Global warming is average rise in the temperature of the earth; this happens over a long periods of time and is most influenced by greenhouse gases. Basically greenhouse gases help the earth retain heat by trapping most of the heat that is emitted by the sun. Due to increase in the population and industrialization, the amount has increased over the years. The most common greenhouse gases are carbon dioxide, methane and nitrous oxide; with carbon dioxide being the most abundant greenhouse gas. Gases like carbon dioxide are sequestered by forests which use them for producing their food through photosynthesis and some end up being absorbed by the ocean; but this process has over the years been affected by rate of deforestation thereby altering the balance of carbon dioxide on the planet. The different greenhouse gases have different global warming potentials (GWP) or radiative efficiencies. Despite carbon dioxide being the most abundant greenhouse gas, Methane has the greatest GWP; it is 28 times more potent than carbon dioxide. The source of methane is mainly from anaerobic respiration of organic waste; and food waste being a major contributor.
A book by Paul Hawken “Drawdown-The Most Comprehensive Plan to Reverse Global Warming” highlights and ranks the most effective solutions to combat global warming. Firstly, the term Drawdown translates to the point at which levels of greenhouse gases in the atmosphere stop rising and start steadily declining, thereby reversing global warming. Reducing food waste is rank as the number 3 solution. Research shows that food waste contributes roughly 8% of global emissions; this is largely from the methane that is released through breakdown of the organic waste.
In Zambia the solid waste is collected by local authorities or private operators and thereafter disposed at a dumpsite. In the presence of engineered landfills, the emission of methane is significantly reduced due to the presence of oxygen which results in aerobic digestion of waste. However, in Zambia we largely have dumpsites usually located in the outskirts of town and in some places like Lusaka it is closely located to townships. Dumpsites are the major emitters of methane since anaerobic respiration is synonymous to non-engineered landfills. Additionally, with the coming of the entrepreneurial age, any agricultural commodity that is deemed as profitable becomes “the it” for every farmer; take for instance the rise of the tomato farming regime; it only took a few farming seasons and the commodity was everywhere like air (the band wagon effect). The result was a massive food wastage, because the supply exceeded the demand. Likewise, in most traditions it is believed that a person is only satisfied if they leave food leftovers, this practice only increases the amount of food waste. Most professionals eat out for lunch, and surprisingly the famous nshima (maize meal) canteens will be those that offer a mountain of nshima and a lot of relish. The amount of food leftovers often become a measure of how good a restaurant is. At house household level, we buy more bread, vegetables, fruits and food stuff that we really don’t need; which only end up being throw away after a week after going bad. This prestige norm of “the bigger the trolley, the better” only results in food wastage.
As part of a short study on reducing food waste with Cornell University’s Climate Change fellowship, I surveyed 22 local individual in Lusaka from various backgrounds to try and quantify how much food waste they generated and its contribution to methane production. The study indicated that 77 million kg of food waste per year in Lusaka alone is generated with the current trend of food wastage. This amount of food waste is capable of producing 6 thousand tonnes of methane gas. To put it into perspective, that amount of methane if convert into electric energy can power up to 40,000 households for a year! But alas these emissions go in the environment and adds to global warming.
Going forward; we as citizens need to be the aware of the various causes of climate change and try to help on those that we can. Over the years the focus has been on tree planting programs which very few people have participated in as a climate mitigation measure. Although, it is hard to change the social and cultural trends attached to quantities of food consumed, it is imperative that we change our lifestyles on an individual basis to protect our planet. There is also need for the Government to invest in engineered landfills, climate change literacy, more rigorous tree planting programs and industries to convert food waste to methane, which can further be used for electricity generation or as a raw material for natural gas operated heating systems.
(Chewe Chishala, Climate Change Enthusiast)