Grasping the relative size and importance of very small fractions can be challenging. Discussing parts per million or percentages with several zeros can become meaningless. Sometimes analogies are helpful.
An example is trying to gather the size of methane in the atmosphere or just the amount of ruminant methane that, latterly, has been receiving a bad press from green groups desperate for new villains.
All methane in the atmosphere is 0.00018% or less than two parts per million. What does that look like in terms that are relatable?
Imagine the whole of the atmosphere is a car trip from Los Angeles to New York or 2,778 miles. That is 4,471 kilometers if you prefer metrics. All the planet’s methane would be just the first 26 feet from the starting point. That is approximately 8.5 metres. It is a very minor amount by any reckoning.
A portion of these methane emissions is natural but a little over half is supposedly anthropogenic. There are several sources of the anthropogenic emissions including biogenic emissions from ruminants. They make up approximately 15% of all methane emissions. Some of these numbers have rather large variability with +/- factors of up to 50% so care should be taken quoting them.
Using the road trip analogy ruminants from around the planet relate to a mere 4 feet in the LA to NY journey or about 1.3 metres. With the USA home to 10% of the world’s ruminants they would constitute a miniscule 5 inches (13 centimetres) out of the 2,778 miles.
In my home country, New Zealand where agriculture is the major feature of the economy and is erroneously claimed to be producing 48% of the nation’s greenhouse gas our ruminant emissions would equate to half an inch on the LA to NY trip.
The simple point is that those opposing meat production, vegans, vegetarians, anti-farming voices along with climate catastrophists who are so vociferous about farming doing its bit for saving the planet need to apply some rational thinking to how 5/176,000,000 could impact anything no matter how much they want to try and magnify the methane molecule’s potency.
Even more telling is that methane is thoroughly overshadowed on the electromagnetic spectrum where water vapour, particularly and CO2 reduce its radiative forcing capacity dramatically. Methane absorbs on a narrow band in the 7 to 8 micron range at less than 50%.
By contrast water vapour absorbs over a very broad region of the spectrum.
There is one other important issue relevant to ruminant methane. The vegetation (mainly grass) eaten by ruminants relies on the natural carbon cycle where photosynthesis converts CO2 from the atmosphere into plant material. When eaten this green matter produces methane emitted into the atmosphere where it oxidises into CO2 and water vapour needed, in turn, to grow the grass.
With methane lasting less than 12 years in the atmosphere a stable ruminant population is not contributing any additional greenhouse gas or any additional warming. Ruminant numbers in the USA have been declining for over 20 years which means American farmers should be commended by the climate change extremists for actually contributing to slight cooling.
A similar situation is occurring in New Zealand where ruminant methane levels have stabilised and are trending downward. However the Government remains resolutely wedded to taxing farmers at levels that will impact farm decision making. Ideology and bloated pay checks rules.