To most of us the climate signals are rather confusing. Whilst the press has often provided stories of shrinking ice-caps with commentary from global warming alarmists insisting this is evidence that increasing level of atmospheric CO_{2 ,} the same folk seem rather bewildered by the record cold conditions now blanketing North America.

If the truth were to be told we have little understanding of these climate change events. Even the nomenclature has changed. Initially environmentalists talked of global warming, then backed off a little and started talking about climate change. In a report I read recently the phenomenon was now described as climate disruption. The broadening of the definition seems to be driven the lack of persistent evidence about warming and allowing a raft of other phenomena such as bushfires, cyclones, floods, droughts etc. to try and make a case for the supposed impending catastrophe.

Only forty years ago, there seemed to be a growing consensus that, far from global warming, a Little Ice Age might be imminent. Shortly after this, scientists started talking about the “greenhouse effect” and how radiant energy from the sun was polarised in the earth’s atmosphere, reducing the amount of energy that could be reflected off the earth’s surface and be subsequently radiated back into space. The offending components of the earth’s atmosphere that create this effect are the “greenhouse gases”.

Greenhouse gases constitute a very minor percentage of the earth’s atmosphere. (That does not mean to say they still might have a significant impact.)

Those gases responsible for the greenhouse effect are largely:

• Water vapour,
• Carbon dioxide,
• Methane,
• Surface level ozone, and
• The oxides of nitrogen and fluorinated gases.

By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around 1% at sea level, and 0.4% over the entire atmosphere. Both water vapour and methane are more potent greenhouse gases than carbon dioxide.

Water vapour creates a positive feedback loop. As the atmosphere warms, more water evaporates. Higher concentrations of water vapour aid further warming because of its greenhouse effect which in turn evaporates more water, and so on.

The concentration of methane in the atmosphere (like CO₂) has increased with increased human habitation. Humans have added to the methane load in the atmosphere by such activities as livestock farming, the burning of carbon based fuels, and the decomposition of waste in landfill.

Despite this, the attention of the environmental movement has largely been on the concentration of CO₂. Whatever part CO₂ plays in global warming, one thing we know for certain is that increasing levels of CO₂ promotes plant growth and there is considerable evidence to suggest growing levels of CO₂ in our atmosphere are contributing to a re-afforestation of many denuded landscapes. This (in contrast with water vapour) constitutes a negative feedback loop. As more plants grow, more CO₂ is absorbed from the earth’s atmosphere aiding a return to a steady state situation.

You should note from this discussion that the atmospheric greenhouse impacts are very complex and there is little evidence to suggest that scientists can adequately model this dynamic.

Now we have merely looked at the atmospheric effects of greenhouse gases. There are far more influences on the temperature of the earth’s surface than this.

Science writer, Matt Ridley, recounts that scientists have long argued that changes in the earth’s surface temperature are correlated with changes in the orbit of the earth around the sun. These changes are known as:

• Eccentricity,
• Obliquity, and

These orbital variations are each cyclical.

Eccentricity, takes into account the variations in the elliptical orbit of the earth around the sun. The more elongated the ellipse, the more extreme are the temperatures. These changes occur over a cycle of about 100,000 years.

Obliquity, is related to the tilt of the earth’s axis which determines which part of the earth’s surface is closest or furthest from the sun. The wobble of the axis of the earth moves in a cycle of some 40,000 years.

But to further complicate matters, the earth’s axis itself rotates over time and that movement is called precession and has a cycle of some 20,000 years.

As a result of these factors there are variations in not only the overall surface temperature of the earth but how temperature differs around the global surface.

The effects of these phenomena, as indicated, occur over long cycles of time.

But there is yet at least one other significant variant impacting world climate, and that is sunspot activity. Many climate scientists agree that sunspots and solar wind could be playing a role in climate change, but most would concede it is minimal. But there are many as well, who would aver that CO₂ concentration in the atmosphere might also be a minimal influence.

So what might we deduce from all this? Since scientists proposed the greenhouse effect this seems to have dominated the thinking of environmentalist activists, and what’s more their focus seems to have been almost exclusively on CO₂ concentrations, despite the deleterious effects of other greenhouse gases and the impacts on the earth’s climate of the other mechanisms mentioned above.

Accordingly, for those that believe global warming presents an imminent disaster, the emphasis has been on the reduction of CO₂ emissions and the climate alarmists have been trying to convince us to make huge resource commitments to reducing atmospheric CO₂ levels.

Let’s approach the issue with three questions.

Firstly is global warming occurring and if it is at what rate?

Secondly if we agree global warming is occurring is it due to elevated concentrations of atmospheric CO₂.

Finally, if increasing levels of atmospheric CO₂  is the cause, what is our appropriate response?

Let me from the outset concede this a matter of my personal opinion. But I am not moved by the contention from the catastrophists that the science is settled. It clearly is not. There has yet to be climate models produced that accurately forecast how climate is changing. And there has been considerable shifting of ground in the last decade or so which suggests scientific opinion is far from settled.

I personally suspect that global warming is happening although I could not categorically attest it is the case. If global warming is occurring it is seemingly occurring at a rate which appears to be much less than the catastrophists would have had us to believe a decade ago. But for the sake of argument let us assume for the time being that the surface of the earth is going through a warming phase.

What is causing such assumed global warming? I confess I could not be sure. The factors influencing the temperature of the earth’s surface are so many and complex, I think it is rather courageous to hold it would be predominantly due to increasing concentrations of atmospheric CO₂. But for the sake of argument, let us assume that not only do we have global warming but that the prime causative factor is CO₂ levels. (Unfortunately those who disagree with this assessment are denigrated by the environmental warriors as Luddites, troglodytes and worse.)

(Research reported recently in a paper published in Nature suggests the earth is not as sensitive to CO₂ levels as scientists have previously thought. It predicts that temperature rises resulting as a result of this particular greenhouse gas will be both smaller and slower than originally thought.)

The international response to global warming has assumed the key role of CO₂.This is reflected in the Paris Agreement adopted in December 2015 where 195 countries pledged to reduce their CO₂ emissions. But even if we concede that CO₂ is the issue, the Paris Agreement doesn’t withstand scrutiny. The ambition of those participating in the emissions reduction regime is to limit global warming to less than 2⁰C and hopefully to 1.5⁰C. Even if the Paris Agreement is fully implemented, according to the UN it would only achieve 1% of the reductions required if climate modelling is to be believed. The UN Framework Convention on Climate Change acknowledges on the basis of their current modelling, to keep temperatures from rising more than 2⁰C, CO₂ emissions need to be cut by 6,000Gt by 2030. Even if all the targets set at the Paris Convention were met (and there is already evidence of considerable slippage) only a reduction of about 60 Gt would be achieved.

The major initiatives to reduce CO₂ emissions have focussed on reducing the consumption of fossil fuels for electricity generation. But as one of the world’s foremost energy experts, Vaclav Smil points out:

Claims of rapid transition to a zero carbon society are plain nonsense. Even a greatly accelerated shift towards renewables would not be able to relegate fossil fuels to minority contributors to the global energy supply anytime soon, certainly not before 2050.

The director of the Copenhagen Consensus Centre, and former director of the Danish government’s Environmental Assessment Institute in Copenhagen, Bjorn Lomborg believes that global warming is real. However he is despised by Australian academics and his efforts to set up a research instituted were thwarted because he believes the cost of mitigating CO₂ emissions is excessively high and humankind would benefit more by reallocation of such resources to other ends. Lomborg believes that spending this money helping alleviate world hunger would provide substantially higher benefits than reducing CO₂ emissions. Lomborg reports:

This year the IEA (International Energy Agency) evidence shows the world will spend $US125 billion on subsidising solar and wind. During the next 25 years more than $US3 trillion will prop up the grand “achievement” of meeting less than 3% of the planet’s energy needs. In 2040, even with a carbon tax and the Paris Agreement fully implemented, the IEA finds that on average non-hydro renewables will be the most expensive power you can produce.

Lomborg has been quoted as saying:

Just because there is a problem doesn’t mean that we have to solve it, if the cure is going to be more expensive than the original ailment.

In the forlorn hope of significantly reducing CO₂ emissions the rush to renewables is already hurting Australia. It has contributed to rapidly increasing energy costs and in those states which have pursued renewables most aggressively the security of supply of electricity is under threat. As I write this essay following two 40⁰C days in South Australia hospitals have been forced to reduce their power demand and heavy industrial users have had to reduce load to avoid blackouts. Additionally, in the last decade and a half electricity prices in Australia have soared. We have gone from having some of the cheapest electricity which attracted energy intensive industries to our shores, to having some of the most expensive which is threatening the viability of such industry. Given that Australia’s contribution to the world’s CO₂ emissions is so minimal we might legitimately ask (as Bjorn Lomborg does) what have we achieved by these efforts except to burden the Australian economy with over-inflated electricity prices, unreliable electricity supply and impediments to industry that creates wealth and employment.

Now you might be surprised from what you have read above that I am in fact a proponent of renewable energy. In my professional career I promoted renewable energy. But back in the mid-nineties things were different – there was only a modest renewable energy target (2%) and there was a plausible path to a future where renewables would be the majority of generation. That future was built on gas-fired generation as the transition technology. Closed-cycle gas turbines emit considerably less CO₂ per MWhr of energy generated than do conventional coal-fired plant. But in our minds the transition to renewables making up the majority of generation was expected to take many decades. Such a transition would have seen high levels of despatchable generation available and far more synchronous generation available on the grid which would have maintained system stability.

But this approach has been largely thwarted by the attack of the environmental movement on the gas industry.  This has all been exacerbated by politicians taking populist positions on renewable energy with little understanding of the impacts of these technologies on the system.

Australia, of course is not the only country suffering from the rush to renewables. Germany, a long-time supporter of renewable energy, now seems very unlikely to be able to fulfil its pledge in the Paris Agreement to achieve a 40% reduction in CO₂ emissions. One electricity company in Germany has been forced to spend more than $1.5 billion to ensure a stable grid in its area as a result of the proliferation of renewable generation. This reflects some of the issues being confronted in South Australia and Victoria.

Environmentalists continue to talk about “cheap” renewable energy. Renewable energy is not cheap. It might be cheaper to install a MW of wind power, for example, than a MW of coal-fired plant. But the problem is that output of a wind turbine is intermittent and that MW is only available when the wind is blowing. Without the back up of despatchable plant like coal-fired, gas-fired and hydro there is no certainty that the demand can be reliably supplied. It was reported that during the peak demand period in South Australia during the heat wave conditions last week that its wind generators were only delivering 6.5% of their installed capacity. So just when the system most needed their output they were generating at minimal capacity requiring the importation of large amounts of energy sourced from coal-fired plant and hydro generation.

So let me try to summarise the lessons from all of this. (I hasten to add these are my opinions only. I don’t have a closed mind on global warming and will continue to study all points of view.)

• Global warming may be occurring. There is certainly some relatively short term evidence to that effect. However it might well be there is a longer cycle returning us to another Little Ice Age. It is premature in the extreme to proclaim that “the science is settled”.
• If global warming is occurring it is still unclear that it is due to the accumulation of CO₂ in the earth’s atmosphere. As we saw earlier there are other, more potent, greenhouse gases and many other phenomena other than the “greenhouse effect” impacting on the surface temperature of the earth.
• Even if global warming is occurring and it is a result of CO₂ emissions, mitigation costs are hugely expensive. We might want to examine whether humankind might benefit more by spending this money, or at least some of it, in other ways (as Bjorn Lomborg has suggested). We should not discount adaptation strategies which would be far less costly than mitigation strategies.
• If we persist in using the reduction of the use of fossil fuels and the development of renewable energy as our major strategy for reducing CO₂ we should be more cognisant of the cost to our economy and to the impact on the reliability of our electricity supply.