So beef burps are now officially vindicated as a (“the”!) leading cause of climate change. The reason is pretty embarrassing: The way we converted the warming potential of methane into “CO2 equivalents” based on the 100-year warming potential is in itself correct but cannot be utilized for “flow variables” like methane.
Methane remains in the atmosphere for about 10 years, until it is oxidized (mostly by hydroxyl radicals, OH). With a relatively constant herd size, the atmospheric methane contribution of ruminant remains constant. With every new burp, an old burp is oxidized in the atmosphere. Somehow, the climate activists missed that when doing their greenhouse gas accounting! Instead, methane emissions are mostly coupled to overall livestock numbers, to production practices and varieties/breeds, and eventually to the biogenic hydroxyl radical cycle that is only partly understood.
Historic ruminant populations are also contested. Likely, North America had more ruminants during the 15th century or even during the Pleistocene, as compared with today. But populations in other countries are heavily contested and not adequately researched. With modern ruminant populations nearing 2 billion, many sources claim that the total abundance has also increased. Others point at dramatic capacities of grasslands to sustain ruminants; populations may have matched today’s numbers. More research is needed here! If modern numbers exceed historic ones, this will cause an increased Methane account.
The focus on Methane has hit the entire beef industry sector negatively – both regenerative grazers and industrial feedlot producers. This was in part due to over-simplistic calculations and is indicative for how prone our “mechanistic mind” is to such types of mistakes. Like most people, I never fully bought the Methane-by-ruminants story but did not catch the potential error. We all must start looking at systems, flows, stocks, buffers. We need to respect complexity and local context – we must start managing complex systems. To me, this is humankind’s challenge of the 21st century.
CAUTION! This methane error does not vindicate the massive GHG impact of meat consumption. It just reduces the relevance of methane burps, which were used to single out cows as the culprids of climate change. Industrial production of feedlot meat, based on monocultures of feed crops that destroy biodiversity, degrade soil and release soil carbon continues as before. However, it shifts the culprit a bit – from red meat to (1) feedlot meat in general for a myriad of reasons, (2) the dominant poor ruminants grazing practices that lead to soil-degradation, (3) monogastrics (pigs and chicken) that heavily rely on grain feed, (4) negative impacts on the water cycle and the biosphere’s self-regulating functions. It’s not the cow, it’s the how.
https://www.quantamagazine.org/forests-emerge-as-a-major-overlooked-climate-factor-20181009/
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