Global warming – where’s the consensus?

• European politicians, environmentalists and the media are unable to resist the temptation to link contemporary extremes of weather to global warming, even though there is little or no evidence for this. And they know it.
• A greater awareness of the range of variables influencing climate change and the potential impact on humans is making for a more interesting and realistic scientific debate. But this is rarely reflected in the public discussion. Instead, worst-case scenarios are commonly presented as fact.
• A rapid warming, of 3.5 degrees centigrade or more within the next century, would threaten significant changes. But would a more modest warming pose such a threat? There is a sound scientific basis, in both theoretical modelling and the study of past climates, for the view that a warmer world might be a better place for humans.
• Environmentalists, policy makers and some scientists might prefer comfortable claims such as ‘science tells us’ we must do x, y or z. But given a range of uncertainties, cultural and social expectations have as much – if not more – bearing on the way we feel we should act as does scientific data.

George W Bush’s apparent questioning of the seriousness of the threat posed by man-made global warming, and the soundness of the science upon which global warming projections are based, has understandably irritated many scientists.

But before they heap even more opprobrium on the oilman from Texas, scientists should take the time to put their own house in order. For they have often left unchallenged a simplistic and fearful public and policy debate on the issue of global warming – and some even have colluded in this debate, in which worst-case scenarios are presented as projections, and possibilities as certainties.

In rejecting the deal to reduce the output of greenhouse gases that was agreed at Kyoto in 1997, Bush highlighted the energy crisis that has caused power cuts in one of the most technically advanced states in the world: ‘At a time when California has already experienced energy shortages, and other Western states are worried about price and availability of energy this summer, we must be careful not to take actions that could harm consumers.’

This was all a bit too much for Donald Kennedy, the [Californian] editor-in-chief of the prestigious journal Science. ‘[It was] bad enough that we had our notorious deregulation fiasco, abetted by industry advocates and accomplished in governor Pete Wilson’s term; now, just when our electric bills have tripled, we get used as an excuse for another unfortunate move!,’ he wrote in March. ‘It’s almost enough to make us pretend we’re from somewhere else.’

In Kennedy’s view the scientific consensus around global warming is so strong that it ‘leaves little room for the defensive assertions that keep emerging from the cleverly labelled industrial consortium called the Global Climate Coalition and from a shrinking coterie of scientific skeptics’. Indeed, ‘consensus as strong as the one that has developed around this topic is rare in science’ (1).

For Kennedy, the issue is a clear case of oil interests versus science. He would have a point if all that mattered were the question ‘Do you believe in the theory of man-made global warming?’. But the issues are messier than that; and on most of the interesting questions, those shouting at Bush need to face some uncomfortable truths about the public discussion of climate change.

European politicians, environmentalists and the media are unable to resist the temptation to link contemporary extremes of weather to global warming, even though there is little or no evidence for this. And they know it.

A very wet autumn throughout Britain last year led the BBC’s flagship documentary programme Panorama to declare that Britain was ‘at war’ with unfamiliar weather. In his big pre-election speech on the environment on 6 March 2001, UK prime minister Tony Blair told us that heavy snowfall in Scotland had something to do with global warming as well.

According to Christian Aid, global warming was responsible for the most severe drought in India for 100 years in the summer of 2000. ‘One hundred million people in India’, the charity asserted, ‘are paying the price of climate change’.
And CNN told the world in February 2001 that the latest research from the UN Intergovernmental Panel on Climate Change (IPCC) warns of ‘climate destruction’; ‘enormous loss of both human and animal life due to greater risk from diseases like malaria’; and more ‘cyclones, floods and droughts and massive displacement of populations in worst-affected areas’.

All these changes threaten social dislocation, hitting the poorest and most vulnerable hardest. We are also warned of knock-on social effects. Influential sociologist Ulrich Beck tells us that the international insurance trade is feeling the ‘devastating consequences of the greenhouse effect’. The result, he argues, is that ‘insurance companies drop risks’ (2).

Beck is right – to the extent that the insurance industry is certainly talking up the threat of global warming. Gerhard Berz of Munich Re, the world’s largest reinsurer, believes that ‘there is reason to fear that climatic change will lead to natural catastrophes of hitherto unknown force and frequency’, leading to worldwide losses ‘totalling many hundreds of billions of dollars per year’.

But this public consensus – that adverse events are already upon us with much worse to come – rests on very shaky scientific foundations, as the chief executive of the UK’s Met Office felt compelled to tell The Times after the flood of speeches by Blair, deputy prime minister John Prescott and environment minister Michael Meacher (3). On many issues, most scientists introduce numerous qualifiers. Regarding some key claims, many scientists flatly contradict the public consensus. And while it clearly believes that global warming is a serious threat, the IPCC cannot be entirely blamed for CNN’s alarmist coverage, at least as much as their most recent official report is concerned.

Extreme events are easy to find once you start looking for them. Most weeks something really unusual usually occurs somewhere (4). Tony Blair’s statement that the heaviest snowfall in the Scottish Borders since 1947 was peculiar smacked of not really trying.

Are any of these extremes indicative of anything more than normal variation? You might be surprised to hear that the IPCC does not generally think so. On two key global issues, storm activity and drought, it says observed variation shows ‘no significant trends evident over the last century’, with what variation there is being dominated by ‘interdecadal and multidecadal climate variability’ (5).

Given this, it shouldn’t be surprising that those who have studied the matter do not believe the modest global warming we have so far experienced has had any real bearing on the rapid rise in insurance claims over the past few decades. In a survey of climate extremes in Science, David Easterling and his colleagues argued that ‘most of the increase has been due to societal shifts and not to major increases in weather extremes’.

The important ‘societal shifts’ in the US context are demographic movements to more vulnerable locations and the growth of wealth. Were these to continue and be combined with more climate extremes in the future, this could ‘greatly exacerbate the loss problem’ (6). But what is the likelihood of this happening? And what are the possible impacts of change on developing countries?

A greater awareness of the range of variables influencing climate change, and the potential impact on humans, is making for a more interesting and realistic scientific debate. Unfortunately this is rarely reflected in the public discussion. Instead, worst-case scenarios are commonly presented as fact. Part of the blame for this must be placed on politicians and some of the media. However, official bodies such as the IPCC are far from innocent.

The IPCC is quite tentative in its projections for an increase in extreme events and detrimental human consequences in the upcoming 100 years. Much has been made of the fact that, in its most recent assessment, the IPCC is more uncertain than it was five or six years ago about the possible scale of future warming. Some skeptics have leapt on this in order to rubbish the science. But that is to misunderstand what is going on.

The greater range of possibilities projected, now running from 1.4 degrees centigrade to 5.8 degrees centigrade over the next 100 years, is a consequence of a greater awareness of the many influences at play, both physical and social. Some of this uncertainty may be reduced in time by a further refinement of the models, and the contribution of a wider range of scientists. But much will remain-the sheer complexity of the physical interactions involved, and the near impossibility of predicting patterns of social and technological development (and hence the output of the all-important gases and particles) will see to that.

Less has been made of the distinction the IPCC draws in its reports between what it calls simple and complex extreme events, and in particular the fact that the IPCC is much more confident in its predictions regarding simple events than regarding complex events.

The IPCC is very confident that the earth as a whole will warm up over the coming century, even if they are unsure by how much. As a consequence, we can expect more days of extreme heat and fewer of extreme cold globally. We can also expect more heavy precipitation resulting from a moister atmosphere. These are examples of simple extreme events. In general, the IPCC is much less confident regarding complex extreme events, such as storms and El-Niño-like phenomena, or something involving a range of human variables as well, such as disease spread. Importantly, these are the kinds of extremes that matter most to human wellbeing.

The 1992 UN Framework Convention on Climate Change (UNFCCC), signed at the Rio ‘Earth Summit’, states: ‘The parties should take precautionary measures to anticipate, prevent or minimise the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures.’

Although the IPCC is formally independent of the UNFCCC, being charged with simply providing scientific assessments, in practice (especially through the summaries presented to policy makers) it works within this precautionary framework. As a result, the IPCC has introduced an assumption of harm into its policy recommendations.

Human societies have the potential to develop and manage environmental change. As regards human wellbeing, the level of development is by far the most important causal factor in determining the impact of environmental change. One consequence of the assumption of harm is that the public discussion often ignores this. This is reinforced by the cultural framework in which climate change is discussed, which tends to see economic and technological development as part of the problem, rather than the solution.

Take, for example, CNN’s warning of ‘enormous loss of both human and animal life due to greater risk from diseases like malaria’. As Rogers and Randolph point out, such projections are based on ‘biological transmission models driven principally by temperature’ (7), while in reality many other factors matter, including the interactions of parasite and host in a changed climate.

Most importantly, aspects of the human environment, such as the level of sanitation and other basic factors affecting health and parasite spread, are the key determinants. Historically, regions of Italy have been plagued by malaria; its relative absence now owes much more to social development than to changed climate. From 1980 to 1996 there were more than 50,000 confirmed cases of dengue in the three Mexican states that border the Rio Grande; across the river in Texas there were fewer than 100 cases.

It might seem fanciful (or ‘Western-centric’) to imagine that Mexico will suddenly resemble Bush’s home state. And it would be if we were talking about changes required within a few years. But over a time-span of decades, even centuries, it is rather depressing to think that countries such as Mexico will not advance significantly. Interestingly, projecting a simple continuation of existing patterns of social development, Rogers and Randolph predict ‘remarkably few changes’ in the prevalence of such diseases compared to the present, ‘even under the most extreme scenarios’.

In the longer term, it is a worthwhile ambition to understand and manage, perhaps minimise, climate change. Tony Blair’s dream of a ‘green industrial revolution’ that is high on technology and low on greenhouse gas emissions might yet catch on in Texas as well as the Netherlands. Certainly, if this possibility becomes a reality, we might expect US governments and everybody else to start taking more serious measures to cut greenhouse gas emissions.

But until they see the hi-tech, developing countries would be wise to prefer development to low emissions. It will give them the flexibility to respond to potentially damaging changes, if and when they occur.

That ‘if’ is something we should keep hold of. And similarly, the most basic assumption of the UN convention on climate change – that ‘parties should take precautionary measures to anticipate, prevent or minimise the causes of climate change’ – should not be accepted at face value. For there is a sound scientific basis, in both theoretical modelling and the study of past climates, for the view that a warmer world might be a better place for humans.

A warmer world could just as easily be less severely affected by extreme events than more so. One of the USA’s most intelligent skeptics of received wisdom on the issue, Patrick Michaels, points out in his provocative book The Satanic Gases that warming will not be evenly spread, but will rather occur most noticeably in the very cold regions in the dead of winter. What, he dryly asks, ‘is so bad about this type of warming?’.

Greater warming in the polar regions might have benefits globally: the future contrast between the polar latitudes and the tropics should lessen, particularly in winter, ‘producing a weaker jet stream, a more contracted vortex, with fewer and/or less powerful cyclones. In short, the future atmospheric circulation should be less ‘winterlike’, with fewer intense storms’ (8).

Deep ice-core records illuminating conditions in warmer times support Michaels’ suggestion. Quite likely, historical evidence also suggests, a warmer world would be a more fertile one too. Between 6000 and 7000 years ago, during the mid-Holocene thermal optimum, temperatures were two to three degrees centigrade warmer than today. Net precipitation was nine percent higher, and the Sahara desert effectively did not exist – in its place was savannah hospitable to life (9).

There is a reasonably strong scientific consensus that a rapid warming, of 3.5 degrees centigrade or more within the short time-span of the next century, would threaten significant changes affecting both the natural world and human life. But whether a more modest warming would pose such a threat is far from clear.

Environmentalists, policy makers and some scientists might prefer comfortable claims such as ‘science tells us’ we must do x, y or z. But the truth is that, given a range of uncertainties, cultural and social expectations have as much – if not more – bearing upon the way we feel we should act as does scientific data.

In their famous work Risk and Culture, Mary Douglas and Aaron Wildavsky argued: ‘In the [nineteenth] century, prevailing opinion held that the future would have better solutions for its problems than the present generation could devise. They rejected “overconsuming safety” in favour of allowing the future to decide for itself’ (10). Bereft of that nineteenth-century confidence in the future we flee from uncertainty and embrace such ‘overconsuming safety’. As the Conservative John Gummer hysterically put it: ‘We can’t take risks with our children’s future and expect something good to turn up. We need to act now.’

But what happens when that felt need to ‘act now’ crashes into the enormous reality check that 60, 70, or even 90 percent reductions are needed in the output of greenhouse gases to make a significant difference? One possible reaction, of course, is to wait, allow better technologies to develop organically rather than forcing the pace, while gathering more data.

In effect this is, in large part, what is happening. It is just that nobody dares make a virtue of it. Instead, such drastic reductions in the output of greenhouse gases are seriously proposed, as for example by the UK House of Commons Science and Technology Committee, which chastises governments for not beating us all about the head hard enough on the issue (11).

This raises the question: has the fearful interpretation of global warming gathered enough momentum to force the pace, even at an economic price to Western economies, or will realpolitik win the day? We should have a better idea soon.

John Gillott is coauthor of Science and the Retreat from Reason, Merlin Press 1995. Buy this book at Amazon (UK) or Amazon (USA).

(1) ‘An unfortunate U-turn on carbon’, D Kennedy, Science 291 (2001), p2515

(2) World Risk Society, Ulrich Beck, Cambridge: Polity 1999, p159. Buy this book from Amazon (UK) or Amazon (USA)

(3) All change over the climate, The Times 16 April 2001

(4) Global Climate Prediction Center

(5) ‘Summary for Policymakers: Climate Change 2001: Impacts, Adaptation, and Vulnerability’, IPCC 2001. Available from the IPCC website

(6) ‘Climate extremes: observations, modelling, and impacts’, D Easterling et al (2000), Science, 289, p2072

(7) ‘The global spread of malaria in a future, warmer world’, R Rogers and S Randolph (2000), Science, 289, p1763

(8) The Satanic Gases, PJ Michaels and RC Balling, Washington: Cato 2000, p91; p149. Buy this book from Amazon (UK) or Amazon (USA)

(9) Wouldn’t a bit of global warming be a good thing?, Peter Sammonds, LM 106, December-January 1998

(10) Risk and Culture M Douglas and A Wildavsky, Berkeley: University of California Press 1982, p23. Buy this book from Amazon (UK) or Amazon (USA)

(11) ‘Scientific Advisory System: Scientific Advice on Climate Change’, House of Commons Science and Technology Committee. London: HMSO 2001, pxvi; p48