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Time to change our diet…

It is no secret that many of the animals we like to eat produce large volumes of methane. The plant diet of these animals is high in cellulose, which cannot be digested by the animal itself. However, ruminants have a symbiotic relationship with colonies of micro-organisms, called methanogens, which live in their gut and break down the cellulose into carbohydrates. These carbohydrates provide both the microbial community and the animal with an energy source but methane is produced as a by-product of this process.

It is said that some cows produce 600 litres of methane every day and over a year that is enough energy to drive an average car 2,000 miles!

Methane is 21 times more potent than Carbon Dioxide as a greenhouse gas and although it lasts for less time in our atmosphere it has a rapid and significant effect on global warming. Currently it is estimated that cows produce around 15% of global green-house gas emissions.

Future methane emissions are almost certainly expected to increase due to global food demand increasing from population growth. Developed nations already consume a lot of meat and it follows that developing nations will increase their meat consumption in future years.

So what can we do?

The table below shows kg Methane produced per year by the most popular animals we like to eat.

Animal typeCH4 (Methane)
Pigs1.5
​Goats5
​Sheep8
​Beef cows50.5
Dairy cows110.7

It suggests that we will have to curb our desire for beef and milk if we want to help reduce this ever increasing problem. Ideally we should eat more vegetarian food but if you want meat, it looks like pork in all its forms should be the number 1 on the list.

Other ideas to reduce methane emissions from cows are summarised in the table below (taken from Reay’s book Methane and Climate Change). These have been classified into short term (available now), medium term (available in 10 years) and long term (not commercially available for at least another 10 years). Unfortunately some of these suggestions have been disputed as they are not economically viable, especially in developing nations.

It suggests that we will have to curb our desire for beef and milk if we want to help reduce this ever increasing problem. Ideally we should eat more vegetarian food but if you want meat, it looks like pork in all its forms should be the number 1 on the list.

Other ideas to reduce methane emissions from cows are summarised in the table below (taken from Reay’s book Methane and Climate Change). These have been classified into short term (available now), medium term (available in 10 years) and long term (not commercially available for at least another 10 years). Unfortunately some of these suggestions have been disputed as they are not economically viable, especially in developing nations.

Short Term ​Medium Term ​Long Term ​
Reduce animal numbersRumen ModifiersTargeted manipulation of rumen ecosystem
Increase productivity per animalSelect plants that produce lower methane yield by the animals​Breed animals with low methane yield
Manipulate diet
Rumen Modifiers ​

If we are serious about reducing the causes of global warming and climate change, there has to be a wholesale change in our thinking, not just what we eat, but every part of our lives. Hopefully the Paris agreement may at least start this long and difficult process.

Graphics credit to @OatJack

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