In computer models we trust!
The coming Senate vote on the badly misnamed Carbon Pollution Reduction Scheme (CPRS) is the culmination of intense propaganda spanning more than three decades. The Senate Bill aims at restricting emissions of carbon dioxide, a colourless, odourless gas essential to life, and has nought to do with smokestack carbon particles and other pollutants that have been regulated since the 1950s. The basis of the Bill is an unsustainable hypothesis that dangerous global warming will be an outcome of continued burning of fossil fuels and the rising concentrations of carbon dioxide in the atmosphere.
It is nearly 20 years since the UN’s Intergovernmental Panel on Climate Change (the IPCC) in 1990 gave its first assessment of the likelihood and potential magnitude of human-caused global warming. In their first report in 1990 they confirmed that humans would have an impact on global temperatures as carbon dioxide levels increased. Importantly, the magnitudes of impacts were considered conjectural and subject to large uncertainty, because computer models of the time were rudimentary in their ability to represent the complex processes in the climate system.
The IPCC’s second report in 1995 was more confident, saying that the balance of evidence suggested a discernible human influence on global climate. By the time of the 2001 third report the IPCC was concluding that the ability of computer models to project future climate had increased and ‘the warming over the past 100 years is very unlikely to be due to internal variability alone, as estimated by current [computer] models’.
In its most recent 2007 report the IPCC has gone so far as to claim that most of the warming of the last half century was very likely due to human activities, especially the emissions of carbon dioxide. Moreover it was claimed that unconstrained emissions of carbon dioxide would lead to a dangerous global temperature rise of between 2oC and 6oC by the end of the century.
Unfortunately the more recent pattern of global temperature does not fit the IPCC scenario. Carbon dioxide levels have continued to rise but global temperatures have flat-lined since 1997.
In light of the recent global temperature record it is appropriate to ask the government – as indeed, Senator Fielding has - why 1998 remains the warmest year in the record and why global average temperatures have persisted at about the same value (0.4oC above the 1961-1990 average) since 1997. After all, given the carbon dioxide emissions that have occurred, even the most conservative IPCC predictions are that the temperature should have risen by at least 0.2oC over the decade, and up to 0.6oC rise could have been expected.
The recent temperature record exposes the logical inconsistency within the IPCC argument for ‘dangerous’ human-caused global warming.
If there is only limited internal variability in the climate system, as IPCC claimed in its 2001 assessment, then global temperature should respond to the increasing levels of carbon dioxide according to the computer model predictions. As the global temperature is not following the trend of increasing carbon dioxide levels, then we must conclude that IPCC and its computer models have got it wrong. Carbon dioxide is clearly not the climate bogey that it has been made out to be.
Those who have an understanding of the climate system recognise the reality of the last decade. Internal variability of the climate system gives rise to important fluctuations, such as the El Niño Southern Oscillation. Subtle changes in the surface layer circulation of the equatorial Pacific Ocean have global impact on climate, including Australian rainfall.
There are other well-known multi-decadal variations in the ocean circulation that also impact on the global climate. These include the Pacific Decadal Oscillation (PDO) and the North Atlantic Oscillation (NAO).
The Rudd government plans to implement its Carbon Pollution Reduction Scheme (CPRS) on the basis that reducing carbon dioxide emissions to the atmosphere will avert dangerous climate change. Legislation giving effect to cap and trade permits is awaiting consideration by the Senate. Implementation of the scheme will impact on every Australian; the greater the government commitment to reduce carbon dioxide emissions, so the greater that impact will be.
It is clear that complex computer modelling of the climate and economic systems, both based on questionable assumptions, are respectively the reason and the justification for the cap and trade legislation. For most of us, computer models are synonymous with the magician’s smoke and mirrors; in the experts we trust. Until recently there was no simple benchmark against which to assess the veracity of either the climate or economic computer projections.
However, we now have a decade of independent climate data and the ‘dangerous’ global warming predictions of the IPCC have proved to be a chimera, as global temperatures have not risen.
There is a serious risk that we will end end up with the worst outcomes possible because of the frailties of computer modelling: carbon dioxide will prove to have little impact on climate but implementation of the Rudd government’s cap and trade legislation will seriously raise energy costs and expand unemployment. Additionally, serious power outages have recently been foreshadowed because the cap and trade penalties discourage necessary investment and maintenance for conventional power generation infrastructure.
It is time to make a fundamental re-assessment of our knowledge of climate, especially giving emphasis to past change as a guide to the future. Rather than attempting to control climate through regulating carbon dioxide, the Rudd government would do better to invest in adaptation measures that improve community resilience to known climate hazards, both natural and potentially of human causation.
William Kininmonth is a meteorologist and former head of Australia’s National Climate Centre. He was Australian delegate to the World Meteorological Organization’s Commission for Climatology (1982-98), including two terms on its management board and is the author of Climate Change: A Natural Hazard (2004, Multi-science Publishing Co, UK).