[31] Paul Lewis, ‘Thatcher urges pact on climate’ in the New York Times, 9th November 1989.
[32] Note by Robert E. Grady, 11th November 1989, ‘White House comment on Thatcher’s UN speech (Bush “could easily have given it”)’, accessed via Thatcher Foundation http://www.margaretthatcher.org/document/110772
[33] John Hunt, ‘Market way sought to a greener world’ in the Financial Times, 2nd May 1990.
[34] Michael McCarthy, ‘Whaling batters Norway’s image’ in The Times, 14th May 1990.
[35] William Claiborne, ‘Memo shows Canada supports US resistance to tighter pollution controls’ in the Washington Post, 11th May 1990.
[36] ‘Pollution crackdown pledged Bouchard makes abrupt turnaround on global warming’ in the Toronto Star, 17th May 1990.
[37] UNFCCC figures extracted from Time series http://unfccc.int/ghg_data/ghg_data_unfccc/time_series_annex_i/items/3814.php
[38] Lead article, Financial Times, 18th May 1990.
[39] Michael McCarthy, ‘US fears over cost of global warming’ in The Times, 16th May 1990.
[40] The Bergen Conference and its proposals for addressing climate change, May 1990 http://unfccc.int/resource/ccsites/senegal/fact/fs220.htm
14
Rush to Judgment
There are three roads to ruin; women, gambling and technicians. The most pleasant is with women, the quickest is with gambling, but the surest is with technicians.
President Georges Pompidou
Any remaining doubts must not be allowed to dissuade us from action.
Michel Rocard, 6th November 1990
While governments were engaged in an accelerating round of conferences, scientists were working to meet the deadline for the IPCC’s First Assessment Report ahead of the World Climate Conference in November 1990. As chair, Bolin had to overcome a major disagreement between Working Group I, tasked with summarising scientific knowledge under Sir John Houghton, and Working Group II, led by Soviet academician Yuri Izrael to examine potential impacts of global warming.
One of the Soviet scientists in Working Group II argued that warming might be beneficial at northerly latitudes (an opinion that had been held by Svante Arrhenius and Guy Stewart Callendar in the first half of the twentieth century). Preventative action was therefore not justified. A meeting was held in Leningrad but, according to Bolin, there was still tension.[1] Even within Working Group I, agreement was not always easy.[2]
Bolin had wanted to document and explain reasons for disagreement. ‘I had repeatedly pointed out to the working groups that the goal was not necessarily always to reach an agreement, but rather to point out different views when necessary and to clarify reasons for disagreements when possible, but this was still seldom tried,’ he recalled.[3] Despite Bolin’s encouragement, public airing of disagreements was counter-cultural.
Nonetheless, the First Assessment Report went further in meeting this objective than subsequent ones. It was also more open in highlighting not only uncertainties in the science (one can be uncertain about the particular outcome of tossing a coin, but the parameters of the outcome can be defined with certainty), but also ignorance, especially in the section dealing with past climate variations and change (Section Seven of the Working Group I report). As the IPCC developed, admissions of ignorance gave way to more qualified expressions of uncertainty, often couched in spurious degrees of confidence.
According to the Working Group I Summary for Policy Makers, the observed global mean surface air temperature had increased by between 0.3oC and 0.6oC over the previous hundred years.
The size of this warming is broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability. Thus the observed increase could be largely due to this natural variability; alternatively this variability and other human factors could have offset a still larger human-induced greenhouse warming.[4]
The recent warming was neither unique nor could natural variability be ruled out. Section Seven of Working Group I on past climate variations noted that although the evidence pointed to a real but irregular warming over the last century, ‘a global warming of larger size has almost certainly occurred at least once since the end of the last glaciations without any appreciable increase in greenhouse gases. Because we do not understand the reasons for these past warming events it is not yet possible to attribute a specific proportion of the recent, smaller warming to an increase of greenhouse gases’.[5]
Putting the twentieth-century warming in the context of past climatic changes, the report pointed out that the Little Ice Age involved global climate changes of comparable magnitude to the warming observed over the previous one hundred years to 1990, part of which could reflect cessation of Little Ice Age conditions. ‘The rather rapid changes in global temperature around 1920–1940 are very likely to have had a natural origin,’ the report went on. ‘Thus a better understanding of past variations is essential if we are to estimate reliably the extent to which warming over the last century, and future warming, is the result of greenhouse gases,’ a need that would give rise to the Hockey Stick and its prominence in the 2001 Third Assessment Report.[6]
The crucial section of the entire report was on the detection of the enhanced greenhouse effect (Section Eight of the Working Group I report). Its authors acknowledged that the 0.3oC to 0.6oC observed rise in average global temperatures permitted a number of explanations. If it had been caused by a ‘man-induced’ greenhouse effect, then the implied climate sensitivity of carbon dioxide (the warming resulting from a doubling of carbon dioxide in the atmosphere) would be at the bottom of the range. If a significant fraction of the warming had been due to natural variability, the implied value for the climate sensitivity would be even lower than model predictions. If a larger greenhouse warming had been offset by natural variability or other factors, then the climate sensitivity of carbon dioxide could be at the ‘high end’ of model predictions.[7] Scientists’ inability to reliably detect predicted signals should not be taken to mean that ‘the greenhouse theory is wrong, or that it will not be a serious problem for mankind in the decades ahead’.[8]
Section Eight also carried an implicit rebuke to James Hansen and his claim two years earlier to have detected the greenhouse effect.
Because of the many significant uncertainties and inadequacies in the observational climate record, in our knowledge of the causes of natural climatic variability and in current computer models, scientists working in this field cannot at this point in time make the definitive statement: ‘Yes, we have now seen an enhanced greenhouse effect.’[9]
With the possible exception of an increase in the number of intense showers, there was, the Summary for Policy Makers said, no clear evidence that weather variability would change in the future.[10] Neither was there evidence that tropical storms had increased or any consistent indication that they would be likely to increase in a warmer world.[11]
Nonetheless, belief in anthropogenic global warming shines through the pages of the Working Group I report, especially the twenty-eight-page Summary for Policy Makers. ‘We calculate with confidence,’ the summary claimed, ‘that carbon dioxide has been responsible for over half the enhanced greenhouse effect in the past’.[12] At first glance, it might appear that here the IPCC had nailed its culprit. In actual fact, the claim teeters on the brink of meaninglessness. As the report admitted, scientists were unable to attribute the contribution of the enhanced greenhouse effect to the observed rise in global temperatures over the previous one hundred years. To have said that extra carbon dioxide was responsible for over half of an effect that couldn’t be measured or even detected was the modern equivalent of medieval monks counting angels on pinheads.
Distilled to its essence, the message of the First Assessment Report was that global warmi
ng is happening, even though the evidence remained equivocal. In one of the most significant passages in the report, the IPCC stated: ‘The unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more, when the commitment to future climate change will then be considerably larger than it is today.’[13] Thus for the IPCC, detection of the greenhouse effect was a question of ‘when’ not ‘if’, as Sir John Houghton wrote in the Financial Times. ‘We are sure that human activities are leading to climate change – although we do not claim yet to have detected it.’[14]
The most loaded claim was the report’s call for action. ‘If there are concentration levels that should not be exceeded,’ the Summary for Policy Makers warned, ‘then the earlier emission reductions are made the more effective they are,’ hinting at the possibility of undefined tipping points and climate catastrophism.[15] Yet buried in the body of the report, the IPCC noted growing evidence that worldwide temperatures had been higher than at present, at least in summer, around five to six thousand years ago, although carbon dioxide levels were thought to have been quite similar to the pre-industrial era.[16]
Alarm about global warming depended on a critical but unverifiable assumption: increased levels of carbon dioxide trigger positive feedbacks amplifying the direct warming effect from carbon dioxide. Water vapour plays the central role in assumptions about positive feedbacks. It is a more abundant and powerful greenhouse gas than carbon dioxide (the IPCC estimated that if water vapour were the only greenhouse gas present in the atmosphere, the greenhouse effect would be sixty to seventy per cent of the value of all gases included, but if carbon dioxide alone were present, the corresponding value would be about twenty-five per cent).[17] Without positive feedback from water vapour and other sources, the IPCC estimated a value of +1.2oC for the climate sensitivity of carbon dioxide.
However, the IPCC assumed that the impact of this initial warming is amplified by increasing the concentration of water vapour, raising the initial 1.2oC to 1.9oC.[18] There are many other feedbacks; overall, they might be positive and amplify the direct warming effect of added carbon dioxide, or they might be negative and dampen it. More water vapour might lead to more clouds being formed. ‘Feedback mechanisms related to clouds are extremely complex,’ Working Group I stated. ‘There is no a priori means of determining the sign of cloud feedback.’[19]
Results from computer climate models cited in the 1990 report gave a range of 1.9oC to 5.2oC for the climate sensitivity of carbon dioxide. Taking into account these results together with observational evidence, the IPCC chose a value of 2.5oC as its best estimate, implying that over half the warming effect of carbon dioxide assumed by the IPCC came from positive feedbacks.[20]
The IPCC’s handling of the role of clouds was criticised by Richard Lindzen, professor of meteorology at the Massachusetts Institute of Technology. Without the assumption of an overall positive feedback effect, the IPCC would have assumed a rise closer to 1oC from a doubling of carbon dioxide. If the IPCC and scientific orthodoxy had followed Lindzen, it is safe to say that the post-1988 era would not be an age defined by belief in global warming.
In addition to uncertainty and ignorance over the size and direction of feedbacks, the IPCC made an even more fundamental assumption based – literally – on hope, that, in the words of the IPCC, ‘The climate system is in equilibrium with its forcing.’[21] Making any forecasts of long-term temperature depends on the extent to which this assumption holds. While the assumption is necessary and desirable from the perspective of climate modellers, it does not follow that nature will accommodate it. Although some elements of the climate system were chaotic on a century to millennium timescale, others were stable. ‘That stability,’ the report went on, ‘gives us hope that the response of the atmospheric climate (including the statistics of the chaotic weather systems) to greenhouse forcing will itself be stable and that the interactions between the atmosphere and the other elements of the climate system will also be stable.’[22]
Large-scale features of the world ocean circulation system were deemed to be non-chaotic by the IPCC. ‘The question,’ according to the Working Group I report, ‘is whether the existence of predictability in the ocean component of the Earth’s climate system makes the system predictable as a whole. However this seems to be a reasonable working hypothesis,’ the authors thought.[23] Absence of computing capacity meant that scientists were unable to model the response of the oceans, even though, as the 1990 report said, ‘this is crucial for climate prediction’.[24] It is easy to see why. The entire heat capacity of the atmosphere is equivalent to less than three-metres-depth of water.[25] In the North Atlantic, the heat input carried by the ocean circulation is of similar magnitude to that reaching the ocean surface from the sun.[26]
The sheer length of time for the oceans to respond to a warming atmosphere opened up a huge disconnect between the timescales over which scientists were anticipating global warming and the ‘children and grandchildren’ timescale deployed by politicians to justify action against global warming. According to Working Group I, the global oceans need millennia to reach a new equilibrium, making a couple of generations a rounding error.[27] Even if it were possible to stop all man-made emissions of carbon dioxide, atmospheric concentrations would decline very slowly and would not approach their pre-industrial levels for ‘many hundreds of years. Thus any reductions in emissions will only become fully effective after a time of the order of a century or more’.[28]
With positive feedbacks assumed in the climate models, the IPCC’s business-as-usual scenario of emissions growth predicted a temperature rise of 0.3oC per decade (i.e., in the subsequent one to two decades, the world would get the whole of the 0.7oC temperature rise observed in the twentieth century), resulting in a ‘likely’ rise of 1oC by 2025.[29] By 2009, well past the halfway mark of this thirty-five-year forecast, the temperature had risen by 0.18oC since 1990, or an average of just under 0.1oC per decade.[30] To hit the predicted one-degree rise by 2025, the average global temperature would have to rise at an average rate of 0.5oC per decade for the rest of the period.
Throughout the time when the IPCC report was being prepared, one political leader took a particularly keen interest in the scientists’ progress. Mrs Thatcher asked Houghton for regular updates. The week of 21st May 1990 was particularly intense. On the Monday afternoon, Houghton presented the conclusions of Working Group I report to the prime minister and other ministers in the Cabinet room at Number 10. The next three days, Houghton chaired the plenary of the working group at a hotel in Windsor, on Tuesday and Wednesday returning to Downing Street to help Thatcher with her speech for the opening on Friday of the Hadley Centre to coincide with publication of the IPCC’s assessment report. Houghton was amazed at the prime minister, pencil and erasure in hand, determined to get the science right. She put a lot of her own time into it, Charles Powell, her chief aide, told him.[31]
Your task, she told the Hadley Centre’s director and staff, was no less than ‘to help us safeguard the future of the planet’.[32] Describing the IPCC’s report as of historic significance, she said governments and organisations around the world were ‘going to have to sit up and take notice’. She announced that Britain would set itself the target of cutting projected levels of carbon dioxide emissions by thirty per cent by 2005. Because the projected increases were so high, this meant returning to 1990 levels by that date. Unlike the Dutch and Canadians, the UK beat this target by more than five percentage points, largely thanks to privatising and liberalising the energy market, enabling the market to respond with a dash-to-gas for generating electricity.*
In October 1990, the second World Climate Conference met in Geneva. Unlike the all but forgotten first conference in 1979, it was addressed by six government leaders. Scientists and academics also came to spread the alarm that was not to be found in the IPCC’s equivocation. German meteorologist Harmuth Grassl, a contributor to th
e Working Group I report, said that while scientists were ‘basically here as ruminants, it is very important to get out the main message: that change on earth is now so fast there is no analogy during the last 10,000 years’.[33] It was a claim without any basis in the IPCC report.
Martin Parry, a British geographer and future chair of Working Group II, produced a report claiming that the world could suffer mass starvation and soaring food prices in just forty years.[34] True, there were sharp rises in food prices in the first decade of the twenty-first century. They weren’t caused by rising temperatures but by climate change policies diverting agricultural resources to the production of biofuels, contributing to a wave of food riots in 2008.
The political response was divided between the minority of governments that took seriously the IPCC’s equivocal verdict and those arguing that the need for action overrode it. Despite pressure from the European Community – ‘I hope that Europe’s example will help the task of securing world-wide agreement,’ Thatcher told the conference – the US and the Soviet Union, the world’s two largest carbon dioxide emitters, weren’t budging.[35] Yuri Izrael for the Soviet delegation emphasised the doubt and uncertainty of climate change. More scientific research was needed, Izrael concluded.[36] John Knauss, director of the National Oceanic and Atmospheric Administration, who led the US delegation, said that Washington had refused to set targets because ‘it does not believe in them’, adding, ‘it’s as simple as that. We are not prepared to guarantee our projections’. American officials thought European targets lacked credibility, which they characterised as political goals not easily put into effect.[37]
The Age of Global Warming: A History Page 21