Agriculture and The Environment
Alan Hahn, Environmental Scientist at Dragun Corporation Environmental Advisors
Agriculture and The Environment


As we go through our daily lives, individually and collectively, we leave a “footprint on the environment.”


As our population has grown, so has our collective environmental footprint.  When we numbered about 1 million humans around 1000 BC, our footprint was relatively small and localized.


Today our population is somewhere around 7.8 billion and expected to continue to grow to 10 to 11 billion by the end of the century, when the population will begin to fall. 


Regulating, measuring, and limiting our environmental footprint is relatively new. In the United States, the Environmental Protection Agency wasn’t established until 1970. Up until then, there were a smattering of laws concerning the environment including the Rivers and Harbors Act (1870), Oil Pollution Control Act (1925), and the Federal Water Pollution Control Act (1948).


Protecting our environment is essential for future generations. Protecting the environment requires that we have scientific facts before offering solutions.  Unfortunately, hyperbole often muddies the waters.


When it comes to atmospheric science and understanding how we are influencing the climate, it is often the hyperbole that is ahead of the science. In recent years, there has been a lot of misinformation about how agriculture may be affecting the climate.


Greenhouse Gases

Much of the environmental concern related to agriculture has focused on man-made (or anthropogenic) Greenhouse Gases (GHGs). One of the early, detailed looks at GHGs from agriculture was from the United Nations Food and Agriculture Organization (FAO).  The 2006 report, “Livestock’s Long Shadow” set the tone for debate and more detailed studies on agriculture’s emissions.



The FAO concluded in their extensive study that globally, livestock was responsible for 18% of all the GHGs. This meant that livestock is responsible for more GHG emissions than all of transportation combined. Logically, this does not make sense. As it turns out, there was an error in methodology. When calculating livestock emissions, they used a life-cycle assessment (basically taking every input into consideration from field to fork). When evaluating transportation, they looked only at tailpipe emission. This inconsistency is a glaring error when comparing the resulting GHG emissions. There were some environmental groups that used this report to call for greater controls on agriculture. To be fair, FAO owned up to their mistake.


The Science

The GHGs associated with agriculture are primarily nitrous oxide and methane (from ruminant animals). It is primarily methane that gets the attention, as methane’s global warming potential (GWP/100 years) is 24 times greater than carbon dioxide. 


However, while methane is a more potent GHG, it remains in the atmosphere only 20 years. Carbon dioxide stays in the atmosphere for another 80 years. Accordingly, the climate impact from livestock is relatively short-term and doesn’t accumulate over near the same duration as the impact from fossil fuels.


Further, farming’s impact on the environment in the United States is very different than it is in developing nations that have not adopted modern farming practices.


Latest Research

Thanks in large part to Frank Mitloehner, Ph.D. Professor, Department of Animal Science University of California, Davis, we are learning much more about the true global warming footprint from US Farms.


Dr. Mitloehner in his testimony before the Committee on Agriculture, Nutrition, and Forestry (U.S. Senate) said among other things, “In the United States, we rely heavily on the Environmental Protection Agency (EPA) to supply us with GHG data. Based on EPA’s 2016 report, the following sectors/activities contribute to GHGs accordingly: transportation – 28%, energy – 28%, industry – 22% and agriculture – 9%. The agricultural figure includes animal agriculture at 3.9%.”


Better Productivity = Smaller Footprint

Again from Dr. Mitloehner’s testimony, “According to the United Nations Food and Agriculture’s statistical database, total direct greenhouse gas emissions from U.S. livestock have declined 11.3% since 1961, while livestock production has more than doubled.” 


He points out later in his testimony, “in 1950, there were 25 million dairy cows in the United States. There are 9 million presently, but today’s herd produces 60% more milk than their ancestors did.” Mitloehner says that means over this time, the carbon footprint of a glass of milk has been reduced by two thirds.


Dr. Mitloener credits these gains to efficiencies in reproduction; better health, brought about in part by vaccinations and advances in health care; the application of “high-merit” genetics; and more energy-dense diets. Other countries (developing countries) that have not shared in these advances do not show the same reductions in emissions. 


In a study by Jude Capper and Roger Cady, they found that compared to 2007, producing a gallon of milk in 2017 required almost a quarter less land, 30% less water, along with a 19% reduction in our carbon footprint. (Journal of Animal Science, Volume 98, Issue 1, January 2020).


Food Waste and Consumer’s Role

Another factor in GHGs associated with agriculture is food waste. Few people consider how our daily lives, including wasted food, influences the environment. The United States Department of Agriculture estimates that 30-40% of our food is wasted. Much of this is at the retail and consumer level. Some retailers are offering incentives to buy “ugly food.” This fruit may be perfectly fine, but for a few bruises. Our World in Data estimates that 6% of the GHGs come from food loss and waste.


Concluding Thoughts

Agriculture has developed or is participating in many different environmental stewardship programs. Research is ongoing at many levels to find ways for agriculture to be more sustainable. Universities are now offering degrees in agriculture sustainability programs. Many states, including Michigan and Wisconsin, have voluntary stewardship programs.  


Both agricultural science and atmospheric science are complex and nuanced. The intersection of these sciences is a relatively new study. As we learn more, we will find greater efficiencies to meet the demands that lie ahead in the coming decades. These advances have been and will remain possible as we continue to embrace on the scientific understanding of our many environmental challenges.


To view the article in the online 2021 Fall Partners Magazine, click here.


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