Should farmers be worried about the COP “Methane Pledge” to reduce methane emissions by 30% before 2030?^[1] There was real concern amongst them in the UK and Ireland, especially when newspaper headlines advertised that Ireland might need to cull 1.3 million head to reach its climate goal. It certainly raises a number of problems. Methane is one of the most seriously misunderstood of GHGs; listening to popular discussions one would think the problem was rooted in livestock, and would be solved by having the world go vegan; neither is true.

First some basics: methane is a potent greenhouse gas, and is supposed to have contributed roughly 30% of the global warming of the past two centuries. Importantly, it does not last long in the atmosphere, and so does not accumulate; within a decade a molecule of methane is likely to have reacted with oxygen in the atmosphere to leave carbon dioxide and water. Next, methane is generated naturally when organic matter decays; the wetlands we try to preserve are a major source, marsh gas is largely methane. The thawing of permafrost with warming in the high arctic is another natural source; the International Energy Agency estimates that 40% of methane emission are in fact absolutely natural.

Of the 60% for which society is responsible, nearly a fifth comes from city dumps and waste treatment. Another third comes from the coal, oil and gas sectors; it is a major component of fire-damp in coal mines, and of natural gas. And, yes, it does come from the guts of herbivores, whether ruminants or hind-gut digesters. These are not just cows and sheep, but also wild herbivores from termites to bison and elephants. The last millennium has seen a major change in the proportion of large herbivores that are domesticated, but I’ve yet to see any comment on their total biomass over time. Whether wild or domesticated, they are part of the natural carbon cycle. Plants are eaten, animals exhale carbon dioxide and their guts yield methane, and as levels of CO2 rise, plants grow faster, locking in more carbon, until it is again released. That said, recent research has shown that stock farmers can achieve substantial declines in enteric methane after adding dry seaweeds to feed.    

The attention of the world has focussed on the livestock sector; despite the leaks from coal mines and gas and oil fields being the real source of change in atmospheric methane in recent centuries.

So what is one to make of the COP26 “methane pledge” to cut methane emissions by 30%? First, while 105 countries, including the USA, Saudi Arabia and EU nations, signed it, some important countries didn’t: China, India, Russia and Australia – all major producers and users of coal and gas, are amongst the missing. Second, some of the signatories do seem to have given it serious thought. The USA, for example, has detailed the mechanisms it will follow, including an EPA proposal that will require oil and gas operators to monitor 300,000 of their biggest well sites every three months, stop methane venting, and try to detect and repair methane leaks.

Importantly, agriculture is a distant 5th in the USA’s list of methane cutting activities. Hopefully the rest of the world will take note and shift some of the methane focus away from stock farmers.

^[1] https://www.globalmethanepledge.org/