Professor Peer Ederer addressing the 2025 WagyuEdge Conference in Perth.

Despite similar amounts of biological sources of methane existing pre-industry, today’s levels in the atmosphere are vastly higher—challenging assumptions about emission dynamics and atmospheric lifetimes.

The quandaries raise the possibility that the main driver of higher methane concentrations in the atmosphere was not increasing emissions but rather a change in what destroys methane in the atmosphere.

A recently published article in the April 2025 edition of Animal Frontiers Journal highlights some major methane questions that are yet to be answered by science.

After remaining comparatively stable for 800,000 years, methane levels in the atmosphere have increased by almost three times in the past 150 years.

That issue has alarmed many countries, with 158 nations in 2021 signing a Global Methane Pledge to reduce global methane emissions at least by 30 percent from 2020 levels by 2030.

Yet the question of why that rapid methane buildup in the atmosphere has occurred has not yet been properly answered or satisfactorily explained, according to the Animal Frontiers Journal article authored by Peer Ederer and Taras Iliushyk from the Global Observatory for Accurate Livestock Sciences, Switzerland.

Current modelling is also yet to satisfactorily explain why the rise of atmospheric methane concentrations slowed since the mid-1980s, and then paused for six years between 2000 and 2006 (as per blue line below), before resuming towards a record speed of increase, without any indication that methane emissions increased correspondingly.

Image source: Animal Frontiers Journal April 2025

A regime change in methane emissions has clearly occurred in recent times, for which a convincing explanation is still outstanding, the authors state.

Expanding on this, they write that between the years 1900 and 2002, the isotope C13 fractionation values continued to go up, meaning the atmospheric methane mix became heavier with relatively higher portions of the isotope C13.

However, since 2002, the fractionation values have been dropping rapidly (as depicted at the right of the below chart).

Image source: Animal Frontiers Journal April 2025

“The background is that different emission sources and different destruction mechanisms of methane have different fractionation ratios, and therefore a change in the trend indicates that the composition of the sources over the past 20 years is much different from that of the previous 100 years, or the pattern of destruction is different, or both,” the article states.

Overlooked 7-year cycle raises geological link to methane concentrations

The report also identifies a largely overlooked and unresearched  “7 year cycle” of rising methane concentrations in the atmosphere.

It notes that the 7-year cycle can be clearly discerned in ice-core data reaching back to the 1850s, with indications it also existed for the past 500 years as well.

“Since there is no global meteorological phenomenon which exhibits such regularity, there must be a geological impulse which impacts the atmospheric methane concentrations.”

“Finding and explaining this geological impulse could also trigger a different paradigmatic understanding.”

The almost three-fold rise in atmospheric methane concentrations in the past 150 years is typically explained as having been caused by substantially higher human-caused emissions.

“However, that is not that clear,” they write.

“Then [in paleolithic times] as now, the majority of methane emissions were of biological origin. Then as now, there were a comparable number of methane-emitting ruminants deployed on global grass- lands (Smith et al., 2016).”

Wetlands, rainforests and surplus non-eaten biomass should have been emitting substantially more methane compared to today, because of their much larger extent.

“Then as now, geological emissions were tiny, at less than 5% of the total.

“The only real difference are the 20% anthropogenic fossil fuel methane emissions of today that did not exist before industrial times, but it is quite possible that they were compensated by the larger extent of wetlands and rain forests.

Global methane emissions for paleolithic times are generally assumed to be much lower than today, but that is only because the atmospheric models assume that methane lifetime is more or less fixed at currently observed levels—”an assumption that is neither well proven nor plausible”, the authors write.

“Roughly speaking, if atmospheric lifetimes were assumed to be one-third of today in paleolithic times, then the same amount of emissions of today in those times would lead to the one-third of concentrations during the paleolithic which we are observing.”

“But then the research question would be an entirely different one to today. Researchers would then have to ask why lifetimes were so much different versus today, rather than whether or why emissions are higher.”

Additionally the dramatic Young Dryas event 12,800 years ago, when in a few decades North America and Europe were plunged into a 1200 year ice age, which then disappeared as fast it came, also raises questions about methane phenomena at the time that are still yet to be answered.

The paper documents many shortfalls with the current assortment of atmospheric methane modelling in use, such as the lack of definitive information on the many open variables at play, wildly fluctuating estimates, the lack of computing power to manage the complexity and sophistication required while still not taking into account the full spectrum of variability of dynamic micro-effects, leading to confidence intervals for outcomes that tend to be broader than the rate of annual increases of the methane reservoir.

The paper proposes viewing the methane cycle as a non-linear system (NLS)—capable of shifting between equilibria and reacting disproportionately to small changes.

It is also possible that increasing methane emissions are not the driver for increasing concentrations – but rather a change in what destroys methane in the atmosphere.

“These models cannot disprove that the same effect may come about if less methane were to be destroyed in the tropics, instead of more being emitted.”

“This would then raise the question of why less might be destroyed, for which there is also no answer yet.”