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Methane emissions: don’t blame cows and camels, blame the oceans

Steak-lovers — look at the volatility in the graph of methane levels. That is not the cows…

Methane emissions are a bit of a sleeper. They are ignored (even by me) yet and cows, sheep, pigs and lamas produce a whopping 11% of the Australian national greenhouse emissions (mostly as methane and nitrous oxide). Livestock emissions are 70% of our entire agricultural sector emissions. They are so important, at one stage Australia was considering a camel genocide — hoping to stop storms and reduce droughts by knocking off some camels. So if we like ham, steak and hamburgers, we need to pay attention. The carbon-politisi are coming.

The UN thinks we need to worry about methane which has 34 times the impact of CO2 (which is 34 times something immeasurably insignificant, so who cares?). Somehow global methane levels are often blamed on fossil fuels and farting cows, but this latest analysis suggests humans are pretty much irrelevant.

Tom Quirk tracks the annual changes in methane and finds that it bumps up by both big and small amounts, and the volatile pattern doesn’t match human agriculture or mining but rises and falls in time with El Ninos. This is not entirely surprising as El Nino’s affect rainfall (and thus affect droughts and fires). And wetlands are the largest natural source of methane on Earth. Dryness leads to methane…

Humans were once responsible for the global rise in methane, as Tom Quirk explained in 2013. Russian pipes were so leaky in the 1970s and 80s that the large annual increases in methane may have been due to “communist maintenance”. When the Soviet Union started selling natural gas to the Europeans, the leaks were stopped and the rises in methane became much smaller.

It’s another wonderful bit of original research from Tom Quirk. Looks like thousands of cows and camels may be saved.

— Jo


Guest post by Tom Quirk

Latest Methane Measurements from Cape Grim

Annual changes in atmospheric methane show no smooth progression but rather great variability.

The annual changes in direct atmospheric methane measurements from 1986 to 2018 are shown in Figure 1 along with 12 year smoothed ice core data from 1900 to 1991. These measurements are from the CSIRO at Cape Grim and ice cores at the Law Dome in Antarctica.

Methane, Global, graph, 2019

Figure 1: Annual changes in atmospheric methane in ppb per year from ice cores at the Law Dome in Antarctica with 12 year smoothing and direct annual measurements at Cape Grim in Tasmania

Law Dome measurements.

The Law Dome ice core measurements show rising annual emissions in the last half of the twentieth century. This is understood to be due to leaky gas pipelines and in particular the Trans-Siberian pipeline[1] where the leakage was much reduced in the 1980s. There is also a gentle rise to a peak in the mid 1920s and then a gentle decline. The decline is at the start of the Great Depression with a recovery at the start of the Second World War. Figure 2 shows a similar rise and fall from an estimate of total fossil fuel emission for the United States[2] so the Law Dome data may reflect the economic events of the early twentieth century. Similarly the change in trend in the early 1970s may reflect the economic recession that followed the oil embargo of the Arab-Israeli war.


Methane, Global, graph, 2019

Figure 2: Annual and10 year running average of total fossil fuel emissions for the United States from CDIAC estimates. Note the peak in the mid 1920s.


Cape Grim direct measurements

The direct annual measurements at Cape Grim in Tasmania are also shown in Figure 3-upper along with the year of the Mount Pinatubo eruption, 1991, and the years in which El Ninos occurred. Figure 3-lower shows the monthly El Nino 3.4 Index.

The Pinatubo eruption coincides with an atmospheric methane peak. This has been explained[3] by the sulphur dioxide from the eruption reducing the removal of methane from the atmosphere.

The remaining methane peaks coincide with the years in which El Nino’s occur. There is one exception in 2016 where the methane peaks in 2014, preceding the El Nino peak by 2 years.

The methane peaks are associated with droughts and forest fires from changing conditions in wetlands[4].  Also there were massive forest fires in 2014 and 2015[5].


Methane, Global, graph, 2019

Fig 3a

Methane, Global, graph, 2019

Fig 3b.


Figure 3a: (upper) : Annual changes in atmospheric methane in ppb per year from ice cores at the Law Dome in Antarctica with 12 year smoothing and direct annual measurements at Cape Grim in Tasmania. The vertical red line is for 1991, the year of the Mount Pinatubo eruption and the vertical black lines are the years for El Ninos .Fig 3b (lower) Monthly El Nino 3.4 Index.


The main source of atmospheric methane since 1995 is from natural sources with great variability.

It is not from domestic livestock as noted by Albrecht Glatzle[6]. However it is possible fracking and increased transport of natural gas may make a contribution to the methane in the atmosphere.


Export Table, Morgan, Australia, Iron, gold, tourism, education, oil, agriculture.


[1]   Tom Quirk  ENERGY & ENVIRONMENT Vol 21 p 251-266, 2010
[2]   CDIAC data https://cdiac.ess-dive.lbl.gov/trends/emis/tre_coun.html
[3]   S. Bekki, K. S. Law & J. A. Pyle “Effect of ozone depletion on atmospheric CH4 and CO concentrations” Nature 371, 595-597 (13 October 1994) | doi:10.1038/371595a0
[4]   Bradfield Lyon. “The strength of El Nino and the spatial extent of tropical drought”  Geophysical Research Letters, Vol 31, L21204, doi:10.1029/2004GL020901, 2004
[5]  Drought and heat exacerbate wildfires  https://public.wmo.int/en/media/news/drought-and-heat-exacerbate-wildfires
[6]   Albrecht Glatzle :Domestic Livestock and its Alleged Role in Climate Change,
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