by Gretchen Kurtenacker, MS, MLS(ASCP), MT(AMT), NTP(NTA)
Part 1: The Problems
Figure 1. Global average temperature, (NASA, 2018)
Introduction
The UN Intergovernmental Panel on Climate Change (IPCC), predicts, based upon current levels of greenhouse gas (GHG) emissions, that temperatures will increase to 1.5 degree Celsius above pre-industrial levels sometime between 2030 to 2052, (Intergovernmental Panel on Climate Change [IPCC], 2018). We have already increased one degree. We know that as average citizens we need to reduce our dependence on fossil fuels and move towards clean energy. In response, solar panels have been put on rooftops, hybrid and electric cars purchased, bike-share programs introduced globally. However, not enough emphasis is put on the contribution agriculture has on climate change or what consumers can do to minimize the impact of agriculture.
Industrial agriculture and massive food production systems that disperse food around the globe are a significant contributor to GHG emissions. Our food choices can have an environmental impact, but we need to uncover fact from fiction as to what are the more environmentally friendly farming methods, which is the aim of this paper. What food choices can we make that would reduce our contribution to GHGs?
What Climate Change is and Why We Should Care
Climate change is the term used to describe the general warming of the earth’s atmosphere caused by ever increasing greenhouse gases, and the collateral damage such warming brings. Since mid-last century, warming due to an increase in the heat trapping gases of our atmosphere, has occurred at an unprecedented rate due to population increases and industrial activities of man such as burning of fossil fuels, deforestation, and massive monoculture farming, (Drake, 2015). This warming is life threatening. Rises in sea level from melting glaciers, snow, and ice, acidification of the oceans, greater variability in rainfall, increasing flooding in some areas with drought in others, fires, and extreme weather have already begun and are predicted to increase dramatically, (Environmental Protection Agency [EPA], 2017). In addition to weather variability, climate change is triggering the movement of once tropical diseases such as leishmaniasis and trypanosomiasis to more temperate zones. Tick-borne encephalitis and Lyme disease have occurred as far north as Russia and Sweden, respectively, (Welch, 2017). Also on the move are mosquito borne viral infections such as malaria, Dengue fever, and Chikungunya. Warmer waters are seeing Vibrio outbreaks occurring in Northern Scandinavia and Alaska, (Welch, 2017). And it’s not just humans being subjected to these ills. Species loss is occurring at what is estimated as 100 times faster than normal, (Drake, 2015). Species extinction is not entirely due to global warming, but the drivers of global warming are also driving species loss: human overpopulation, chemical monoculture farming, deforestation, loss of habitat, etc. Referred to as the 6th extinction event, projections indicate that by 2050, 15-37% of known species will be extinct, (Drake, 2015), thus, the global community should be scrambling to halt and reverse the activities driving climate change and species loss.
What are Greenhouse Gases and Where are They Coming From?
Greenhouse gasses (GHGs) are so called due to their ability to trap heat in greenhouses allowing produce to grow inside despite frigid temperatures outside. In our troposphere, the atmospheric layer closest to Earth, heat from the sun is trapped and dispersed by greenhouse gasses which act like insulation keeping Earth at an average +14 centigrade (57.2F), as opposed to -18 degrees centigrade (-0.4F) without the greenhouse effect, (Climatica, 2019). However, as the amount of GHGs increase, so do Earth’s temperatures. Theses GHGs consist mainly of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as man-made fluorinated gases, (Environmental Protection Agency [EPA], n.d.-a). CO2, the predominant GHG (Figure 2), is derived from the burning of fossil fuels such as coal, oil, and natural gas, burning of organic materials such as trees and solid wastes, (EPA, n.d.-a). It is also produced from chemical reactions, most notable, the manufacture of cement, which may not sound impressive, but consider that cement is the binder in concrete and concrete is the most widely used man-made material in existence, (Rodgers, 2018). Cement contributes 8% of the global CO2 emissions. Rodgers (2018) compares it to a country where it places as the 3rd biggest contributor to CO2 emissions, just after China, the 1st and the U.S., the 2nd. Methane (CH4), (Figure 2) is produced from production of coal, natural gas, oil fracking, livestock, and is emitted from landfills as solid waste degrades, (EPA, n.d.-a; Leahy, 2019). Nitrous oxide (N2O) (Figure 2) is another byproduct of the burning of fossil fuels, burning of solid wastes, and certain industrial activities as well as in the treatment of wastewater, (EPA, n.d.-a). The fluorinated gases (F-gases) (Figure 2) are hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, (EPA, n.d.-a.). Hydrofluorocarbons are refrigerants that replaced chlorofluorocarbons which were destroying the ozone layer. Perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are used in electronics and metal processing such as aluminum and magnesium as well as in semiconductor manufacturing, (European Commission, n.d.).
The effect these GHGs have on global warming depends on three basic properties: How much there is, how long each one sticks around, and how powerful the GHG is, (EPA, n.d.-a). These properties determine each gas’s global warming potential (GWP) and are reported as CO2 equivalents (CO2-eq). To calculate the CO2 equivalent of the other GHGs, the amount of it that is emitted is multiplied by its GWP. In 2017, the U.S. Environmental Protection Agency (EPA) estimated the U.S. GHG emissions at 6457 million metric tons (metric ton = 2205 pounds) of CO2 equivalents, (Figure 3). In the U.S. transportation, electricity generation, and industry contribute the most GHGs while agriculture is estimated at contributing 9.1% (Figure 4)
Figure 2. Global greenhouse gas emissions per IPCC 2014 (EPA, n.d.-b)
Figure 3. U.S. greenhouse gas emissions in 2017, (EPA, n. d.-c)
Figure 4. U.S. GHG emission by economic sector in 2017, (EPA, n.d.-d)
Prior to the industrial age, GHGs remained stable as the amount that were sequestered by natural processes (sinks) equaled the amounts that were generated (sources) through natural activities such as the weathering of rocks, volcanic eruptions, and biological life cycles. Ice cores allow us to ascertain the GHG levels over the last 800,000 years (Luthi et al., 2008). By testing air bubbles trapped in ice cores, scientists can see that for the last several hundred thousand years, GHGs have never approached the levels we see today, (Climatica, 2019). Prior to the industrial revolution, CO2 varied from 260-280 parts per million (PPM). Since, they have risen to over 400 ppm with the majority of that within the last 50 years, mostly CO2 which has increased by 80%, (Climatica, 2019).
What is it About Agriculture that Drives Global Warming?
As noted, the drivers of global warming are predominantly the burning of fossil fuels for energy, transportation, and industry, deforestation, and industrial agricultural practices. Burning of fossil fuels and deforestation make sense, but how does agriculture contribute to climate change?
Soil is a natural carbon sink. Plants pull carbon dioxide from the air during photosynthesis wherein it reacts with water to form glucose for energy, thus the carbon becomes part of the plant biomass. Some carbon is exuded from the plant roots into soil as sugars which drives microbes to release mineral nutrients that the plant roots uptake. Additionally, when the plant dies, it decomposes returning its nutrients to the soil and becomes soil organic matter (SOM). (Montgomery, 2019). This organic carbon-based matter is broken down by bacteria to create soil organic carbon (SOC). The natural balance of carbon release and sequestration is upset by farming methods that till the earth, allow it to lay bare, or repeatedly grow massive monocultures. (Barker & Pollan, 2015).
More specifically, plowing or tilling for weed control to facilitate spraying and harvesting, aerates the soils exposing it to oxygen with which the carbon reacts to form carbon dioxide. Further, exposing the soil to oxygen alters the microbial diversity in the soil to one that favors organisms that convert organic matter into yet more carbon dioxide. Chemical fertilizers and herbicides allow farmers to let fields lay bare during off season which again exposes the soil to oxygen and allows SOC to react, creating CO2 and depleting soil health in addition to promoting erosion and poor water retention. (Barker & Pollan, 2015) So, while modern industrial agriculture increased food production, it came at a steep environmental price. According to Barker and Pollan (2015), one third of the carbon in the atmosphere came from the soil due to the unsustainable and environmentally destructive practices of modern industrialized farming. It has been estimated that globally cropland has lost 20-60% of its carbon, (Montgomery, 2019) and in the U.S. typical industrial farmland has lost 50 to 70% of its carbon, (Barker & Pollan, 2015).
Additionally, the machinery used in modern agriculture burn fossil fuels contributing to GHGs. Monocultures result in reduced biomass (nutrients and carbon) to the soil and therefore reduced yields, and reliance on synthetic fertilizers, (Jarecki & Lal, 2003). Synthetic nitrogen fertilizers are then used to make plants grow despite depleted soils producing crops that may have decreased nutrient density, (Guo, Nazim, Liang, & Yang, 2016; Noulas, Tziouvalekas, & Karyotis, 2018; Scheer & Moss, 2011). About one third of the global cropland is already degraded to the point that farmers have abandoned it, termed desertification. David Montgomery, Professor of Earth and Space Sciences at the University of Washington and author of the book, “Dirt: The Erosion of Civilizations” explained that “soil degradation undermined societies around the world, from the ancient Greeks and Romans to the U.S. Dust Bowl of the 1930s.”, (Montgomery, 2019). Syria, Libya and Iraq are also living with historically degraded soils, (Montgomery, 2017). The continuation of degrading the soil will make feeding the predicted 9.7 billion people in 2050 more challenging, (United Nations, 2019, June 17). Add to that the harsh and unpredictable weather of climate change, and food security in 2050 looks worrisome.
Deforestation to create more land for farming is also a significant contributor to GHGs as the trees removed were clearing CO2, and once removed, are not. Further, in the removal of the forests, more fossil fuels are burned in transporting removal equipment and the wood. If “slash & burn” techniques are used, where after the sellable wood is removed, the saplings and brush are burned to clear the land, the burning generates still more CO2. Despite hundreds of companies committed to eliminate deforestation from their supply chains, 70% of deforestation is due to food production in some way, (Riley, 2017). The UN had hoped to halt deforestation by 2020, (Riley, 2017).
This highlights the problem of food trends. Food fads such as paleo non grain flours from coconut and almonds, vegan cheese and ice cream from cashews, avocado everything from vegan desserts, toasts, to oil, non-dairy mylks of soy, almond, cashew, and vegan protein replacers such as soy and quinoa have generated high demand. Pristine tropical forests are slashed, burned and turned into avocado, palm, coconut, cashew, etc. plantations, (Neilson, 2017). Each of these ingredients has its own horror story, from agricultural pollution to human rights abuses, however this report will look at just two. The increase in avocado sales has spurred much deforestation in central and southern Mexican forests, (Boch, 2016; Callabero & Flores, 2019). According to Caballero and Flores (2019), in 10 years, avocado orchards increased 162% in Michoacán, 511% in the state of Mexico, and nearly 1001% in Jalisco. U.S. consumption of avocados increased 440% in the last couple decades, 80-90% from Michoacán which resulted in somewhere between 14,800 to 19,800 acres of deforestation, some of it illegal, (Callabero & Flores, 2019). Michoacán is a biologically critical area as the winter migration home of the Monarch butterfly (Figure 5) whose numbers have greatly reduced since the early 2000’s, although on a slight uptick in recent years. Illegal deforestation to grow avocados also threatens several other endangered species, such as the transverse volcanic leopard frog, arboreal alligator lizard, cougar and the axolotl, (Callabero & Flores, 2019). The avocado trees are thirstier than native pine forests, requiring four to five times as much water which means less water return to the local mountain streams upon which the forest plant life and animal life depend, (Callabero & Flores, 2019; Nelson, 2016). While avocado trees do capture carbon, they sequester four times less that native pines per hectare, (hectare = 2.471 acres) (Callabero & Flores, 2019). And if that wasn’t enough, chemicals used in the avocado groves may be impacting the local population who reportedly complain of sneezing during fumigation, as well as other breathing and stomach problems, (Covarrubias, 2016). As avocados are grown in mountain orchards, chemicals wash into ground water, streams, and other bodies of water that downstream communities depend on, (Covarrubias, 2016).
Figure 5. Monarch butterflies hibernating in oyamel trees outside of Angangueo, Michoacan, Mexico, (Bfpage at English Wikipedia, 2000).
As for palm oil, it is estimated that 90% of the natural forest habitat of orangutans has been destroyed generating predictions of extinction within 10 years, (Neilson, 2017). These fad foods average 4000 miles transport to reach the U.S. markets. How significant this is, depends upon several factors, but generally, sustainably produced local foods generate less GHG than those flown from halfway around the globe.
What is it About Livestock that Drives Global Warming?
In 2006 the UN issued a particularly damning report called, “Livestock’s Long Shadow”. In part two we will see that when properly managed, livestock are actually climate savers, however, the report, while later corrected in 2010, (Jamieson, 2010) has fueled the, “eat less meat” trend. The 2006 report concluded that livestock contributed 18% of the GHGs as well as water scarcity and land desertification. 18% was more than the CO2 emissions of the transportation sector at that time, (FAO, 2006). Further, they claimed that livestock generated 65% of human-related nitrous oxide, which comes from manure and has 296 times the GWP of CO2. Livestock also contributed 37% of the anthropogenic methane with 23 times the GWP as CO2, (FAO, 2006). The methane is predominantly generated from the first stomach of ruminants and released via eructation (belching).
Additionally, it was estimated that livestock used 30% of the global land which included 33% of arable land (suitable as cropland) that is used to grow livestock feed, (FAO, 2006). In some countries such as in South America, forests were cleared to make room to raise livestock which is a double insult to climate change since the trees, which were natural CO2 scrubbers, were replaced by methane producing animals. Adding to this dilemma, estimates indicate that the consumption of beef alone is projected to double by 2050, (LeVaux, 2015).
Climate Change Projections and Goals
The Intergovernmental Panel on Climate Change of the United Nations (IPCC), which researches climate change, makes projections, and suggests mitigation strategies, estimates that in the 21st century the planet will warm between 0.5°F to 8.6°F degrees Fahrenheit, (EPA, 2017). This may not seem like much, but it will drastically alter earth. This increase will not be uniform over the earth, but rather experienced more in some areas than others. So, while some people and places will be minimally affected, others will be decimated resulting in massive poverty, hunger, and homelessness. For example, so far, the biggest increase has been in the Artic during what should be its cool season, thus the drastic melting of polar ice and shrinking glaciers, (Buis, 2019). According to Oddur Sigurðsson, a glaciologist at the Icelandic Meteorological Office, Iceland has already lost 56 of its 300 glaciers and further predicts they will all be gone within 200 years, (Engel, Gardiner, & Werner, 2019). In 2014, the Icelandic glacier, Okjökull (Ok), was declared dead, for which Iceland recently held a symbolic funeral and erected a plaque:
A letter to the future
Ok is the first Icelandic glacier to lose its status as a glacier.
In the next 200 years all our glaciers are expected to follow the same path.
This monument is to acknowledge that we know what is happening and what needs to be done.
Only you know if we did it.
August 2019
415ppm CO2
(Bowler, 2019)
In Part 2 we will look at agriculture solutions to combat climate change, revisit the debate about livestock and climate change, and make suggestions to guide consumers toward food choices that mitigate climate change.
Gretchen Kurtenacker, MS, MLS(ASCP), MT(AMT), NTP(NTA) is a Medical Laboratory Scientist who holds a B.S. from the University of Cincinnati in Clinical Laboratory Science, an M.S. in Health & Nutrition Education from Hawthorn University and is currently working on a D.Sc. in Holistic Nutrition, also from Hawthorn University. Her interests include food anthropology, food & the environment, and elder nourishment.
Gretchen lives in the First Hill neighborhood of Seattle where she enjoys the incredible selection of local, artisanal, sustainable foods available within walking distance of her home.
References for Part 1
Climatica (2019). Greenhouse gases, Retrieved from
Intergovernmental Panel on Climate Change. (2018). Summary for policymakers. In: Global warming of 1.5°C. An IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Retrieved from https://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf
Jarecki, M. K., & Lal, R. (2003). Crop management for soil carbon sequestration. Critical Reviews in Plant Sciences 22 (5), 471-502. Doi: 10.1080/07352680390253179
Luthi, D., LeFloch, M., Bereiter, B., Blunier, T., Barnola, J., Siegenthaler, U., Raynaud, D., Jouzel, J., Fischer, H., Kawamura, K., & Stocker, T. F. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 453, 379-382. doi:10.1038/nature06949
Montgomery, D. (2019, Aug 13). Restoring soil can help address climate change. Retrieved from
Montgomery, D. (2017, April 14). It's time to make soil great again. Retrieved from
Noulas, C., Tziouvalekas, M., & Karyotis, T. (2018). Zinc in soils, water and food crops. Journal of Trace Elements in Medicine and Biology 49, 252-260.
Welch, C. (2017, June 14). Climate change pushing tropical diseases toward Arctic. Retrieved from
