Review/Oorsig Volume 22, Issue 04 - Page 13

Volume 22 • Issue 04 • 2018 Throughout history, there have been significantly more ruminants on the planet than now which played an active role in reducing atmospheric greenhouse gases (GHGs) through their grazing and subsequent carbon sequestration (2). When in balance, methane is not the evil it’s made out to be – as with most things in nature, it’s only a problem when it gets out of balance. ‘New’ carbon To recap, a range of naturally occurring processes have cycled and recycled a finite amount of carbon for millennia, and will continue to do so. Many of the environmental problems we are now experiencing result from human activities that have added – and continue to add - ‘new’ carbon to the system. Fossil fuels The exponential increase of the human population and our seemingly unquenchable thirst for growth in all aspects of life, has resulted in our blindly burning through vast quantities of stored carbon in the form of fossil fuels. We are on course to release into the atmosphere 60 million years’ worth of this long since sequestered carbon in just 150 years. Once released into the atmosphere, it becomes part of the cycling carbon, putting enormous pressure to the earth’s ability to cycle it through natural processes. When those processes are overloaded, the levels of CO2 and methane in the atmosphere rise. 150 years ago, CO2 levels were a comfortable 280 parts per million (ppm); in 2017 they peaked at 410ppm, a dramatic increase (2). Methane levels too have seen a rapid rise, doubling since the industrial revolution (9). These increases in carbon dioxide and methane, resulting directly from human activity, are having significant consequences for the climate because of their role as greenhouse gases (GHGs). Greenhouse gases: from protection to poison The part of the atmosphere nearest earth, the first 10km or so, known as the troposphere, is made up of around 78% nitrogen and 21% oxygen, with small concentrations of other trace gases, important ones being carbon dioxide and methane. These are important because, along with water vapour and nitrous oxide, they are greenhouse gases. Vital for keeping the earth inhabitable, GHGs create a protective shield (‘greenhouse’) around the troposphere that keeps the earth warm enough to sustain life as we know it. Yet what has been protecting us is now in danger of poisoning us. The concentration of GHGs is increasing so that instead of ensuring the essential warming of the earth, they are causing overheating… and climate change. Cows cycle carbon: fossil fuels add carbon Those seeking to influence our food choices away from animal products often report on climate change by conflating the carbon that is already in the atmosphere with the carbon that is being added to the atmosphere as a result of human activity. While cows cycle carbon, fossil fuels add carbon. It’s essential to understand the difference. Pie charts representing global methane emissions frequently show one 25% slice for methane from enteric fermentation in cattle and then equate it with another 25% slice for methane from the mining and burning of oil, coal and natural gas. This is either a gross misunderstanding of the carbon cycle or a deliberate attempt to confuse the public. Methane from cattle is made from carbon taken from the atmosphere. It is not biochemically possible for cattle to emit more carbon than they consume in their diet. Cows can only cycle carbon. In contrast, methane from the mining and burning of fossil fuels is made from storedcarbon and it adds carbon to the atmosphere. This makes the size of the whole pie chart bigger, not just a slice. It’s not the cow, it’s the how This is not to say that all cattle farming is harmless. Quite the contrary, modern intensive livestock farming practices use large amounts of fossil fuels and feed animals human-edible crops, like grains and soya, with the aim of producing more output more ‘efficiently’. This approach to ‘efficiency’ measures litres of milk or grammes of protein produced per area of land in the shortest possible period of time. However, when all external costs are taken into account - the fossil fuels used; the soils damaged; the carbon released in the production of crops to feed the animals; the greenhouse gases emitted and the chemicals released into the natural environment - such modern, intensive farming practices can be seen as inefficient and unsustainable (11). Again, it is the conflation of carbon sources and disregard for the off-setting of carbon sequestration, that bury the sustainable farming practices within the general criticism of industrial practices. And so for cows: it’s not the cow herself 13