Climate change knows three realities: science reality, which is what working scientists deal with every day; virtual reality, which is the wholly imaginary world inside computer climate models; and public reality, which is the socio-political system within which politicians, business people and the general citizenry work.

The science reality is that climate is a complex, dynamic, natural system that no one wholly comprehends, though many scientists understand different small parts. So far, science provides no unambiguous evidence that dangerous or even measurable human-caused global warming is occurring.

The virtual reality is that computer models predict future climate according to the assumptions that are programmed into them. There is no established Theory of Climate, and therefore the potential output of all realistic computer general circulation models (GCMs) encompasses a range of both future warmings and coolings, the outcome depending upon the way in which they are constructed. Different results can be produced at will simply by adjusting such poorly known parameters as the effects of cloud cover.

The public reality in 2008 is that, driven by strong environmental lobby groups and evangelistic scientists and journalists, there is a widespread but erroneous belief in our society that dangerous global warming is occurring and that it has human causation.

William Kininmonth (“Illusions of Climate Science”, Quadrant, October) has summarised well the nature of the main scientific arguments that relate to human-caused climate change. Therefore, I shall concentrate here a little less on the science, except as background information that relates to how we got to where we are today. My main aim is to explain the need for a proper national climate change policy that relates to real rather than imaginary risk, a policy position that neither the previous nor the present Australian government has achieved. Instead—in response to strong pressure from lobby groups whose main commonality is financial or other self-interest, and a baying media—our present national climate policy is to try to prevent human-caused global warming. This will be a costly, ineffectual and hence futile exercise.

The Realities of Climate Change

Science reality. My reference files categorise climate change into more than 100 sub-discipline areas of relevant knowledge. Like most other climate scientists, I possess deep expertise in at most two or three of these sub-disciplines. As Christopher Essex and Ross McKitrick (in Taken by Storm) have observed:

“Global warming is a topic that sprawls in a thousand directions. There is no such thing as an ‘expert’ on global warming, because no one can master all the relevant subjects. On the subject of climate change everyone is an amateur on many if not most of the relevant topics.”

It is therefore a brave scientist who essays an expert public opinion on the global warming issue, that bravery being always but one step from foolhardiness. As for the many public dignitaries and celebrities whose global warming preachings fill our daily news bulletins, their enthusiasm for a perceived worthy cause greatly exceeds their clarity of thought about climate change science, regarding which they are palpably innocent of knowledge.

In these difficult circumstances of complex science and public ignorance, how is science reality to be judged? This question was first carefully thought through in the late 1980s by the senior bureaucrats and scientists who were involved in the creation of the United Nations Intergovernmental Panel on Climate Change (IPCC). Key players at the time were Bert Bolin (Sweden), John Houghton (UK) and Maurice Strong (Canada), Bolin and Houghton each going on to become Chairman of the IPCC. The declared intention of the IPCC was to provide disinterested summaries of the state of climate science as judged from the published, refereed scientific literature. Henceforward, in the public and political eye, science reality was to be decided by the authority of the IPCC. Accordingly, in four successive Assessment Reports in 1990, 1995, 2001 and 2007, the IPCC has tried to imprint its belief in dangerous human-caused warming on politicians and the public alike, steamrolling relentlessly over the more balanced, non-alarmist views held by thousands of other qualified scientists. Inevitably, and despite the initial good intentions, what started in 1988 as a noble cause had by the time of the fourth Assessment Report (2007) degenerated into a politically-driven science and media circus.

As Essex and McKitrick have accurately written:

“We do not need to guess what is the world view of the IPCC leaders. They do not attempt to hide it. They are committed, heart and soul, to the Doctrine [of human-caused global warming]. They believe it and they are advocates on its behalf. They have assembled a body of evidence that they feel supports it and they travel the world promoting it.

“There would be nothing wrong with this if it were only one half of a larger exercise in adjudication. But governments around the world have made the staggering error of treating the IPCC as if it is the only side we should listen to in the adjudication process. What is worse, when on a regular basis other scientists and scholars stand up and publicly disagree with the IPCC, governments panic because they are afraid the issue will get complicated, and undermine the sense of certainty that justifies their policy choices. So they label alternative views ‘marginal’ and those who hold them ‘dissidents’.

The basic flaw that was incorporated into IPCC methodology from the beginning was the assumption that matters of science can be decided on authority or consensus; in fact, and as Galileo early showed, science as a method of investigating the world is the very antithesis of authority. A scientific truth is so not because the IPCC or an Academy of Science blesses it, or because most people believe it, but because it is formulated as a rigorous hypothesis that has survived testing by many different scientists.

The hypothesis of the IPCC was, and remains, that human greenhouse gas emissions (especially of carbon dioxide) are causing dangerous global warming. The IPCC concentrates its analyses of climate change on only the last few hundred years, and has repeatedly failed to give proper weight to the geological context of the 150-year-long instrumental record. When viewed in historical context, and assessed against empirical data, the greenhouse hypothesis fails. There is no evidence that late-twentieth-century rates of temperature increase were unusually rapid or reached an unnaturally high peak; no human-caused greenhouse signal has been measured or identified despite the expenditure since 1990 of many billions of dollars searching for it; and global temperature, which peaked within the current natural cycle in 1998, has been declining since 2002 despite continuing increases in carbon dioxide emission.

Therefore, science reality in 2008 is that the IPCC’s hypothesis of dangerous, human-caused global warming has been repeatedly tested and failed. In contrast, the proper null hypothesis that the global climatic changes that we observe today are natural in origin has yet to be disproven. The only argument that remains to the IPCC—and it is solely a theoretical argument, not evidence of any kind—is that their unvalidated computer models project that carbon-dioxide-driven dangerous warming will occur in the future: just you wait and see! It is therefore to these models that we now turn.

Virtual reality. The general circulation computer climate models (GCMs) used by the IPCC are deterministic, which is to say that they specify the climate system from the first principles of physics. For many parts of the climate system, such as the behaviour of turbulent fluids or the processes that occur within clouds, our incomplete knowledge of the physics requires the extensive use of parameterisation (that is, “educated guesses”) in the models, especially for the many climate processes that occur at a scale below the 100 to 200 square kilometre size of the typical modelling grid.

Not surprisingly, therefore, the GCMs used by the IPCC have not been able to make successful climate predictions, nor to match the observed pattern of global temperature change over the late twentieth century. Regarding the first point, none of the models was able to forecast the path of the global average temperature statistic as it elapsed between 1990 and 2006. Regarding the second, GCMs persistently predict that greenhouse warming trends should increase with altitude, especially in the tropics, with most warming at around ten kilometres altitude; in contrast, actual observations show the opposite, with either flat or decreasing warming trends with increasing height in the troposphere.

The modellers themselves acknowledge that they are unable to predict future climate, preferring the term “projection” (which the IPCC, in turn, uses as the basis for modelled socio-economic “scenarios”) to describe the output of their experiments. Individual models differ widely in their output under an imposed regime of doubled carbon dioxide. In 2001, the IPCC cited a range of 1.8 to 5.6 degrees warming by 2100 for the model outputs they favoured, but this range can be varied further to include even negative outputs (that is, cooling) by adjustment of some of the model parameters. Indeed, the selected GCM outputs that the IPCC places before us are but a handful of visions of future climate from amongst the literally billions of alternative future worlds that could be simulated using the self-same models.

The confidence that can be placed on GCM climate projections is indicated by the disclaimers that the CSIRO always includes in its climate consultancy reports. For example:

“This report relates to climate change scenarios based on computer modelling. Models involve simplifications of the real processes that are not fully understood. Accordingly, no responsibility will be accepted by CSIRO … for the accuracy of forecasts or predictions inferred from this report or for any person’s interpretations, deductions, conclusions or actions in reliance on this report.”

It is clear from all of this that climate GCMs do not produce predictive outputs that are suitable for direct application in policy making; it is therefore inappropriate to use IPCC model projections for planning, or even precautionary, purposes, as if they were real forecasts of future climate. Notwithstanding, it remains the case, amazingly, that the IPCC’s claims of a dangerous human influence on climate now rest almost solely on their unrealistic, unvalidated GCM climate projections. Which makes it intriguing that during recent planning for the next (fifth) IPCC assessment report, due in 2015, senior UK Hadley Centre scientist Martin Parry is reported in a recent Nature article as saying: “The case for climate change, from a scientific point of view, has been made. We’re persuaded of the need for action. So the question is what action, and when.” Well, the IPCC may be so persuaded, but what about the rest of us?