Thursday, Sept 18, 2008
Dr. Iain Stewart’s new BBC2 series Earth: The Climate Wars promised to be a ‘definitive guide’ to the climate debate. Instead, this week’s episode ‘Fightback’, which focused on the sceptics was as shallow and as hollow as any old commentary. The film’s blurb on BBC iPlayer, advertises it thus:
Dr Iain Stewart investigates the counter attack that was launched by the global warming sceptics in the 1990s.
At the start of the 1990s it seemed the world was united. At the Rio Earth summit the world signed up to a programme of action to start tackling climate change. Even George Bush was there. But the consensus didn’t last.
Iain examines the scientific arguments that developed as the global warming sceptics took on the climate change consensus. The sceptics attacked almost everything that scientists held to be true. They argued that the planet wasn’t warming up, that even if it was it was nothing unusual, and certainly whatever was happening to the climate was nothing to do with human emissions of greenhouse gases.
Iain interviews some of the key global warming sceptics, and discovers how their positions have changed over time.
Before the film has started, it is clear that it lacks objectivity. Notice how the blurb casts the players of the debate as either ’scientists’ or sceptics’, as if they were mutually exclusive terms. Notice too, how it is supposed to be important that ‘positions have changed over time’, as though the counterpart argument had such integrity that it had never shifted, or responded to emerging evidence. Third, Stewart characterises the 1992 Rio summit (both in the blurb and in the film) as evidence of a consensus, which was seemingly attacked by ‘the sceptics’, when in fact, agreements and frameworks since then have failed for their non-viability, not because of any attack. And there was no such consensus in 1992. As we have pointed out before, in 1992, the ‘consensus’ was characterised very differently to today, and the UNFCCC agreements proceeded not on the basis of scientific evidence and certainty, but according to the precautionary principle.
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As the headlines of the 1995 Summary for Policymakers from WGI of the IPCC’s Second Assessment Report (a far slimmer document than today’s reams and reams of graphics and text) shows, the claims to have understood the climate were much more cautious than Stewart implies.
Our ability to quantify the human influence on global climate is currently limited because the expected signal is still emerging from the noise of natural variability, and because there are uncertainties in key factors. These include the magnitude and patterns of long term natural variability and the time evolving pattern of forcing by, and response to, changes in concentrations of greenhouse gases and aerosols, and land surface changes. Nevertheless, the balance of evidence suggests that there is a discernible human influence on global climate. […]
1. Greenhouse gas concentrations have continued to increase
2. Anthropogenic aerosols tend to produce negative radiative forcings
3. Climate has changed over the past century
4. The balance of evidence suggests a discernible human influence on global climate
5. Climate is expected to continue to change in the future
6. There are still many uncertainties
Contrary to Stewart’s claim that the world was united by scientific evidence in the early 1990s, even by 1995, there was still only the ’suggestion’, on the ‘balance of evidence’, that there had been a ‘discernible human influence on global climate’ – and that’s in the Summary for Policymakers document, which has consistently been far more alarmist than the more technical parts of the report. The First Assessment Report, which would have been the basis for the 1992 UNFCCC had concluded that ‘The unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more’, making it clear that in the early 1990s, there could have been no consensus as Stewart describes it. As the 1995 report continued:
There are still many uncertainties
Many factors currently limit our ability to project and detect future climate change. In particular, to reduce uncertainties further work is needed on the following priority topics
• Estimation of future emissions and biogeochemical cycling (including sources and sinks) of greenhouse gases, aerosols and aerosol precursors and projections of future concentrations and radiative properties.
• Representation of climate processes in models, especially feedbacks associated with clouds, oceans, sea ice and vegetation, in order to improve projections of rates and regional patterns of climate change.
• Systematic collection of longterm instrumental and proxy observations of climate system variables (e.g., solar output, atmospheric energy balance components, hydrological cycles, ocean characteristics and ecosystem changes) for the purposes of model testing, assessment of temporal and regional variability, and for detection and attribution studies.
Future unexpected, large and rapid climate system changes (as have occurred in the past) are, by their nature, difficult to predict. This implies that future climate changes may also involve “surprises”. In particular, these arise from the nonlinear nature of the climate system. When rapidly forced, nonlinear systems are especially subject to unexpected behaviour. Progress can be made by investigating nonlinear processes and subcomponents of the climatic system. Examples of such nonlinear behaviour include rapid circulation changes in the North Atlantic and feedbacks associated with terrestrial ecosystem changes.
If there were still substantial uncertainties in 1995, then the characterisation of sceptics as changing their argument is highly disingenuous. The arguments they were responding to changed. Before the film has even started, it is apparent that it has false premises.
And in case viewers are still in any doubt about which ’side’ Iain Stewart is on, the first words he speaks are ‘Global warming – the defining challenge of the 21st century’. This series is obviously intended as the antidote to the Great Global Warming Swindle. Indeed, don’t expect any complaints from the likes of the Royal Society about this one. If this is the definitive guide to anything, it is to how to dress up politics as a science documentary.
The film begins its exploration of the scientific arguments by outlining the sceptic’s objection to confidence placed in the temperature record obtained by weather stations, on the basis that they were too widely distributed to provide an accurate representation of global temperature. Stewart shows how this method had produced an upward trend throughout the 20th Century, but that it contradicted the satellite record produced after the late ’70s. Stewart asks which one is correct – the surface record, or the satellite data?
This article was posted: Thursday, September 18, 2008 at 3:47 am