This week we launch a new series exploring a rival theory of global warming proposed by Professor Qing-Bin Lu of the University of Waterloo Department of Physics here in Canada. Lu believes that 20th and 21st century climate change was man made, but not from CO2 emissions. The culprit, he argues in a 2023 paper, was another class of greenhouse gases (GHGs) called halo-GHGs, which climate models do allow to play a role in warming but they assume it’s small compared to CO2, whereas Lu’s work on the physics of halo-GHGs convinced him that the reverse was true, that the interactions of cosmic rays and electrons with halo-GHG's cause relatively large climatic effects, which he calls the CRE model. By comparison, in his estimation, CO2 hardly matters. And it’s a theory that’s relatively easy to test empirically because halo-GHGs including the famous CFCs (chlorofluorocarbons) used to be used as refrigerants and foam aerators until it was discovered they could migrate up into the stratosphere and damage the ozone layer which protects us from harmful ultraviolet radiation, so the 1987 Montreal Protocol was signed that banned their use globally. And the Protocol worked, so halo-GHGs began declining while CO2 kept increasing. And since they are trending in different directions, we can now begin to figure out which matters more. Lu has proposed six indicators that we need to examine. This week we look at #1, the question of Outgoing Longwave Radiation or OLR at the top of the atmosphere.

Before we get to that indicator, we need to review some principles. Even if the term halo-GHGs isn’t familiar you’ve heard of the most famous example, those CFCs that were blamed back in the 1980s for creating holes in the ozone layer and exposing people to too much UV radiation leading to sunburns and skin cancer. But as is so often the case the metaphors created a lot of inaccurate pictures in peoples’ heads.

There isn’t an ozone “layer” separate from the rest of the atmosphere and working as a shield unless it gets a hole torn in it. Instead that gas (O3, itself also a greenhouse gas and ironically a dangerous pollutant at ground level though a helpful protection higher up) is present in varying concentrations from the surface to the top of the stratosphere. And so of course there aren’t “holes,” there are areas with more or less of it mixed in with all the other gases that make up the atmosphere including, predominantly, nitrogen (78.08%, with 20.95% oxygen, 0.93% argon and everything else a trace although these numbers from NASA exclude water vapour, at 0.25%). During the “ozone hole” scare the maximum reduction in ozone concentration happened over Antarctica which, if it had to happen anywhere, was as good a place as any because even in the summer there is so little sunshine and so few people that the risk of widespread sunburn was minimal.

Another important point is that halo-GHGs are widely considered to have strong greenhouse properties. The reason conventional models treat them as minor is that they’re pretty rare in the atmosphere even compared to CO2’s roughly 400 parts per million. But unlike CO2 they aren’t “crowded out” by water vapour.

For a gas to have a greenhouse effect its molecules need to have bands in the infrared spectrum where they can absorb energy. And water vapour has a whole lot of those, occupying most of the spectrum in fact, so the other GHGs only matter if they have bands to themselves. It’s comparable to a window much of which has been painted over with black paint (water vapour), so if you add a patch of red paint (another GHG) to part of the black area it doesn’t make it any harder to see through because it’s already opaque. Now, CO2 does absorb in several bands, but only one tiny one isn’t also occupied by water vapour, whereas halo-GHGs have wide bands. Moreover, Lu argues, CO2 levels are already high enough that adding more doesn’t do much warming, whereas changes in the halo-GHGs do have a big effect, according to his analysis and that of many other studies he cites.

If he’s right, it’s very good news for any alarmists who don’t actually like being alarmed. Because of the Montreal Protocol, the levels of halo-GHGs in the atmosphere began to level off in the 1990s and their “radiative forcing” (in common parlance “greenhouse”) effect has slowed down. And it could happen not only because some politicians made high-sounding pledges, but because there were a range of cheap, reliable alternatives to CFCs in particular. CO2, by contrast, necessarily comes from burning fossil fuels and so far no one has figured out a cheap and reliable substitute for them. So CO2 keeps going up and according to the IPCC so does the radiative forcing from it. If they’re wrong, and CO2 is mostly harmless while easily eliminated gases are dangerous, the crisis suddenly becomes easy to solve with no painful, controversial and uncertain “green transition”.

If. But how do we tell? It’s often easy to propose a plausible theory and a lot harder to find reliable evidence. And here Lu proposes six markers for us to examine of which the first, finally, is the measure of the greenhouse effect itself, namely outgoing long-wave radiation (OLR) from the top of the atmosphere.

A critical element of real global warming theory, as opposed to the childish cartoons of a space blanket way up at the edge of the sky, is that as GHG levels rise infrared energy radiating back from the Earth after incoming visible and UV light warmed it gets absorbed in the relevant bands of the spectrum by various GHGs and then scattered, so less gets back out into space at those frequencies than would with fewer or no such gases. OK, says Lu, let’s look. Is OLR actually decreasing as CO2 rises, and is it decreasing in the specific bandwidth where CO2 operates and water vapour does not?

He reports on three satellite studies using satellite data covering 1970-1997 that measured changes in the OLR from the top of the atmosphere. He charts their findings relative to climate model predictions as follows, with the black line being observed data and the red one model predictions:

The horizontal axis shows the frequency of the energy from low to high (sort of like bass to treble) across the infrared part of the spectrum (so relative bass to treble in what is all bass compared to visible light). The vertical axis shows changes in radiation as measured in units called “brightness temperature” here denoted delta T. The black line shows the observed data. If the line is above zero that means there was an increase in outgoing radiation at that frequency between 1970 and 1997, while if it is below zero there was a decrease.

The unique absorption band of CO2, the orthodox main culprit in man-made global warming, is at around 650 on the horizontal axis. And naturally from 600 to 700 cm the red line showing model predictions is below zero. Since atmospheric CO2 levels rose so much over that time the energy escaping to space in those bands should have gone down, according to the models and the theory they embody and uphold. Indeed it must have. But it didn’t.

The black line showing actual empirical observation of data is above zero, meaning radiation escaping in that part of the spectrum actually went up. Which means, fairly directly, that increased CO2 forcing could not have played a role in climate changes during that time because CO2 forcing did not increase.

By contrast with CO2, halo-GHGs are active in a broad band in the 800-1,300 region, where the models predict little or no overall change and the data show an increase at the lower end from 800 to 1,000 or so, then nothing from there to 1,200 and a drop from 1,200 to 1,300. However, as we will learn, that pattern over the period from 1970 and 1997 that these charts combine (there is no time axis) matches the pattern where during this period they first increased, depleting ozone as they did, and then decreased while ozone recovered. The specific fingerprints of halo-GHGs will become clearer as we go through the remaining five key indicators in the weeks to come.