The Age of Global Warming: A History (18 page)

Thatcher concluded her speech by referring to one of the most famous events in the Royal Society’s history, when in 1919 Arthur Eddington displayed the photographic plates taken during the total eclipse of the sun earlier that year. The eclipse enabled Eddington to record whether light from distant stars was bent by the sun’s gravity and verify a prediction of Einstein’s theory of relativity. 

Whitehead witnessed Eddington’s demonstration. The scene, tense as a Greek drama, he wrote, was played out beneath the portrait of Isaac Newton, the Society’s twelfth president, ‘to remind us that the greatest of scientific generalisations was now, after more than two centuries, to receive its first modification’.
[26]
In Vienna, reports of it thrilled the seventeen-year-old Karl Popper. What particularly impressed Popper was the risk implied by Einstein’s theory, that light from distant stars would be deflected by the Sun’s mass, because it could be subjected to a definitive test:  ‘If observation shows that the predicted effect is definitely absent, then the theory is simply refuted. The theory is
incompatible with certain possible results of observation
– in fact with results which everybody before Einstein would have expected.’
[27]

These considerations led Popper to argue that the criterion for assessing the scientific status of a theory should be its capacity to generate predictions that could, in principle, be refuted by empirical evidence, what Popper called its falsifiability, or refutability, or testability.
[28]
Every ‘good’ scientific theory is a prohibition. The more a theory forbids, the better it is. Scientists should therefore devise tests designed to yield evidence that the theory prohibits, rather than search for what the theory confirms. If we look for them, Popper argued, it is easy to find confirmations for nearly every theory. ‘Only a theory which asserts or implies that certain conceivable events will not, in fact, happen is testable,’ Popper explained in a lecture in 1963. ‘The test consists in trying to bring about, with all the means we can muster, precisely these events which the theory tells us cannot occur.’
[29]

In 1988, proponents of global warming did not provide a similar black and white predictive test of the key proposition of global warming: the degree of warming with increasing levels of carbon dioxide in the atmosphere. It is therefore incapable of being falsified. The issue is not the capacity of carbon dioxide to absorb radiation in a test tube, which had first been demonstrated by John Tyndall in 1859, but the effect of increased levels of atmospheric carbon dioxide and other greenhouse gases on the temperature of the atmosphere. An answer can only be derived from empirical observation. 

Revelle and Suess’s characterisation of mankind carrying out a large-scale geophysical experiment, further illustrates global warming’s weakness as a scientific statement and its strength as a political idea. While prejudging the results of an experiment constitutes bad science, the proposition simultaneously generates powerful calls to halt the experiment before it is concluded. Yet questioning the science would inevitably be seen as weakening the political will to act. It created a symbiotic dependence between science and politics that marks 1988 as a turning point in the history of science and the start of a new chapter in the affairs of mankind.

*  When asked in 2010, former secretary of state George Shultz had no specific recollection of discussions on the Brundtland Report or sustainable development (email to author from Susan Schendel, 14
th
October 2010).

12

Two Scientists

There’s no doubt that any man with complete conviction, particularly who’s an expert, is bound to shake anybody who’s got an open mind. That’s the advantage of having a closed mind.

John F. Kennedy
[1]

Science is one of the very few human activities – perhaps the only one – in which errors are systematically criticised and fairly often, in time, corrected.

Karl Popper
[2]

We cannot know how the future will judge the era of global warming that dawned in 1988. We can listen to the voices from the past. The past can provide perspective. History is fluid, events are contingent, seemingly immutable categories that condition thought and action, evolve over time. Many scientists were environmentalists, subscribing to the tenets of environmentalism. Until the advent of global warming, environmentalism could not claim the support of science. 

Before science became set in the concrete of the present, it is timely to introduce two scientists from the past and preview the terrain across which the science unfolded. The first died well before the global warming era and the main body of professional work of the second also took place before then. Neither, therefore, had any affiliation in the disputes about global warming. 

Percy W. Bridgman was a Harvard physicist, winner of the 1946 Nobel Prize for his discoveries in the field of high pressure physics and one of nine signatories of Albert Einstein and Bertrand Russell’s 1955 manifesto on nuclear disarmament. Bridgman’s is a voice that speaks of the critical importance of verification in science and of the inherent problem in talking about the future, which for him assumed an entirely different character from studying the past. Writing of the ‘inscrutable character of the future’, Bridgman thought that statements about the future belonged to the category of pseudo-statements.

I personally do not think that one should speak of making statements about the future. For me, a statement implies the possibility of verifying its truth, and the truth of a statement about the future cannot be verified.
[3]
 

Why is verification important? ‘Where there is no possibility of verification there can be no error, and “truth” becomes meaningless.’
[4]
Bridgman accorded greater confidence to the astronomer than to the man in the street to a verification of whether the sun had risen that day. If it had not, it would have involved suspension of the laws of mechanics which the astronomer had observed were manifest in every moving thing.
[5]

Global warming, of course, involves projecting increased levels of atmospheric carbon dioxide and other greenhouse gases into the inscrutability of the future. However it is not possible to determine global temperature in advance, solely by reference to the laws of physics and chemistry. The value of the climate sensitivity of carbon dioxide, the impact on average global temperatures from a doubling of the concentration of carbon dioxide, is unknown. 

Though an upper limit can be inferred from global temperatures not increasing dramatically since the Industrial Revolution, there is no lower limit above zero.
*
Making an assumption more precise than this amounts to educated guesswork about what the forecaster believes
should
happen. If someone says, ‘It will rain tomorrow,’ what they mean is, ‘I expect it will rain tomorrow.’ Our predictions embody our expectations. As Bridgman put it, ‘to “correctly-predict” is a verb which has only a past tense.’
[6]
Thus predictions of future temperature increases tell us less about whether the planet was heading for a climatic fever than the beliefs of the people making them.

Our second scientist was Britain’s first leading climate scientist. Hubert Lamb was a friend of Guy Stewart Callendar. He had a long career in the Meteorological Office before being appointed founding director of the Climatic Research Unit in 1972 at what later became the University of East Anglia. Delving into weather records and other historical evidence such as diaries, pictures and population records, Lamb used his knowledge of weather patterns to argue that climate variability was an important but neglected factor in explaining the development and decline of various human societies. 

In his last book, published in 1982, Lamb repeatedly used terms that no climate scientist would risk today. Warmer climates are genial, writing of the Medieval Warm Period, ‘the genial climate of the high Middle Ages which coincided with the twelfth- and thirteenth-century climax of cultural development.’
[7]
The cooling trend of the fourteenth century is a ‘climatic deterioration’.
[8]
His research into that cooling (a factor he thought behind recurrence of the Black Death in Europe) led Lamb to be worried by the post-Second World War cooling trend.
[9]
1965 had been the year which halted the long recession of many Alpine glaciers and saw the return of Arctic sea ice around Iceland.
[10]
The cooling trend in the northern hemisphere reversed an earlier upward trend, which had led Callendar to doubt the Callendar Effect, as global warming was known in those days. Lamb acknowledged that some mild winters in the 1970s had ‘caused judgement to hesitate and produced the impression that the spate of writings in the 1960s about climatic change had overstressed the subject’, adding: ‘That was before the winters of record severity in parts of North America and Europe in the later 1970s.’
[11]
  

Lamb therefore assessed the growing belief in anthropogenic global warming against his deep immersion in meteorological history and of post-war cooling. Claims of a warming of between two and eleven [!] degrees centigrade by 2100 were, he wrote carefully, ‘an opinion, seemingly founded on firm scientific knowledge, which has to be taken seriously, even though we may notice some grounds for doubt and scepticism’.
[12]
One cause of Lamb’s scepticism was his observation that the World Meteorological Organisation and other modellers assumed a range for natural fluctuation of plus or minus one degree, later reduced by the IPCC to as little as plus or minus half a degree. Lamb understood probably better than anyone that natural variations could greatly exceed the limited ranges assumed by later climate modellers.

It is only by assuming a small range of natural variation that modellers could project that warming caused by greenhouse gas emissions will ‘swamp’ all other elements of natural variation so the global warming ‘signal’ can emerge from the background ‘noise’. Lamb responded

There is a fallacy in this part of the case since it is impossible to define a figure for the range of natural variation of climate which is meaningful in this connection. The record of prevailing temperatures, whether over the past few centuries or over the much longer-term record of ice ages and interglacial periods, shows that the range of variation is itself subject to variation.
[13]

To establish the amplitude of natural climate variability requires analysis of the climate record of past centuries and millennia. The instrumental record does not stretch sufficiently far – the oldest, the Central England Temperature record, goes back to 1659 on a monthly basis and to 1772 on a daily one. Creating a temperature record going back to the beginning of the current inter-glacial period over ten thousand years ago depends on the use of controversial proxy data. These include evidence from lake sediment, ice cores, pollen records and tree ring and coral ring studies.

What the bounds of natural variability might be – whether it is plus or minus one or half a degree – alters the significance of the estimated 0.6 degree (plus or minus 0.2) rise over the course of the twentieth century. If the rise falls within the bounds of natural variability, there is no need for man-made global warming to explain it. Having a version of the climatic past that showed a narrow amplitude of natural fluctuation was therefore essential in prosecuting the case for global warming.

There was a second reason. Part of the idea of global warming is that elevated temperatures are harmful. This invites comparison with previous climatic episodes. Are current temperatures unprecedented in human history? If not, how badly did human societies and ecosystems fare during previous warm periods? On the other hand, might such episodes, far from being harmful, have been benign and, to borrow Lamb’s term, genial? 

After 1988, climate scientists and the IPCC expended great effort on reconstructing a global temperature record. In doing so, climate scientists descended from the impregnable heights of unverifiable assertion about the future to the arena of evidence of the past and the requirements of reproducibility and verifiability. ‘Your statement that you have verified something is indifferent to me unless I believe that I could make the verification also,’ was the way Bridgman described it.
[14]
It was on this field that the science of global warming suffered its first defeat, a strategic reversal from which it has not yet recovered.

A dramatic new version of the temperature record over the last thousand years was presented in 2001 in the IPCC’s Third Assessment Report. The message appeared compelling: 1998 was the warmest year in the warmest decade in the last one thousand years. The Hockey Stick graph, which told a story of a declining temperature trend in the northern hemisphere for nine hundred years, then an abrupt uptick at the beginning of the twentieth century, could not meet a verification standard such as that required by Bridgman. Despite considerable obstruction, it was shown by independent researchers, notably Canadian mining analyst Steve McIntyre and his economist colleague Ross McKitrick, to be a statistical contrivance.

The counter-attack defending the Hockey Stick demonstrated even more clearly how rapidly scientific standards have changed. It was now argued that the universal principle of verification should be restricted to a select group of experts. Only papers in peer-reviewed literature that supported their views were to be considered legitimate in settling the dispute. 

Popper issued a stark warning against such thinking with implications that go to the fundamental basis of Western civilisation.

An open society (that is, a society based on the idea of not merely tolerating dissenting opinions but respecting them) and a democracy (that is, a form of government devoted to the protection of an open society) cannot flourish if science becomes the exclusive possession of a closed group of specialists.
[15]

A further danger with having a closed group is in reinforcing the natural tendency of the human mind to fit facts into preconceived theory. To explain why planets and stars were in positions they shouldn’t according to the Ptolemaic system of the Earth being at the centre of the universe, medieval astronomers added geometrically complex and implausible epicycles. Adding ‘epicycles’ has come to be synonymous with adopting stratagems to avoid questioning the basic premise of a scientific proposition.

The hypothesis of dangerous global warming is sufficiently accommodating to be consistent with a wide spectrum of outcomes, even if these were not specifically predicted beforehand. The observed pause in the warming trend in the first decade of the twenty-first century was not predicted by climate scientists. After the event, they explained it away by invoking the Pacific Decadal Oscillation and not questioning the premise of their models. 

1988 came at the end of a first decade of warming, reversing the previous twenty-year trend of declining temperatures. This decline, which Lamb had thought indicated a long-term cooling trend, has since been interpreted as masking the rise that would have happened were it not for aerosols – microscopic particles formed in the atmosphere from coal-fired power station emissions – that reflect back the sun’s incoming radiation.
*
  As with the post-1998 cessation of warming, this rationalisation is of the same type as that applied by medieval astronomers in invoking their epicycles. ‘The physicist has, and the rest of us should have a temperamental aversion to
ad hoc
constructions in his theorising,’ Bridgman cautioned. For the use of ad hoc argument means there is no second method of arriving at a theory’s terminus, and therefore, Bridgman argued, ‘no method of verifying that the construction corresponds to anything “real”’.
[16]

Instead of seeking to meet Popper’s criterion of falsifiability, the activities of climate scientists conform to an earlier injunction pre-dating the Scientific Revolution: ‘Seek, and ye shall find.’ Climate scientists have followed this teaching from the Sermon on the Mount in their search for confirmatory evidence of global warming in shrinking ice caps, retreating glaciers and inferring past temperatures from tree rings.

The lack of a falsifiability test led scientists and governments into putting their faith in the existence of a scientific consensus as the guide to scientific truth. This too, according to Bridgman, is problematic. Consensus is one of the methods used to weed out individual error, but its role was strictly limited. He specifically rejected the notion of defining science as the consensus of all competent observers. Relying on verification by ‘competent persons’ during any epoch meant having a selection of people who had been subject to definite preconditioning.
[17]
It might, Bridgman thought, signify little more than the discovery that under similar conditions, different human animals react the same way

merely because there are so many common features in the construction of all human animals. Verification by consensus is always to be accepted with extreme reservation.
[18]

In contrast to Bridgman’s caution, consensus-building is at the heart of what the IPCC does. It rests on a highly questionable claim: the subjective opinions of individual scientists can be transmuted into scientific knowledge through the process of being formed into an agreed judgement. In his 2009 book
Why We Disagree About Climate Change
, climate scientist and IPCC author Mike Hulme cited the IPCC’s expressions of increasing confidence in attributing rising temperatures to human activities as how consensus works to establish scientific knowledge; from the caution of its First Assessment Report in 1990 to what Hulme called the bullishness of its Fourth Assessment Report in 2007. According to Hulme,

at each stage of the process, substantial judgment on the part of the scientist(s) is required; a judgement formed through dialogue, dispute and compromise rather than through detached and disinterested truth-seeking.
[19]

There was little alternative to relying on such procedures, Hulme argued. ‘In complex and uncertain areas of knowledge “objective methods” alone are rarely adequate to establish what is known.’
[20]

The purpose of consensus is to gain agreement with a view to taking collective action. Here, an altogether larger claim is being made: consensus can transform belief into knowledge. This requires us to accept that there is no fundamental difference between belief and knowledge, so long as there is collective agreement on it by those whose opinions count – the experts who don the mantle of scientific authority. In this way today’s scientists have become modern day alchemists transforming the lead of subjective belief into the gold of objective knowledge.

Such a claim has profound implications for the nature of science itself. It permits scientists to slip the bounds of what had traditionally been understood as science into pseudo-science, to adopt Popper’s term, and into the realm of futurology. For sure, eminent scientists can make more of an impact on the popular imagination with their essays in futurology than with their scientific research. In 2006 the physicist Stephen Hawking made headlines with his prediction that humans would have to leave Earth to avoid the risk of the species being wiped out by an asteroid or a nuclear disaster.
[21]
In 2003, Britain’s Astronomer Royal and future president of the Royal Society Martin Rees wrote a book,
Our Final Century
(
Our Final Hour
in the American market), which estimated that mankind had only a fifty per cent chance of surviving the century thanks to threats even more dangerous than global warming.

The historian must accept a definition of science as being what scientists do. However, the historian can make two claims. The first is that the predictive record of scientists on the future of mankind is rather worse than a random selection of people off the street. The scientists who put their names to the
Blueprint for Survival
in 1972 – predicting civilisation would come to an end in the lifetimes of people then living – proved spectacularly poor guides to the future. The actions of ordinary people who maintained their commitment to the future, the most important one being the decision to have children, have been vindicated. 

Second, the nature and purpose of science has undergone profound change in recent decades. Until around the middle of the last century, science was about making discoveries and solving problems by refining and modifying theories so that they better conformed to what had been found in laboratory experiments and seen through telescopes. The purpose of these activities was the advancement of scientific knowledge.