Climate Change - non CO2 emissions.

When we think of climate change we picture smoke billowing from vast fossil-fuel power stations or exhaust fumes rising from cars in gridlocked cities. What most of us do not associate with climate change is a herd of cows, peacefully grazing on picturesque farms in the British countryside.

Now this is not to say cows cause climate change. However the intensification of farming practices that has occurred in recent decades most certainly can be attributed to climate change. So while we may think of cars and planes when we think of climate change, we perhaps need to take a closer look at agriculture.

Estimates of agricultural global GHG input vary between 19-29% but what is certain is that it dwarfs the transportation sector and is second only to the energy sector (Vermuelen et al, 2012). In the IPCC's Fifth Assessment Report, only non-CO2 GHG's are reported as agriculture is largely considered a 'carbon-neutral' process meaning it removes as much CO2 from the atmosphere (through photosynthesis) as it emits. These non-GHG emissions are not to be sniffed at.

The non-CO2 GHG's we are interested in are Methane (CH4) and Nitrous Oxide (N2O), the two next most significant GHG's to CO2 and included in the 'Kyoto Basket'.

NO2 emissions are a result of fertiliser applicationa and the (mis)management of manure. The inefficiences of nitrogen uptake in plants results in soils that are nitrogen-rich which readily provide nitrogen to microbes that use the element to produce energy for their growth and reproduction and as a byproduct release N2O. This process also occurs in the wet and warm conditions of manure management tanks so N2O emissions are produced by both crop and livestock oriented farms (Ussiri and Lal, 2013)

CH4 emissions are a product of enteric fermentation, rice cultivation and again manure management. Enteric fermentation relates to the normal digestive processes of farm animals, particularly cows and sheep, which produces CH4 as a byproduct that is exhaled or released by flatulence. This results in nearly a third of all human induced methane emissions (Bousquet et al, 2006). Rice cultivation is also a large human-induced source of CH4. Paddy fields are man-made wetlands and as such are the ideal environment for a host of microorganisms. The decomposition of organic matter within these wetlands produces excess methane which is released into the atmosphere. With such vast paddy fields in some areas of the world, rice cultivation now contributes 9% of all human CH4 emissions.

The total volume of non-CO2 GHG's in the atmosphere is significantly less than CO2 itself, however their ability to trap heat is far greater. Indeed CH4 has been reported to be 34x more effective at trapping heat than CO2 over a 100 year time scale (IPCC 2013), while N2O is yet 15 times more potent than this (Jeong et al, 2012)!

Predictions for future non-CO2 emissions do not look promising. As demands for food increase and diets change so does the scale of industrial farming. This results in more livestock and more fertilizer use. In order to keep pace with global food demands N2O emissions will likely increase 50% by 2020 (Mosier and Kroeze, 2000) and CH4 emissions will increase 60% (relative to 1990) (FAO, 2003).

How can we solve this issue? We can't demand a reduction in use of animal products can we? McMichael et al (2007) boldly concludes that an effective contraction and covergence policy would seek to

'(1) reduce greenhouse-gas emissions per unit of meat or milk produced; (2) reduce consumption of meat (especially ruminant red meat) and milk from the current high levels in high-income countries, with predicted health benefits; and (3) taper the rise in consumption of meat and milk in developing countries, also with predicted health benefits.'

With meat so embedded in many societal practices in high income countries and it seemingly unethical to prevent developing countries from increasing their meat consumption these policies seem implausible. However with the impacts of climate change becoming ever more real is it time we start looking at these more radical responses? This is something that I am intrigued by and am yet to completely establish my opinion on.

Check back in the next few weeks for more on the subject as I broaden my understanding and hopefully come to a conclusion on this problem of non-CO2 emissions.