OWEN JENNINGS: Radio Spectra and Methane

I am old enough to remember getting out of bed at 3.00am on cold mornings to listen to the radio broadcast by Winston McCarthy of the All Blacks playing in South Africa. No TV’s back then. McCarthy’s inimitable voice captured not just the passage of play but managed to lift excitement levels several notches even in dull games.

Our radio – a Gulbranson – was a walnut, wooden box with a fabric covered speaker and a dial – the short and medium wavelength – where one searched for stations. Dad had fixed a long rod onto the knob that selected the stations so he could make minor adjustments to get a clear message. We had to get the precise wavelength to get the commentary. Any other wavelength was ineffective.

What intrigued me was that the signal carrying McCarthy’s voice was in the room, everywhere, but only useful to us at a very particular point on the radio spectrum. This radio spectrum is a section of the whole electromagnetic spectrum. The latter spectrum is the full range of radiation in various wavelengths – X-rays, gamma rays, visible light, radio waves etc. Radiation is packages of energy, invisible, able to penetrate space, most objects, sometimes dangerous, sometimes helpful.

We receive radiation from the sun. It comes through our atmosphere, some bounces off clouds or surfaces like snow and ice, or even tarmac, warming the surface before heading back into space. This radiation or packets of energy passing back up through the atmosphere runs into the molecules of the various gases in the atmosphere. Most of these gases have no effect on this outgoing energy. About 1% of them do interact and they are the greenhouse gases – water vapour, CO2, methane, ozone and a few minor ones.

This interaction fizzes up the molecule, slowing down the outgoing radiation and heat is detained a little longer than it might be. That is the nub of global warming. Thank goodness that radiation does not go straight back into the atmosphere. We would be very cold if it did. The theory of global warming is that by adding greenhouse gases there are more interactions, therefore more warmth.

Methane is one of those molecules that gets excited by radiation bumping into it. But, here is the critically important thing, the issue that most so-called climate scientists do not want to go near. Methane can only operate at two very narrow bands on that electromagnetic spectrum. Methane may be all around us in minute quantities but most of it is of no consequence because it is only effective in two narrow wavelength spots. It gets worse. One of the wavelengths that methane can operate in there is no radiation to interact with. It does nothing. Nada. Zilch. See the diagram below.

But wait! There’s more. The other wavelength that methane operates in is dominated by water vapour. For every two methane molecules trying to interact with the out-going radiation there are 5,000 to 8,000 H2O molecules all chasing the same radiating energy. Methane doesn’t get a look in.

Too many scientists and commentators want us to focus on the relative strength of each individual molecule and what harm an extra molecule can do. They don’t want to go on in their calculations and face the reality of what happens in the atmosphere on the spectrum every minute of the day. If they did the arguments about each molecule’s potency and what happens when extra molecules of gas are added to the atmosphere become redundant and have no credibility in science.

Analogies can help us understand relative size and strength. If the whole of the atmosphere was a rugby field all the ruminant methane from all the world's sheep, goats, cattle, bison, etc would represent an area 40mm X 40mm or an inch and a half square. New Zealand’s contribution would be about a quarter the size of your little fingernail.

It is no wonder that the country’s leading climate scientists and IPCC contributors admitted under pressure that our sheep and cattle are warming the planet at 4 millionths of a degree C per year. And that was calculated before the dominance of water vapour was factored in.

For that infinitesimal, impossible-to-measure amount there are apparently serious and intelligent people demanding we slash our dairy herd by over 20% and remove at least 5% of sheep and beef farms.

As my grandson would say, “what are they smoking, Pop?”.

Owen Jennings is a former ACT MP