PUBLISHED BY MANITOBA BEEF PRODUCERS
MARCH 2021
PHOTO CREDIT: JONATHAN ROFFEL
At the conclusion of the virtual 42nd AGM, several of the new and returning faces on the MBP Board of Directors posed for a photo. See story on page 4 of this issue.
Rethinking methane Many livestock producers have suffered unfair blame when it comes to their environmental footprint, but Dr. Frank Mitloehner of UC Davis is determined to change that. At the Manitoba Beef Producers Annual General Meeting in February, Mitloehner explained how he, and other researchers, are changing the narrative on greenhouse gas (GHG) emissions from the beef and dairy sector, to one where producers are viewed as an asset in the fight against global warming, rather than a liability. The narrative begins with dispelling the myths and highlighting the facts around methane production from cattle. Methane is very different from CO₂ The fact is that cattle production does produce GHG emissions of carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄), but it’s important to understand that these gases operate very differently in the atmosphere. CO₂ and N₂O both persist for a long time in the atmosphere (up to 1,000 years), but methane is destroyed by a process called hydroxyl oxidization within 12 years. To relate the importance of this for cattle production, it’s necessary to understand the Biogenic Carbon cycle by which methane from livestock is produced and destroyed. The Biogenic Carbon cycle (see link at end of article) begins with photosynthesis, where plants convert sunlight, water and carbon from the atmosphere into carbohydrates, such as cellulose or starch. A bovine eats this material, digests it through a process called enteric fermentation, and expels methane in its waste products. Carbon in the meth-
ane is converted, through hydroxyl oxidation, back into CO₂ which goes back into the atmosphere, but that carbon is recycled carbon, identical to the carbon that was in the atmosphere in the form of CO₂ that the original plants photosynthesized to begin the cycle. “As long as herd sizes are stable, the amount of methane produced by your cattle, and the amount of methane destroyed by hydroxyl oxidation will be in balance,” Mitloehner said. “Constant cattle herds do not add additional carbon or methane to the atmosphere, and they do not cause additional warming to our climate.” Carbon derived from fossil fuels (oil, gas, coal) is different because it’s a one-way process, said Mitloehner. “Fossil fuels were formed from decayed plant material that fossilized and accumulated in the ground over a very long period of time,” he said. “Over the last 70 years, we have extracted about half of that ancient carbon, and burned it in our cars, planes, trains, ships, power plants and so on. We put that carbon into the atmosphere mainly in the form of CO₂ and why we see CO₂ levels rising year after year, is because it’s not a short time cycle, but a very long, one-way street of fossil carbon from the ground into the atmosphere.” Why animal agriculture gets a bad rap The reason why animal agriculture has been vilified in terms of the impacts of methane on the climate has largely been due to a matrix called the GWP100, used for the past 30 years to calculate global warming potential of different GHGs. Generally, using this formula, methane (and N₂O) emissions are converted into CO₂e (equivalents) and, in the case of methane, is multiplied by a factor of 28. So, a ranch producing 100 tonnes of methane, is producing 2,800 tonnes of CO₂e.
This system is wrong, Mitloehner said, because it does not take into account that methane is both produced and destroyed, and is not cumulative in the atmosphere over a long period of time as CO₂ and N₂O are. Scientists have developed a new matrix, called the GWP* (see link at end of article) that does account for this difference, and gives a more accurate picture of methane’s climate impact. Scientists compared three scenarios, increasing methane by 35 per cent over 30 years, maintaining the same amount of methane emissions over 30 years, and decreasing methane emissions by 35 per cent over 30 years, using both the GWP100 and GWP*. The GWP100 predicts strong increases in CO₂e, translating into increased global warming, with all three scenarios, while the GWP* predicts that increasing methane by 35 per cent would indeed increase warming, but maintaining a stable level of methane would result in a slight decrease (around 10 per cent) in warming, and a reduction of 35 per cent of methane emissions would result in cooling. Applied in the context of animal agriculture, the key message is that stable herds or flocks will not add to global warming, and that, in fact, if methane emissions from livestock production can be decreased, it will help to reduce global warming. So, it Page 2 POSTMASTER: PLEASE RETURN UNDELIVERABLE COPIES TO: MBP, UNIT 220, 530 CENTURY STREET, WINNIPEG, MB R3H 0Y4 CANADIAN PUBLICATIONS MAIL PRODUCT SALES AGREEMENT NUMBER 40005187 POSTAGE PAID IN WINNIPEG.
BY: ANGELA LOVELL
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