Effects of Methane Gas Due to Animal Agriculture on Climate Change
Ever since man learned how to control fire, meat has been a primary source of food for people around the world. As humans adapted, we discovered how to domesticate certain animals in order to reap the benefits that such animals could provide. Today, meat is a staple of the average human diet. However, within the last decade we have been faced with the issue of global warming due to increased greenhouse gas emissions. Scientists from all over have been proposing many different, alternative routes to take in the future in order to reduce our emissions. Humans generally think of greenhouse gases (GHGs) as pollution, as something toxic and unnatural that comes out of car exhaust pipes and billows out of smokestacks above factories. However, in 2014, the United States Environmental Protection Agency (EPA) reported that methane emissions from cattle, swine, horse, sheep, goats, bison, and mules (all of which humans intentionally raise as livestock) came to about 9,518 kilotonnes, or 9,518,000 metric tons of methane (EPA Agriculture) in the United States alone. Not only is that a huge amount of methane to be released into the atmosphere by just one country in one year, but methane is considered by the EPA to have 25 times the global warming potential (GWP) that CO2 has (EPA Executive Summary). That means that 9,518,000 tons of methane have the environmental impact of 237,950,000 tons of CO2. Recently, these estimates have even been criticized as under-representing the impact of animal agriculture; an article written in 2009 by the World Watch Institute suggests that the numbers reported for overall animal agriculture under represent methane and CO2 emissions, and that in actuality animal agriculture accounts for roughly 51% of all annual GHG emissions (Goodland R. & Anhang J., 2009). The warming of our planet due to GHGs causes the release of even more GHGs at a dangerously quickening rate. If we want to attempt to address the issue of climate change in the immediate future, and as effectively as possible, then we need to start making a bigger deal about the carbon footprint created by animal agriculture.
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| Molecular model of a methane (CH4) molecule |
The Food and Agricultural Organization of the United Nations (FAO) estimated that in 2006, “7,516 million metric tons per year of CO2 equivalents (CO2e), or 18 percent of annual worldwide GHG emissions, are attributable to cattle, buffalo, sheep, goats, camels, horses, pigs, and poultry,” (Goodland R. & Anhang J., 2009). However, as the article from the World Watch Institute states, these numbers are drastically under-represented. The FAO decided to ignore livestock respiration in their calculations because they saw the CO2 exhaled by livestock as being “not a net source of CO2”, claiming that cow herds in fact perform a process of carbon sequestration because “the carbon consumed [via plant material] is stored in the live tissue of the growing animal” (Goodland R. & Anhang J., 2009). Not only is this false because “sequestration” refers to the deposition of a gas into a vault, where it is stored in a stable state for long periods of time, but because the plant material that is fed to the cows is usually grown on forest-cleared fields, which originally sequester much more CO2 than can be claimed for cows (around 200 tons of carbon per hectare). In their calculations of the GHGs produced by animal agriculture, the FAO overlooked livestock respiration (which produces about 8,769 million metric tons of CO2 annually), as well as land use for livestock (both for keeping livestock and for growing their food), for which the CO2e was about 2,670 million tons (Goodland R. & Anhang J., 2009). It is important to recognize the amount of CO2 emitted from livestock because of the effect that warming has on existing methane deposits in the Earth, which will be discussed.
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| Table from "Livestock and Climate Change" article by Goodland and Anhang |
When considering the effects that carbon-related molecules have on the atmosphere, it should be noted that methane (CH4) has a half-life (rate of decay) of only about 8 years when in the atmosphere, while carbon dioxide (CO2) has a half life of at least 100 years (Goodland R. & Anhang J., 2009). This is significant because it means that reducing methane emissions would have a much more immediate effect in terms of slowing climate change than any attempts to prevent CO2 from entering the atmosphere. The FAO currently examines the effects that methane has on the atmosphere within a 100-year span of time; however, due to methane’s short half-life, this is inappropriate. The World Watch Institute suggests that methane’s impact should instead be examined on a 20-year span due to its short half-life, which would increase its GWP from 23 times that of carbon (the measurement from 2006) to 72 times. This would adjust the FAO’s estimation of methane from livestock accounting for 3.7% of worldwide GHGs in 2006 to 11.6% of worldwide GHGs (Goodland R. & Anhang J., 2009), as well as adjusting our earlier calculation of the United State’s methane emissions from 2014 from being 237,950,000 tons of CO2e to 685,296,000 metric tons of CO2e, nearly tripling the number reported by the EPA (EPA Agriculture).
The methane and CO2 released due to animal agriculture is obviously an issue. It contributes to the weakening of the ozone, allows for more heat to be trapped within our atmosphere, and could be remedied by nothing more than consuming less meat and dairy (since cows are the highest contributors to these emissions). However, these GHGs don’t just add to the total count of emissions and stop there; what if the release of methane (and other GHGs) spurred the release of even more methane? Within the last few years, scientists in Russia have noticed something rather alarming about the region of Siberia: mysterious giant craters. After visits to some of these giant holes were recently conducted, “scientists from the respected Trofimuk Institute of Petroleum Geology and Geophysics insist the process by which a series of craters formed was caused by the melting of gas hydrates and the emission of methane.” (Liesowska A., 2015) These scientists believe that the craters are a result of the melting of gas hydrates containing methane (a combination of water and methane at high pressure and low temperature) (OSU, 2006), which was at one time sequestered from the atmosphere and stored underground in a stable state. Due to rising global temperatures, this once-stable solid hydrate has begun to “transition from a solid to a gaseous state” which causes the volume of methane to “increase about 150 times”(Liesowska A., 2015), which explains the explosions that cause the craters to appear. If these scientists are right, and these methane deposits have only just begun to burst to the surface, then humans need to take action as soon as possible to prevent further global warming; otherwise, the methane trapped beneath the melting ice in Siberia could be released, allowing even more massive deposits of methane to permeate the atmosphere and further contribute to climate change.
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| Crater discovered in Siberia believed to have been caused by expanding methane gas |
In the last 30 years alone the Earth has experienced a mean surface temperature increase of 0.6 degrees Celsius, and it is predicted that the temperature will continue to rise another 4 degrees Celsius by the year 2099 (HSI, 2014). This increase in global temperatures has been related to the melting of glaciers, the rising of sea levels, and the extinction of many species of animals. The Intergovernmental Panel on Climate Change (IPCC) predicts that, at the current rate that temperatures are increasing, droughts caused by global climate change will cause up to 250 million people worldwide to experience water shortages by 2020, while a fall in food production due to lack of water could result in food shortages for 130 million people across Asia by 2050 (HSI, 2014). Increasing temperatures will also cause sea levels to rise, destroying coastal homes and habitats, and allow for gas hydrates containing methane to melt, which would cause large scale explosions and create deep craters in the Earth’s surface. With dietary trends currently shifting toward increases in the consumption of refined fats, oils, and meats, coupled with an increasing population, it is estimated that global agricultural GHG emissions could increase by 80 percent by 2050 (Clark M. & Tilman D., 2014). The time to reduce our carbon footprint by cutting back on animal agriculture is now; if we don’t act soon, we could very well come to a point where it is simply too late to prevent global disaster from wreaking havoc on society.
Bibliography:
Clark M. & Tilman D., 2014. “Global diets link environmental sustainability and human health.” Nature, (vol. 515) doi:10.1038/nature13959. http://www.nature.com/nature/journal/v515/n7528/full/nature13959.html
Floyd M., 2006. “Researchers Discover Rich Methane Field Off India, But Energy Potential Still Unknown.” Oregon State University.
Goodland R. & Anhang J., 2009. "Livestock and Climate Change." World Watch Institute. http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf
Humane Society International, 2014. “An HSI Report: The Impact of Animal Agriculture on Global Warming and Climate Change.” http://www.humanesociety.org/assets/pdfs/farm/hsus-the-impact-of-animal-agriculture-on-global-warming-and-climate-change.pdf
Liesowska A., 2015. “Danger of Methane Explosions on Yamal Peninsula, scientists warn.” The Siberian Times. http://siberiantimes.com/science/casestudy/news/n0415-danger-of-methane-explosions-on-yamal-peninsula-scientists-warn/
United States Environmental Protection Agency. "U.S. Greenhouse Gas Inventory Report: 1990-2014 - Agriculture." https://www3.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2016-Chapter-5-Agriculture.pdf Web. 30 Mar. 2016.
United States Environmental Protection Agency. "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2013 – Executive Summary." https://www3.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2015-Chapter-Executive-Summary.pdf Web. 30 Mar. 2016.
