My past fears about climate change

Sometime in the 1980s, on an August day, driving through southern England, I noticed dark, very heavy clouds stretching across the whole sky. I could not remember ever before seeing such a cloud formation in southern England in August. It was so different to the summer cloud patterns I remembered seeing as a child. I wondered if a change was occurring in the weather patterns. Not long afterwards, I heard about the hypothesis of anthropogenic (or, in plainer language, ‘human-made’) global warming — as it was called in those days. I came to take the idea very seriously. Weather incidents, such as southern Britain being hit by the tail end of a hurricane in 1987 and a period of relative drought in the early 1990s, reinforced my thinking.

For these reasons, I readily accepted what was being proposed by the IPCC (Intergovernmental Panel on Climate Change) from the late 1980s onwards: that climate change was real, was caused by a human-generated increase in CO2 in the atmosphere, and was a potentially devastating threat to humanity. My trust was strengthened by the growing discussion about ‘chaos theory’, especially the notion of the ‘butterfly effect’ — the idea that small changes in one aspect of a non-linear system (such as the system of weather and climate) can lead to significant changes in the whole system over the long term. Thus, I came to believe strongly that a rise in CO2 could cause a major, even catastrophic, effect on climate.  I also thought it must be true, or at least highly likely, because scientists were advocating it, and politicians were taking it seriously. I did not think of questioning their hypothesis. From my present viewpoint, I was very naïve.

In the late 1990s I bought a textbook on weather and climate.  It showed me that weather systems were even more complex than I had thought. Still, it did not shake my faith in the IPCC and its associated ‘climate lobby’ — the scientists, politicians and journalists who promoted the idea that human-made CO2 was a major threat. As a Buddhist, I felt concern to alert my fellow Buddhists to the danger. On that basis, I advised the team at a Buddhist retreat centre in the lowlands of Norfolk to sell the property and move somewhere higher above sea level. After all, if the Greenland and Antarctic land ice were to melt, the sea level would rise very substantially.

But the message came back from the retreat centre team that they had been advised that a massive rise in sea level was not being predicted. Naturally, I felt some relief about this. I was also pleased that the retreat centre would probably not have to move. After all, it would have involved much trouble and expense. While I retained my belief in anthropogenic global warming, my sense of impending disaster diminished, and my interests shifted to other topics. Until a few years ago, I did not study climate further.

Ironically perhaps, while my own anxiety has diminished, that of other western Buddhists has grown considerably. To some extent, this is not surprising, as it simply reflects growing anxiety in the wider world. In the last few years, some Buddhists have begun to participate in protest groups that disrupt the functioning of society. One such Buddhist climate campaigner has written a book that attempts to connect Buddhist teachings to climate activism (we reviewed it here in Apramada in December 2021). All in all, it seems that alarmist views about human-made climate change are at least as prevalent among us western Buddhists as among the public at large — perhaps more so.

If such alarmism takes a deeper hold, what will be the result? Governments are already devising energy policies that will, I suspect, cause significantly more suffering than is likely to come from human contributions to a changing climate. It is sad to see Buddhists campaigning for even more radical measures, which if implemented would compound the misery. I fear that, as could have happened with my own episode of climate anxiety in the eighties and nineties, the most likely outcome will be unnecessary trouble and expense, but on an enormous scale. If the present article goes even a little way towards forestalling that outcome, at least among Buddhists, my words won’t be wasted.

During the long lull in my interest in the climate, I became very interested in the history of ideas. This included examples of various forms of flawed science, even pseudo-science, that have arisen over the last two hundred years, together with the political beliefs associated with them, and their detrimental effects on society throughout those centuries. In particular, I cast a critical eye on the absurd mathematics associated with neoclassical economics, the sinister eugenics of ‘Social Darwinism’, and the scientific pretensions of Marxism. Looking back, I see that these studies made me more alert to the propensity of people — often intelligent, educated, and idealistic people — to embrace erroneous and harmful beliefs, and indeed to become fervent missionaries for such beliefs. Nowadays, I see evidence of a similar propensity in alarmist claims of a ‘climate emergency’, and the highly partial ‘scientific’ account of climate that underpins such claims.

The Limited Warming Power of Carbon Dioxide

This realisation first began to dawn on me when I came across a graph showing climate data for the last four hundred thousand years.¹  The data came from an international project, located at the Russian Vostok station in East Antarctica. The scientists had drilled deep into the ice to sample traces left by weather patterns over millennia. Such traces can serve as proxy evidence for natural long-term variations of climate. The graph based on the Vostok ice-core data showed wavy lines representing average levels of Carbon Dioxide (CO2) and temperature. It was clear the two tended to go up and down together (with some small variations). However, given the graph’s large timescale, it was not easy to tell whether a rise or fall in each occurred at the same time or with some delay between them. The correlation was perfectly clear at a glance, but the direction of causation between the two — if any — was less so.

The graph also included lines for temperature and CO2 levels since the industrial period began. It struck me that the past correlations between average temperature and CO2 had apparently broken down over this relatively shorter period. Since the industrial revolution, the CO2 level has risen significantly, but temperature only slightly. If the old correlation had continued, the world’s average temperature would now be much higher than it is. Perhaps, I thought, that might be due to a time delay in the impact of CO2 on temperature. However, the climate lobby tended to argue that a rising CO2 level has a relatively more immediate effect on temperature.

Then came a crucial discovery. I learned that the ‘greenhouse’ effect directly caused by CO2 is limited. Media coverage of climate change tends to create the impression of a simple linear relationship — that increasing CO2 will lead to a proportional increase in temperature, with no end in sight. Yet as my old climate textbook stated (but did not explain), the relationship between an increase in CO2 and the resulting temperature increase is in fact logarithmic: the more CO2 there is in the atmosphere, the smaller the effect on temperature of adding yet more. The reason is that CO2 absorbs radiation only within certain narrow wavebands. If most of the radiation in those wavebands has already been absorbed, adding more CO2 can have little further effect. Put simply, the warming power of CO2 is subject to a law of diminishing returns.²

It seemed to me that this fact should allay, at least to some extent, public fears that we are in the grip of a ‘climate emergency’ caused wholly or mainly by human-made CO2. True, the climate lobby claims that the direct effect of CO2 may be amplified through positive feedback within the climate system. However, these claims are based on problematic assumptions — a point I will return to below, in my discussion of computerised climate modelling.

My realisation about the limitation of the warming power of CO2 led me to revisit the idea that warming in pre-industrial millennia had been caused by increasing CO2 levels. The Vostok graph, you will remember, showed a correlation between the CO2 levels and temperature. The climate lobby typically infers from this correlation that the former drove the latter. But is that true? A closer look at the Vostok data and at subsequent ice-core data reveals that in fact temperature increases typically preceded rises in CO2 levels.³ This is compatible with the fact that the warming of the world’s oceans causes them to release CO2.

Moreover, the Vostok graph also included a plot of the amount of energy received from the sun. This solar energy input is called ‘insolation’. It was clear that, prior to the industrial revolution, the major fluctuations in temperature and CO2 were both correlated with a third variable — a cycle of insolation changes. When insolation went up, they both tended to increase, and they both declined when insolation went down. There was also a clear pattern of decreasing averages over four cycles of insolation, and then a strong increase after the rise of every fifth peak of insolation. This strong rise seemed to occur after a previous relatively low insolation peak.

The amount of insolation reaching the Earth’s outer atmosphere does not depend upon CO2 levels, or anything in the atmosphere itself, but upon external factors, such as variations in the distance between the Earth and the sun. Before the industrial revolution, the major fluctuations in temperature and CO2 levels were mainly caused by changes in insolation. This led me to a belated but simple realisation: that it was essential to account for the effects of natural phenomena on climate in order to assess how much human activities may be adding to, or subtracting from, that natural variability. It is terrible logic, and bad science, to leave out any significant natural causes of climate change, when estimating what effects CO2 may have.

The fluctuations of insolation I have mentioned are primarily caused by the ‘Milankovitch Cycles’.  These are cyclical variations, over periods of thousands of years, in the shape of the Earth’s orbit and the tilt of the Earth’s axis. In the northern hemisphere, during certain phases of these cycles, the heat from the sun in the warmer months is not enough to melt all the new ice and snow deposited in the colder months. Accordingly, the total ice and snow cover increases year-on-year. The result is an ‘ice age’.

There are in fact two kinds of ‘ice age’. The longer type, lasting millions of years, is a relatively cool period in which ice covers some substantial proportion of the Earth’s surface (there have been warmer periods when this did not happen). We are in such a ‘long ice age’ even now. But during such long ice ages, the actual extent of the ice varies a lot. There are glacial periods (which are what we usually mean when we speak of ‘ice ages’) and inter-glacial periods. The inter-glacial periods are much shorter than the glacial periods (when much more of the northern hemisphere is covered with ice). The inter-glacial periods tend to start with the rise in temperature associated with every fifth insolation peak, as I described above. We are currently in an inter-glacial period, whose average temperature appears to have been somewhat lower than in previous ones. When the current inter-glacial period comes to an end, temperatures will go down and glaciation will once again extend further and further over the northern hemisphere — not a good thing for the population.

During our current interglacial — an era known as the Holocene, which began about eleven thousand years ago — what has been happening to global temperatures and CO2 levels? In my research, I came across a graph that provided an answer.⁴  Global temperature has gone up and down during the Holocene, with no obvious relationship to estimates of the CO2 levels. In fact, the warmest point of the Holocene is not now; it was about seven thousand years ago. Since that point there has, if anything, been an overall decrease in average temperature alongside a gradual increase in the average CO2 level. But what, you may ask, about the increase in temperature and CO2 since the industrial revolution? Within the overall decrease I just mentioned, there have been oscillations between warmer and cooler periods. Evidence for these can be drawn not just from proxy climate data, but from human records from ancient times. For example, there was the ‘mediaeval warm period’, and since then the ‘little ice age’. We are currently inhabiting a relatively warm period that seems to fit the overall pattern.

Thus, I came to realise that, over periods of a few hundred years and longer, climate naturally changes. Even over tens of years, climate, or predominant weather patterns, can change due to natural causes. This made me very seriously question the hypothesis that significant and dangerous global warming was being caused solely or primarily by a human-made increase in CO2 levels.

These realisations led me to a further question: have the scientists within the climate lobby properly taken into account the natural factors that cause climate change? Studying the subject further, I felt forced to conclude that they had not. There are many such natural factors. One is the influence of the oceans (there are processes within oceans that can produce cyclic fluctuations in temperature over periods of decades). Another is the influence upon the Earth’s atmosphere of the sun’s magnetic field, which affects the amount of ‘cosmic rays’ that reach the atmosphere and stimulate cloud development.⁵ Much remains unknown about the effects of such factors. Scientists inside the climate lobby, if they take account of these factors at all, must do so on the basis of assumptions that may not reflect the uncertainty involved, and may be coloured by a prior commitment to the belief that human-made CO2 is the key to warming.

Unreliable Climate Models

But now I must turn to another important realisation that came to me during my investigation of climate change. This concerns computerised mathematical modelling, which is at the heart of the IPCC’S case for the dangers of anthropogenic global warming. Such modelling attempts to predict temperature increases in the future. However, as the IPCC itself stated in its 2001 report:

In climate research and modelling, we should recognise that we are dealing with a coupled nonlinear chaotic system, and therefore long-term prediction of future climate states is not possible.

IPCC 2001 Report, Section 14.2.2.2, p774

This admission is remarkable, because the claims and predictions about climate disasters made by the IPCC and the climate lobby are crucially dependent upon such modelling. However, typically these models do not give accurate predictions. Almost without exception, they have made predictions of temperature increases above those actually measured in the period they cover.

It is crucial to understand that such modelling, by its very nature, has serious limitations.⁶  Weather and climate are so complex that running reliable long-range simulations of them on computers is impossible. The computational power required to simulate the detailed development of climate is immense. In effect, the use of existing computer models to forecast climate is comparable to using a marble and a few matchsticks to make an accurate sculpture of a human individual.

Moreover, deeply problematic assumptions are built into the models, concerned with the interaction between increasing CO2 and water vapour (itself a greenhouse gas). Such assumptions are at the root of current climate alarmism. Without them, as we have seen, the logarithmic effect of CO2 on temperature is limited, and probably too small to justify prophesies of catastrophic climate change. The key assumption is that the small increase in temperature directly due to CO2 is amplified by a knock-on effect upon the level of water vapour in the atmosphere.⁷ The trouble is that the actual interaction between CO2 and water vapour, and of the effects of increases in the latter on temperature, are extremely complex and hence extremely uncertain.

That uncertainty centres on the question of how the extra water vapour will translate into cloud formation, and what sort of feedback the clouds will have upon temperature. Clouds have a complicated effect, sometimes acting like a blanket (and thus warming), sometimes reflecting insolation (and thus cooling). But where does the balance lie? The IPCC believes that positive feedback will outweigh negative but admits to a wide range of uncertainty. It claims that a doubling of CO2, together with associated positive feedback, will eventually produce a long-term global temperature increase somewhere in the range of 1.5C to 4.5C. At the lower end, this would be within the limit that the IPCC itself recommends in order to avoid serious problems.

But apart from the uncertainties around feedback, the computer models have also typically omitted considerations of various other natural factors that affect atmospheric temperature levels — for example the various ways in which solar activity, such as sunspot cycles, affects weather and climate. Without such considerations, any observed increase in temperature due to these effects will erroneously be attributed to the human-caused rise in CO2. We must also keep in mind that, as mentioned above, ice core samples with better time resolution than the Vostok ones have shown that, before the industrial age, temperature rises preceded rather than followed a rise in CO2. This fact is hard to reconcile with the idea that CO2 has been a major contributor to temperature changes over the last few hundred thousand years.

In general, the more I studied the actual science of climate and weather, the more I appreciated its complexities, and the more problematic became the hypothesis of dangerous anthropogenic warming. That hypothesis has, from the outset, been based upon questionable assumptions that ignored the complexity of the scientific issues involved.

Despite this, the hypothesis has increasingly flourished since the founding of an international political organisation, the IPCC, in the 1980s. Ironically, only a few years earlier, in the 1970s, any anxiety about climate had focused on the idea that we were heading for another glacial period — the very opposite of ‘global warming’. This rapid about-face from the 70s to the late 80s is hard to understand solely on the basis of the growth of scientific knowledge about climate during the period. What is more, concern about human-made climate change has now spread far beyond the campuses of universities and the corridors of power. Over the last decade a growing focus on climate in the media has led to an explosion of popular climate alarmism. This is reflected, as I mentioned at the start, in the disruptive protests of activist groups. Such groups, which in some cases have an explicit ideological agenda quite unrelated to climate science, make claims of impending catastrophe that go far beyond the position of the IPCC.

Clearly, there is something here that demands explanation. Why has the hypothesis of dangerous human-made warming come to hold such a tight grip, not just on the media and the public, but on governments, and even on the scientific community — or at least, upon the public face of that community? Adequate answers to these questions would extend the bounds of this article too far, and therefore must await a further article. Meanwhile, I will say here that I have come to realise that the hypothesis of anthropogenic climate change is yet another example of the entanglement of science with political beliefs, comparable to those I had studied before. Nowadays, when I recall those heavy August clouds, they are a reminder not just of the complexity of the Earth’s climate, but also of the danger of jumping to simplistic conclusions about it.

1. https://www.antarcticglaciers.org/glaciers-and-climate/ice-cores/ice-core-basics/
2. Since the pre-industrial era, the concentration of CO2 has risen from about 280 parts per million to about 412 (according to a 2019 estimate by NASA at The Atmosphere: Getting a Handle on Carbon Dioxide – Climate Change: Vital Signs of the Planet (nasa.gov)). This is a substantial percentage increase (about 47%), but from a low starting point. Over the same time, average global temperatures have risen by a modest one degree Celsius. Even if we attribute all that single degree to the added CO2 (which, as this article goes on to show, is highly questionable) it is clear the relationship between CO2 and temperature is not linear. In fact, the shape of the logarithmic curve shows that, for each additional tonne of CO2 in the atmosphere, there is a progressively smaller increase in temperature. This is typically not mentioned. What is often mentioned is a hypothetical temperature increment for a doubling of the CO2 concentration compared to the pre-industrial level. What exactly is the size of that increment? Is it dangerous to humanity? The answers to these questions depend on, among other things, whether they refer to the effect of CO2 alone at the point of doubling (Transient Climate Response or TCR) or to the long-term effect within the total climate system (Equilibrium Climate Sensitivity, or ECS). The IPCC itself acknowledges (in its 2014 report) that the TCR may be as little as 1C (it claims ‘high confidence in a range of 1C to 2.5C). Predictions about ECS are discussed below, in the section on computerised climate modelling.
3. The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka (manfredmudelsee.com)
4. An overview to get things into perspective  Figure 3, Ice core samples of last 11,000 years.
5. Space weather climate forcing: https://www.youtube.com/watch?v=NYoOcaqCzxo
6. Climate Modelling: https://www.thegwpf.org/content/uploads/2017/02/Curry-2017.pdf
7. The permanent temperature increase resulting from the combined effect of increases in CO2 and water vapour levels (together with other forms of positive feedback) is called Equilibrium Climate Sensitivity (see also note 2 above).