughing existing agricultural land releases 4.4% of global greenhouse gas emissions, mostly in the form of nitrous oxide, a greenhouse gas that is 300 times more potent than CO₂.  Furthermore to produce consistently high yields, crops have to be fertilised. Without animals to provide manure (the pre-industrial method of maintaining soil fertility levels) farmers will have 2 options - to either grow plants specifically to be composted or to use artificial fertilisers. In reality farmers will not turn over a percentage of their productive land to make  plants for compost when they can buy artificial fertilisers.  Animal manure is not without its problems but the production of artificial fertiliser produces large amount of greenhouse gas emissions.

And there's more. Microbes in the soil convert fertilisers (manure and artificial) into nitrous oxide and this rate has been seen to increase in an exponential manner when farmers add more fertiliser. Nitrous oxide also gets into the atmosphere when there is surface run off of polluted water and soil erosion. So whilst livestock, especially cattle, produce methane, farming crops results in high level of the more potent nitrous oxide being produced.  

Livestock are also fed soya, a crop that is increasingly grown in recently deforested land.  However if livestock farming were to stop it is likely that this soya would be used for other purposes, such as biofuel, human food in greater amounts and a variety of industrial processes.  If not soya, farmers would grow other crops, perhaps those to be used to produce plant based plastics to replace plastics made from fossil fuels.  Even if the land were not to be farmed, it is not possible to replant rainforests in the way that temperate woodlands can be due to soil degradation and other factors. Land that previously supported rainforest can regenerate into a form of forest but which supports less diversity (plant and animal) and it is estimated that to return to its original form could take hundreds or thousands of years.

3. A hectare of land can feed many more people if it produces plants as opposed to animals

Livestock that are intensively farmed do not simply graze on the grass underfoot and are fed additional food such as maize and soya.  It is argued that this maize would be better fed directly to humans or the land used to produce food for humans.  This in itself is a very simplistic statement and does not take into account that humans would not only want to eat maize but would want a variety of plants, many of which produce much lower harvests than maize, especially those that provide the protein needed in a balanced diet.

Any agricultural practice when undertaken as a large scale monoculture comes with much greater environmental damage than traditional small scale mixed farms.   There is a loss of local natural habitats and monocultures rely heavily of pesticide use.  Pesticide production releases emissions and there are many problems of pesticides affecting natural ecosystems and human populations. With the world's population eating a vegan diet there would continue to be monoculture agriculture.

One final point, not all land can be used to produce crops. This land however can sustain populations of animals, especially sheep and goats which are vitally important food sources for populations in  many parts of the world such as sub Saharan Africa.  Even in temperate regions there are many areas such as moorlands and wetlands that cannot produce crops but are farmed successfully for livestock.

Summary

Whilst is is beyond doubt that livestock farming produces large amounts of methane and rainforests are being cleared for more livestock to be raised, switching to an all crop based agricultural system would be accompanied by its own problems of greenhouse gas emissions, pollution, deforestation etc.  Eating less meat overall and switching to pork and chicken would lead to fewer emissions as these animals produce lower levels of methane.  Wasting less food would be hugely beneficial. It is currently estimated somewhere between 30-50% of all food produced is wasted both on the farm, in transport, during processing and in the home.  Landfill produces 3% of global greenhouse gas emissions, almost all as methane from rotting wasted food.

The reality is we need to radically re-assess how we eat and more importantly how we live.  There are other more damaging processes such as energy production, road transport, buildings that have more negative effects than eating meat.  We certainly should be eating less meat, especially intensively reared beef and we need to be much less wasteful of our food. Switching humanity to a vegan diet may be less harmful overall but it will not solve the world's environmental problems and will result in a shift from one set of problems to another.

Further reading and sources:

• Nitrous Oxide 
• Environmental and social impacts of soy
• Why veganism isn’t as environmentally friendly as you might think
• Nutrition per hectare for staple crops 
• 15 sources of greenhouse gases