Submitted to Rural News
In a 1 August opinion article (Could the paradigm be shifting? (ruralnewsgroup.co.nz), Doug Edmeades reports on a seminar given by American physicist Tom Sheahen, who argues that the climate effect of the greenhouse gas methane is so small as to be irrelevant. It would be so easy if this were true, but, unfortunately, it isn’t. But I agree with Doug; a paradigm shift is under way, nonetheless.
Sheahen quotes work by two climate scientists: William van Wijngaarden and William Happer. They’ve published a number of articles together and with others in peer-reviewed scientific journals. Their specialities are the optical properties of the atmosphere and computer modelling of those properties. The content of their peer-reviewed publications generally conforms with mainstream climate science.
The article referenced by Sheahen is an un-peer-reviewed article titled “Methane and Climate” published in 2019 by an organisation called the CO2 Coalition. Their stated purpose: “The CO2 Coalition of climate scientists and energy economists informs the public (1) about the net beneficial impact of carbon dioxide emissions on the atmosphere, land and oceans, and (2) the net negative impact on the economy, living standards and life expectancy of reducing these emissions by restricting access to energy”. It is clear that this group has a scientific bias.
The article claims that the present rate of warming by molecular methane is only 10% of that of molecular carbon dioxide, so why worry about it? This is the gist of Sheahen’s argument about methane.
The fact that this article is not peer-reviewed is worrisome. Science is based upon repeatable experimentation and collective agreement. Work that does not have the stamp of approval from other scientists is not yet considered valid. This peer review process is in place to prevent fraud and it generally works pretty well. The history of science is full of examples where peer-review was not allowed to confirm important results, usually due to political interference, and whole disciplines of science have been led astray. Look up “Trofim Lysenko” for a good example of this.
While van Wijngaarden and Happer’s conclusion about methane may be correct, there is no way to confirm it without peer review. I found one review; a 2019 E&E News article by Scott Waldman, reprinted in Science magazine. The article states, “The paper's claims largely have been known since the 1960s, said Andrew Dessler, a climate scientist at Texas A&M University who reviewed the research. He said the calculations appeared to be correct, but that they were presented in a misleading way.”
So, how are they misleading? One obvious way is the omission of any mention of methane’s chemical interactions in the atmosphere, leading to tropospheric (lower atmosphere) ozone production and increased stratospheric water vapour – both intense greenhouse gases. This increases its warming effect.
In addition, the near tripling of methane concentration in the atmosphere since pre-industrial times (729 parts per billion (ppb) in 1750 to 1866 ppb in 2019) has led to it accounting for 25% of the effective radiative forcing (warming) of carbon dioxide (IPCC AR6 WG1 2021, page 960). In a second opinion, the International Energy Agency has concluded that methane accounts for 30% of global warming to date (Global Methane Tracker 2022, IEA, Paris).
But, let’s go back to the original claim; that methane’s contribution to global warming is too small to worry about. We need to consider the size of the global warming problem and the fairness in how we address it. The problem is huge and requires all hands to the pump. We don’t excuse Joe from helping because he is only one-tenth of the workforce. In terms of fairness, New Zealand businesses and councils face the higher cost of carbon dioxide and landfill methane emissions through the emissions trading scheme, so why should farming get a pass?
I agree with Mr. Edmeades’s suggestion that the paradigm is shifting, however. While we’ve long seen government concern for farming’s greenhouse gases, we are now beginning to see similar concern from large overseas industry buyers. The food giant Nestle is leaning on Fonterra to lower the emissions on its milk products. The European Union is talking about applying “border adjustment mechanisms” (i.e., carbon tariffs) on importers who do not take steps to limit their greenhouse emissions.
The paradigm is changing. Reducing greenhouse gas emissions isn’t just good for the planet, it is now becoming good for business too.
Tom Powell is a retired geoscientist who writes on climate matters for the Marlborough Express.
These are a collection of opinion articles principally written by CKM member Tom Powell for the Marlborough Express. Tom is a retired geologist who came to New Zealand in 2004 to work in the geothermal industry on the North Island, is a New Zealand citizen and now lives in Blenheim. Some articles have been written by other CKM members, and their names appear with those articles.