By Cardinal George Pell
Let me begin by thanking the Global Warming Policy Foundation for the invitation to deliver this lecture. It came as a surprise and I truly appreciate the honour. However I am more grateful for the existence of the Foundation and its sane and important contributions in this debate.
A word of two about the structure of the talk, because I examine the issue from a number of directions reflecting my own expertise. The central part discusses the scientific claims and demonstrates, I hope, that a scientific layman can cover and identify the basic issues.
After a brief theological introduction I explain why I chose to write on global warming, while the central section is followed by a brief discussion of the propaganda wars, a longer discourse on the existence of the Medieval Warm Period, and concludes with some public policy questions and reflections.
At a recent meeting of the priests’ council in Sydney one parish priest asked me why I was commenting publicly on the role of carbon dioxide in the climate, because in the past the Church had made a fool of herself on a number of occasions.
I replied that I was well aware of at least some of these instances and that one reason why I was speaking out was to avoid having too many Christian leaders repeating these mistakes and to provide some balance to ecclesiastical offerings.
I first became interested in the question in the 1990s when studying the anti-human claims of the “deep Greens”, so I had long suspected that those predicting dangerous and increasing anthropogenic global warming were overstating their case. During the years 2008-09 it was dangerous for an Australian politician to voice dissent unless he was from a country electorate. Opponents were silenced. As I was not up for re-election and I suspected the Emperor had few if any clothes, I made a few more small public statements, never from the pulpit, never at a large public meeting.
What the science says:
Recently Robert Manne, a prominent Australian social commentator, following fashionable opinion, wrote that “the science is truly settled” on the fundamental theory of climate change: global warming is happening; it is primarily caused by the emission of greenhouse gases, especially carbon dioxide and it is certain to have profound effects in the future14.
These fundamentals are distinct, he acknowledges, from scores of other different questions. The author is secure in these fundamentals, dismayed and embarrassed by those who cannot make these distinctions especially as “the future of the Earth and of humanity are at stake.” Opponents are accused of “ideological prejudice and intellectual muddle”15.
His appeal is to the “consensual view among qualified scientists.” This is a category error, scientifically and philosophically. In fact it is also a cop-out, a way of avoiding the basic issues.
What is important and what needs to be examined by lay people as well as scientists is the evidence and argumentation which are adduced to back any consensus. The basic issue is not whether the science is settled but whether the evidence and explanations are adequate in that paradigm.
I suspect many educated people are like the insurance brokers working in this area, whom I heard of recently, who confessed they had never even begun to examine the evidence for themselves. I fear too that many politicians have never investigated the primary evidence.
Much is opaque to non-specialists, but persistent enquiry and study can produce useful clarifications, similar to the nine errors identified by the British High Court in Al Gore’s propaganda film An Inconvenient Truth16.
The complacent appeal to scientific consensus is simply one more appeal to authority, quite inappropriate in science or philosophy.
Thomas Aquinas pointed this out long ago explaining that “the argument from authority based on human reason” is the weakest form of argument17, always liable to logical refutation.
Underlying these models, we have a fundamental scientific problem, which has been usefully set out by Lord Monckton, quoting Edward Lorenz, the founder of chaos theory. In 1963 Lorenz wrote that in the instability of a non-periodic flow (and the evolution of the climate is ostensibly aperiodic) “prediction of the sufficiently distant future is impossible by any method, unless the present conditions are known exactly”18.
Lorenz continued that “in view of the inevitable inaccuracy and incompleteness of weather observations, precise, very-long range weather forecasting would seem to be non-existent”19, because our knowledge both of the initial state of the climate system and of how the climate responds to changes in external forces is incomplete20.
It is not generally realized that in 2001 at least, one of the IPCC Third Assessment Report’s Working Groups agreed: “In climate research and modelling, we are dealing with a coupled, non-linear, chaotic system, and therefore that the long-term prediction of future climate states is not possible”21.
Note that it is not just weather but also “future climate states” that are not reliably predictable in the long term. As Mark Twain said, “Climate is what you expect: weather is what you get.” Neither is predictable.
Professor Bob Carter, Dr. David Evans, Professor Stewart Franks, and Dr. William Kininmonth have succinctly stated the case for the sceptics, a case which so far has been completely ignored by the Australian media and political class. The conclusions of the 2007 Fourth Assessment Report of the UN’s Intergovernmental Panel on Climate Change (IPCC), they wrote, are “essentially reliant on computer modelling and lack empirical support”; its speculations on “the baleful influence of atmospheric carbon dioxide rest almost exclusively on unvalidated computer modelling that rests on unsubstantiated assumptions about the amplification effects of water vapour, clouds and other unverifiable factors.” The predictions based on these models “have been wrong for the last 23 years”22. During the decade since 2001 carbon dioxide has increased by five per cent, but the atmosphere has failed to warm23.
The influence of various solar mechanisms (such as sunspot activity) and changing ocean circulation, which are poorly understood, are “omitted from the climate models”24, as is the influence of major volcanoes such as the occasional mighty eruption of Krakatoa or Mount Saint Helens or the continuing eruptions deep in the ocean, brought to public attention by Professor Ian Plimer25.
While causal physical principles such as the greenhouse effect are known, much else has not been established definitively. Such uncertainties include the already-mentioned water vapour multipliers, sunspot activities and cloud formation, as well as deforestation, soil carbon and aerosols. We should also add variations of the earth’s orbital parameters, asteroid and comet impacts, and variations in cosmic rays26.
Claims of atmospheric warming often appear to conflict and depend critically upon the period of time under consideration.
Global temperature reached a twentieth century high in 1998, corresponding to the strong El Nino episode of that year. Subsequently, the continued warming anticipated by the IPCC did not eventuate, and, after first reaching a plateau, by 2010 temperature had cooled slightly. The failure to warm was accompanied by dominant La Nina conditions, and by a period of solar sunspot quietude.
The following facts are additional reasons for scepticism.
- Multiple lines of evidence show that in many places most of the 11,700 years since the end of the last Ice Age were warmer than the present by up to 2 degrees Celsius27.
- The ice-core records of the cycles of glacial and interglacial periods of the last one million years or so show a correlation between CO2 levels and temperature, but the changes in temperature preceded the changes in CO2 and cannot, therefore, have been caused by them. Carbon dioxide was probably out-gassed from the warming oceans and vice versa when they cooled28.
- The atmospheric concentration of carbon dioxide is generally the same everywhere, but temperature changes are not the same everywhere29.
The Battle for Public Opinion:
As a bishop who regularly preaches to congregations of every age and at widely different levels of prosperity and education, I have some grasp of the challenges in presenting a point of view to the general public. This helps me to understand the propaganda achievements of the climate extremists, at least until their attempted elimination of the Medieval Warming and then Climategate. I was not surprised to learn that the IPCC used some of the world’s best advertising agencies to generate maximum effect among the public30.
Since the climate had been changing – as Professor Plimer puts it, ever since that first Thursday 4,567 million years ago when the Earth began and the atmosphere began to form – I am not a “denier” of climate change and I am not sure whether any such person still exists.
Therefore the term “climate change denier”, however expedient as an insult or propaganda weapon, with its deliberate overtones of comparison with Holocaust denial, is not a useful description of any significant participant in the discussion.
In the 1990s we were warned of the “greenhouse effect”, but in the first decade of the new millennium “global warming” stopped. The next retreat was to the concept of “anthropogenic global warming” or AGW; then we were called to cope with the challenge of “climate change”. Then it became apparent that the climate is changing no more now than it has in the past. Seamlessly, the claim shifted to “anthropogenic climate disruption”.
These redefinitions have captured the discourse. Who would want to be denounced and caricatured as a “denier”?
Another more spectacular example of this successful spin is the debate on “carbon footprints”, on the advisability or not of a “carbon tax”. We all know that it is the role of carbon dioxide in climate change which is in question, not the role of carbon, but we continue to talk about carbon. The public discussion is almost entirely conducted in terms of “carbon footprints” and a “carbon tax”, provoking colourful but misconceived images of carcinogenic burnt toast and narrow, Dickensian chimneys being cleaned by unhealthy young chimney sweeps. It is brilliant advertising. But it is untrue.
My suspicions have been deepened over the years by the climate movement’s totalitarian approach to opposing views, their demonising of successful opponents and their opposition to the publication of opposing views even in scientific journals. As a general rule I have found that those secure in their explanations do not need to be abusive. Churchill claimed that in wartime “truth is so precious she should always be attended by a bodyguard of lies”31: but this approach should be anathematised in science.
I have discovered that very few people know how small the percentage of carbon dioxide is in the atmosphere.
Carbon dioxide levels in the atmosphere during the twentieth century are estimated to have risen from 280ppmv to about 390ppmv today, an increase of forty per cent. Yet today’s total CO2 concentration represents less than one-twenty-fifth of one per cent.
While opinions vary, one geochemist has calculated that only about five per cent of present atmospheric carbon dioxide is derived from burning fossil-fuels; that is, just 19 parts of CO2 per million parts of atmosphere32.
I can understand why the IPCC public relations advisers did not ensure that these statistics were presented vividly to the public, because they are no stimulus to alarm! In fact they seem to be a well-kept secret outside scientific circles.
Despite the fact that Wikipedia’s entry on air pollution now includes carbon dioxide emissions in a list of “greenhouse gas pollutants”33, CO2 does not destroy the purity of the atmosphere, or make it foul or filthy (the Oxford Dictionary definition of a pollutant). It is not a pollutant, but part of the stuff of life34.
Animals would not notice a doubling of CO2 and obviously plants would love it. In the other direction, humans would feel no adverse effects unless CO2 concentration rose to at least 5000ppmv, or almost 13 times today’s concentration, far beyond any likely future atmospheric levels.
A final point to be noted in this struggle to convince public opinion is that the language used by AGW proponents veers towards that of primitive religious controversy. Believers are contrasted with deniers, doubters and sceptics, although I must confess no one has dubbed me a climate change heretic.
The rewards for proper environmental behaviour are uncertain, unlike the grim scenarios for the future as a result of human irresponsibility which have a dash of the apocalyptic about them, even of the horsemen of the Apocalypse. The immense financial costs true-believers would impose on economies can be compared with the sacrifices offered traditionally in religion, and the sale of carbon credits with the pre-Reformation practice of selling indulgences. Some of those campaigning to save the planet are not merely zealous but zealots. To the religionless and spiritually rootless, mythology – whether comforting or discomforting – can be magnetically, even pathologically, attractive.
More than anecdotes
Remember Canute. The history of climate change provides no reassurance that human activity can control or even substantially modify the global climate, although humans can effect important local changes for good or ill.
In broad outline the history is uncontroversial. For 2.5 million years, northern Eurasia and North America were covered by ice sheets kilometres deep, and the earth has seen eleven strong glacial episodes (or Ice Ages) in the past million years. We live in an interglacial period which has now lasted 10,000-11,500 years.
The warmer interglacials usually last between 10,000 to 20,000 years, occurring at intervals of about 100,000 years. By these criteria one could argue that an Ice Age is now overdue, which perhaps contributed to the cooling scare in the 1970s.
Apparently the present eccentricity of the earth’s orbit is small, decreasing and likely to continue for 30,000 years, meaning that our current interglacial may be exceptionally prolonged35. A pleasant coincidence.
Controversies commence as we approach the Christian era as nobody seems too concerned about the Minoan warming of about 3,500 years ago. The Roman warming around 2,000 years ago provokes some heart burn, while we have seen attempts to erase the Medieval Warm period (850-1300AD) from history.
On February 7th, 2010 I had published a small piece on climate change in my weekly column of Sydney’s Sunday Telegraph which raised some of the issues I discussed earlier. This was referred by Senator Ian MacDonald of the Australian Parliament to the Bureau of Meteorology for comment, which was duly provided.
In a letter of July 8th, 2010 I replied to these comments.
On February 21st, 2011 Dr. Greg Ayers, Director of Meteorology, was granted leave to appear before the Committee to respond to my article and letter. His contribution was unusual, primarily for his diatribe against Professor Ian Plimer and his book Heaven and Earth – Global warming: The Missing Science (2009). 30,000 copies were sold in Australia in a few months, but Ayers denounced it as “simply not scientific,” “misleading to all Australians,” pseudo-science and a polemic36.
Dr. Ayers provided detailed responses on a number of issues, but a major topic was his defence of the Bureau’s claims that temperatures “in recent decades have been warmer than those of the Middle Ages”37.
The First (1990) and Second (1995) IPCC Assessment Reports had shown a Medieval Warm Period, warmer than the end of the twentieth century and followed by a Little Ice Age. Notoriously both the Medieval Warm Period and the Little Ice Age were eliminated in the 2001 Third Assessment Report following Michael Mann’s 1999 study on the last 1,000 years of climate.
Two Canadian academics, Stephen McIntyre and Professor Ross McKitrick, found Mann’s data misleading. The Wegman Report to the US Congress in 2006 upheld their criticisms as valid and their arguments as compelling38.
The deficiencies in the IPCC process were given even wider publicity when hundreds of emails were leaked or hacked from the University of East Anglia website in 2009, showing censorship and evidential irregularities.
Professor Bob Carter lists eight different recent scientific studies from 2000-08 on proxy data such as tree-ring records, borehole temperature methods, and deep cores in glaciers, lake beds and ocean floors which demonstrate the existence of the Medieval Warming with temperatures equal to or higher than today. Particularly significant is the 2008 study by Loehle and McCulloch compiled from eighteen high quality proxy climate records39.
Dr. Craig Idso40 has collected papers over the past quarter of a century from more than 1000 scientists in 578 research institutions in 44 countries, providing evidence by a multitude of empirical methods that, taken together, establish that the Medieval Warm Period was real, was global, and was warmer than the present. The comparatively few papers that oppose this evidence are written by a small, tight-knit group of computer modellers.
The historical data are equally clear and sometimes more compelling on the existence of earlier and warmer times, followed by the Little Ice Age, a cold snap of 500 years; two contrasting periods when the level of carbon dioxide in the atmosphere did not change despite greatly differing temperatures worldwide41.
Brian Fagan is the best-known climate historian, author of a string of books and editor of The Oxford Companion to Archaeology. He believes in twentieth century anthropogenic warming, but has no problem in accepting the evidence that in the Medieval Warm Period average summer temperatures were between 0.7° and 1.0°C above twentieth century averages, while Central European summers were up to 1.4°C higher42.
Commercial vineyards in England flourished 300 to 500 kilometres north of twentieth century limits. So popular were quality English wines then that the French tried to have their sale banned on the Continent.
In 1300 a farm owned by Kelso Abbey in southern Scotland had sheep and land under cultivation at 300 metres above sea level, well above today’s limits.
In Scandinavia and central Norway farming spread 100 to 200 metres further up valleys and hillsides. In this time forests in the Alps were between 80-200 metres higher than today43. Bitter winters were a rarity44.
The warmer weather also allowed significant new colonisation. For four hundred years, from 800 to 1200 approximately, Vikings or Northmen from Scandinavia roamed European waterways, terrorising coastal areas. By 874 they had settled permanently in Iceland45.
Erik the Red was a violent and quarrelsome man who had to leave his home in south-western Norway late in the tenth century “because of some killings” and sailed to Iceland where he married a local woman. Two more violent quarrels resulted in his banishment.
From Iceland twenty-five ships of colonists sailed with him and fourteen arrived to establish the Eastern Settlement in south-west Greenland. Another group went further north to found the Western Settlement. These remained for nearly 400 years.
A recent study sponsored by Brown University of core measurements taken from two lakes near the Western Settlement throw new light on its collapse in the mid 1300s, while the Eastern Settlement vanished in the first two decades of the 1400s.
The study showed a temperature drop of four degrees Celsius from 1100 to 1180, which almost certainly caused shorter crop-growing seasons and less available food for livestock46.
At least one Viking burial places still lies in the Greenland permafrost and the Medieval Warming there remains as an inconvenient fact47, an interesting backdrop to the foolish and mistaken claim in the newest edition of The Times Atlas of the World, which redefined fifteen per cent of Greenland’s ice-covered land as “green and ice-free”48.
We also find milder and more pleasant examples of this warm time. Aelfric, a noted Anglo-Saxon preacher who died in 1010, was Abbot of Eynsham near Oxford. In a homily for the first Sunday after Easter he remarked in passing that “we often saw silk worms” that “throughout the world make silk for all fine cloth.” Obviously it was consistently warm enough then, even in Oxford, for a continuing silk-worm life cycle49.
The cold-sensitive beetle Heterogaster urticae was found in York in the High Middle Ages, but today is found only in the south of England50.
In 1135 the water flow in the Danube was so low that people could cross it on foot. Somewhat earlier the Rhine had suffered the same fate. Around the middle of the Little Ice Age, the year 1540 was the warmest and driest for the millennium in Central Europe. Once again the Rhine dried up. We can only imagine the excitement such events would provoke today51.
Western Europe thrived in the Medieval Warming which saw the beginning of our great universities and the construction of many magnificent Gothic cathedrals.
As the evidence for the Medieval Warming has increased, some of the exponents of AGW have conceded its existence in the northern hemisphere but contested the claim that it extended south, despite the previously mentioned Idso database52.
Once again Brian Fagan has collected the scientific evidence from deep-sea cores, pollen samples, tree-rings and Andean ice cores and conclusively established the reality of an American Medieval Warming dominated by long, catastrophic droughts53.
For ten centuries until 900AD, the Maya flourished in Central America, probably numbering eight to ten million people around 800AD.
Climatologist David Hodell began his research on sedimentary cores from salty Lake Chichancanab in the Yucatan in 1993. Continued work demonstrated a severe drought from 750 to 1025AD, which coincided with the Maya collapse of the southern lowlands.
The second example is Tiwanaku, a state of 50,000 people which flourished for 600 years in the first millennium, and collapsed leaving glorious ruins fifteen kilometres east of Lake Titicaca in Bolivia.
A fine-grained ice core from the Quelccaya ice cap high in the Andes, 200 kilometres away, show a dry period from 1040-1450. By 1150 the people had dispersed into small villages54.
The destruction of two civilizations after terrible droughts from the global warming of the Middle Ages overshadows even Erik the Red’s colonial exploits, to say nothing of the Abbot of Eynsham’s silk worms.
The continuing pre-eminence of the Western world depends on the continuing creative interaction which fuelled the rise; the life-generating friction between the different forces symbolized by Athens, Rome (secular in this case), and Jerusalem.
Whatever our political masters might decide at this high tide of Western indebtedness, they are increasingly unlikely, because of popular pressure, to impose new financial burdens on their populations in the hope of curbing the rise of global temperatures, except perhaps in Australia, which has two per cent of the world’s industrial capacity and only 1.2 per cent of its CO2 emissions, while continuing to sell coal and iron worth billions of dollars to Asia.
The debates about anthropogenic global warming can only be conducted by the accurate recognition and interpretation of scientific evidence. The evidence of historians is also vital because this is not simply a mathematical problem, not “pure” science.
Extreme-weather events are to be expected, but are unexpected in every period. No one towards the end of the Medieval Warming in Europe expected the rapid descent into the cold and wet of the Little Ice Age, for example, or the freezing gales, winds and heavy rains, that produced the short summers and the terrible developing famines of 1315-20. Surprises such as these will continue into the future.
For this reason (among others) I support the recommendation of Bjorn Lomborg55 and Bob Carter56 that, rather than spending money on meeting the Kyoto Protocol which would have produced an indiscernible effect on temperature rise, money should be used to raise living standards and reduce vulnerability to catastrophes and climate change (in whatever direction), so helping people to cope better with future challenges. We need to be able to afford to provide the Noahs of the future with the best arks science and technology can provide.
In essence, this is the moral dimension to this issue. The cost of attempts to make global warming go away will be very heavy. They may be levied initially on “the big polluters” but they will eventually trickle down to the end-users. Efforts to offset the effects on the vulnerable are well intentioned but history tells us they can only ever be partially successful.
Will the costs and the disruption be justified by the benefits? Before we can give an answer, there are some other, scientific and economic, questions that need to be addressed by governments and those advising them. As a layman, in both fields, I do not pretend to have clear answers but some others in the debate appear to be ignoring the questions and relying more on assumptions.
What are the questions? They have to do with the validity of the assumptions, and therefore the conclusions, of the IPCC and, importantly, the relationship of costs and benefits in both monetary and human terms. In other words, we must be sure the solutions being proposed are valid, the benefits are real and the end result justifies the impositions on the community, particularly the most vulnerable. You will gather that I have concerns on all three fronts.
Sometimes the very learned and clever can be brilliantly foolish, especially when seized by an apparently good cause. My request is for common sense and more, not less; what the medievals, following Aristotle, called prudence, one of the four cardinal virtues: the “recta ratio agibilium” or right reason in doing things. We might call this a cost-benefit analysis, where costs and benefits are defined financially and morally or humanly and their level of probability is carefully estimated. Are there any long term benefits from the schemes to combat global warming, apart from extra tax revenues for governments and income for those devising and implementing the schemes? Will the burdens be shared generally, or fall mainly on the shoulders of the battlers, the poor? Another useful Latin maxim is “in dubio non agitur“: don’t act when in doubt. There is no precautionary principle, only the criteria for assessing what actions are prudent.
When Galileo was placed under house arrest primarily because of his claim that the earth moved around the sun, he is said to have muttered “Eppur’ si muove“; and yet it moves.
As for Galileo so for us, the appeal must be to the evidence, not to any consensus, whatever the levels of confusion or self-interested coercion. First of all we need adequate scientific explanations as a basis for our economic estimates. We also need history, philosophy, even theology and many will use, perhaps create, mythologies. But most importantly we need to distinguish which is which.