Written by: Lorie Smith, Georgian Central Regional Communication Coordinator

Discussions about global warming and greenhouse gases (carbon dioxide, methane, and nitrous oxide), and the casting of blame on various contributors is taking place in boardrooms across the planet. The determination about an industry’s contribution to global warming is dependent on the approach used to determine the Global Warming Potential (GWP 100 model and GWP), the interpretation of said results (Life Cycle Assessment [LCA] vs linear carbon footprint), and carbon accounting.

Christoph Wand

 Christoph Wand

Many livestock producers feel barraged with negative publicity about their contribution towards Greenhouse Gas emissions (GHG), primarily in the form of methane. Christoph Wand, Livestock Sustainability Specialist, and nutritionist with OMAFRA, confirms that livestock contribute to global warming, but the “sky is not falling” as some would have us believe. He observes that the current GWP 100 model of assessment unfairly penalizes short-lived emissions like “biological” methane, so the cattle industry advocates for the GWP metric. They also use an LCA of carbon emissions, which considers more impact categories and inputs. Importantly, an LCA of the beef industry, including the feed, fuel, and electricity used, conducted by the Canadian Roundtable for Sustainable Beef (CRSB) in 2016, showed that emissions from cattle production contributes to only 2.4% of our total emissions. It should also be noted that while methane is more potent than carbon dioxide, The Global Carbon Project (http://www.globalcarbonatlas.org/en/CH4-emissions) estimates that of the 558 million tonnes of methane produced globally each year, 98% of it is broken down and reabsorbed by plants and soils, known as the sink effect.

As per the info-graphic, livestock’s greenhouse gas footprint comes from a variety of sources. One of the by-products of bacterial breakdown of fiber in the rumen is methane (enteric fermentation). It is expelled as cattle belch, with beef and dairy cattle accounting for the largest share of livestock emissions. The cow-calf sector accounts for more of the methane emissions than the other stages of the value chain, as they feed more forages. The volume of methane emissions is a function of the cow’s diet (feed type and quality), and the breed/genetics. Additionally, greenhouse gases are emitted from manure storage which produces methane and nitrous oxide during the anaerobic decomposition of the organic matter. Of note, nitrous oxide has a much higher GWP than either methane or carbon dioxide. Enteric fermentation and emissions from manure contribute about half of the total carbon footprint attributed to livestock. Importantly, feed production and energy consumption account for the remainder.

To remove some of the noted elements of the livestock greenhouse gas footprint, one needs to de-carbonize agriculture. To reduce the methane produced when a cow belches, farmers need to modify and better manage the cows diet. There are complex ways of doing this with current research exploring the use of feed additives (natural substances, fats, oils, seaweed, ionophores and probiotics), and selective breeding (identifying the markers associated with low methane production). The same end goal could be achieved with existing low-tech solutions. Wand comments that “Farmers should improve their forage digestibility, which is in part, dependent on the choice of cutting date.” The poorer the quality/more mature the forage, the higher the methane production. A report from the 2021 Cattlemen’s College stated that a four percent increase in digestibility could lead to reduced methane emissions. If farmers feed less forages to ants, they produce less methane, but Wand challenges us to look at the overall carbon footprint impact of those forages, instead of looking to get the lowest number out of the animal. Productivity also improves our carbon footprint. “Some of those simple choices—keeping animals alive, timely animal health intervention, and genetic choices, improve productivity to offset the cow herd’s climate change impact,” states Wand. Finally, methane emissions from manure can be managed by using various technologies. These include covered lagoons, digesters, aeration manure, filtering, and composting.

In terms of the emissions from transportation, and farm practices/food production, “If the infrastructure continues to be set up for fossil fuels, we are not sustainable, and there are leaks in the loop,” stresses Wand. He emphasizes that is why the questions around land use, success in crop production (nitrogen usage, tillage, diesel versus electric, large versus small implements, automated seeding/weeding machines, heat drying grain) and GHG reduction become very important in reducing the feed/livestock footprint.

Cattle grazing on cover crop pasture, fall 2021

Photo credit: Kara Sickle. Cattle grazing on cover crop pasture, fall 2021

If farmers are grazing animals properly and sequestering carbon in their crops, there should be a closed loop carbon system, and therefore net zero emissions would be achieved. Agriculture is part of the nature-based solution for climate change, but when pastureland is plowed up, or forests are cut down and turned into other crops, that sequestered carbon is lost. Thus, land use management will be key to meeting climate change targets.

Moving forward to reduce emissions from agricultural practices, farmers will need to produce food even more efficiently. This may mean that farmers will need to change how they farm. Will farmers be ready to make those changes?

2 Responses

  1. Reply
    Rob Campbell
    Nov 20, 2021 - 07:13 AM

    First, the issue is not that 98% is absorbed, but that methane is absorbed in ten years whereas CO2 persists for centuries: see https://www.oxfordmartin.ox.ac.uk/downloads/reports/Climate-metrics-for-ruminant-livestock.pdf . Politicians and corporations are looking at reducing emissions but, as the linked article shows, the experts stopped focussing on that and started focussing on greenhouse warming potential (generally denoted GWP*) as opposed to GWP 100 back at COP28.

    Second, the author looks at all contributors to livestock production, which is appropriate and admirable, but climate change is a systems problem and thus will only be solved by systems solutions. Finally people are seriously considering their impact on climate change but any attempt to solve the root problem has to consider all twelve metrics of planetary carrying capacity, including biodiversity loss, nitrogen & phosphorus loading, and chemical pollution. Focussing just on climate change leads to “solutions” that will do more harm than good (or are massively risky), like geo-engineering and the never-ending arms race of solving problems with pesticides.

    Consider perennial pastures’ vastly superior contribution to water cycling, soil biome health, carbon sequestration, biodiversity, and reduced inputs (all of which are enabled by properly grazing ruminants) versus annual crops. As a bundle of goods and ecological services it is a high bar for feedlots, grazing annuals, or strict vegan food production to match, especially when so much agricultural land requires so many more external inputs to grow annual crops versus perennial pasture.

    Finally the article concludes that we “…need to produce food even more efficiently”. Realize that the author is talking about a very different KIND OF efficiency versus how the work is usually used in agriculture. Efficiency is the ratio of outputs to inputs; we decide which outputs and inputs are important. The ag industry has had us focussing on bushels per acre, which has led to the most energy-inefficient production system the world has ever seen, using 2.9 calories of fossil fuels for every calorie of food on grocery store shelves ( https://www.overshootday.org/food-and-fossil-fuels/ ). “Efficiency” will need to measure food value (not just calories of energy) over the environmental cost of growing it (not just fossil fuel use or GWP*), offset for environmental benefits of the way it is grown. It is a sea change in how we look at what we do.

    • Reply
      Lorie Smith
      Nov 20, 2021 - 12:12 PM

      Thanks so much for your great comments Rob! As with many topics, you have a vast understanding of this one, and your points are well taken. This topic is definitely broad, and everyone has many points to add to the discussion. In the article I was relaying one person’s accounts during our interview. Thankyou for your builds and clarifications.

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