It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. Sherlock Holmes (aka Arthur Conan Doyle)
In 1853-54 there was a serious outbreak of cholera in London’s Soho district. The prevailing view of scientists at the time was that cholera - like climate change now - was caused by an invisible miasma in the air, and the Ross Garnauts of that time all deferred to various Royal Societies (e.g. the Royal College of Physicians) as the definitive authorities. John Snow, a doctor who had pioneered the use of chloroform, in 1849 published at his own expense the first book to challenge the conventional wisdom of the authorities of the day, and was duly put down by them. However Snow persevered, and showed how the incidence of cholera in the 1854 outbreak was closely correlated with the nature of the drinking water supplied by the Southwark and Vauxhall water company on the one hand, and the Lambeth company on the other. He eventually won acceptance for his contention that cholera is a water-borne disease, having shown statistically how most cholera deaths occurred in premises taking their water from the first company, which had its water intakes adjacent to sewerage outlets to the Thames, while very few deaths occurred in premises whose water was supplied by the Lambeth company, which in 1849 had moved its intakes up-river from the sewerage outlets.
Snow’s pioneering counterfactual analysis has recently been cited in two econometrics textbooks (Angrist and Pischke 2009, Freedman 2010) that explain how multi-variate regression analysis can be used to evaluate competing theories of causation. The full version of this paper (available at www.lavoisier.com.au) shows how such analysis reveals that changes in atmospheric water vapour are a much more powerful explanation of climate change than changes in carbon dioxide levels, because like Snow it uses counterfactuals to show that although the atmospheric concentration of carbon dioxide is ubiquitous (the same everywhere), temperature changes are not, and that in most places changes in atmospheric water vapour have a very much larger – and much more statistically significant – association with changes in temperature . Were he alive now it seem more than likely John Snow would have been as sceptical of airborne carbon dioxide being the cause of changing climate everywhere as he was of miasmic air being guilty of spreading cholera.
Ross Garnaut’s Update 5 The Science of Climate Change is notable for its avoidance of econometrics and counterfactuals, and concludes (in its section 4.2.2) by invoking the authority of the Royal Society, the National Academies of Sciences (USA), and the Australian Academy of Science with their support for the findings of the International Panel on Climate Change that global warming is caused by airborne carbon dioxide. In an uncanny repeat of the views of the peak authorities in 1850, the IPCC’s Climate Change 2007.The Physical Science Basis goes out of its way (Solomon et al. 2007:28) to dismiss any role in climate change for the emissions of water vapour that are simultaneous with emissions of carbon dioxide whenever there is combustion of hydrocarbon fuels. Yet basic chemistry and physics show that while water vapour emissions are only in the range of 30-50 per cent of CO2 emissions by weight, in addition to any moisture content of the fuel, their effect on surface temperature is much larger. A typical formula for combustion of hydrocarbon fuels is:
C3H8 + 5O2 + 18.8N2 → Energy + 3CO2 + 4H2O +18.8N2
To the best of my knowledge this formula does not appear in any of the IPCC sources relied on by Garnaut, no doubt because it would be very inconvenient to mention that CO2 “pollution” includes rainfall generated by the atmospheric water vapour resulting from the H2O term, which amounted in 2008-2009 to 17.5 GtH2O compared with 31.4 GtCO2 (for sources see full paper). If the CO2 is a bad, does that extend to H2O as well?
It follows that the tax on carbon to be proposed by Garnaut’s Update No. 6 (17th March 2011) will also be a tax on water vapour and thereby, unavoidably, on rainfall. The political implications of that remain to be played out, but it is characteristic of all the Garnaut work on climate change that it dwells only on the supposed external costs of hydrocarbon combustion and never mentions the demonstrably larger benefits of elevated atmospheric carbon dioxide and rainfall – not to mention warmer temperatures – on the world’s primary production (see Table 1 for data).
Carbon Dioxide and World Cereals Production 1961-2007
Source: www.globalcarbonproject.org (Le Quéré et al. 2009), FAO 2009.
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