The Australian government is planning to introduce an emission’s trading scheme, also described as a carbon pollution reduction scheme, on the basis that that carbon dioxide from the burning of fossil fuels is contributing to dangerous global warming.
Many people assume that such a drastic action is premised on good evidence establishing a proven causal link between anthropogenic carbon dioxide and global warming.
For example, when establishing causality between an environmental pollutant and an effect on an animal species, scientists would be expect to establish not only a correlation between the presence of the pollutant and an effect (for example an illness in the population), but be also able to demonstrate a dose-response relationship and describe a credible toxicological basis for the proposed mechanism linking the proposed cause and effect.
Interestingly while anthropogenic carbon dioxide is now considered to be one of the worst pollutants,
there does not appear to be a body of work establishing the basic criteria for a claimed causal relationship between the purported pollutant, anthropogenic carbon dioxide, and the claimed effect, global warming; atleast not outside of the United Nations Intergovernmental Panel on Climate Change reports. In particular there does not appear to be a body of work published in reputable scientific journals.
Furthermore, much of the science underpinning the need for a proposed carbon pollution reduction scheme in Australia appears to be based on the claim of a scientific consensus and the observation that there have been increasing levels of atmospheric carbon dioxide over the last 150 years and over this period temperatures have also been generally increasing.
I posted a note on my blog and John Quiggin’s blog on Sunday evening suggesting this deficiency and requesting “research results that have been published in reputable scientific journals that: 1. examine the causal link between anthropogenic carbon dioxide and warming, and 2. quantify the extent of the warming from anthropogenic carbon dioxide.”
Several papers were suggested to me, I believe in good faith, as fulfilling this criteria including a paper entitled ‘Causes of Climate Change Over the Past 1,000 Years’ by Thomas Crowley (14 July 2000, Vol 289, Science).
I was disappointed with the paper when I read it this afternoon. The paper essentially compares output from a reconstruction of past climate with output from an energy balance climate model. In other words, the paper looks at the fit between output from two models. So the paper is about correlation not causation.
But most disappointing, the reconstruction of past climate in the Crowley paper is based on the work of Michael Mann and colleagues which has been the source of much controversy and many believe completely discredited by a report from a team of statisticians led by Edward Wegman, chair of the National Academy of Sciences’ (NAS) Committee on Applied and Theoretical Statistics, assembled at the request of U.S. Rep. Joe Barton and U.S. Rep. Ed Whitfield .
Indeed what has become known as the hockey stick controversy is illustrative of the nature of climate science in what Aynsley Kellow, Professor and Head, School of Government, University of Tasmania, has described as post-normal science with an extensive reliance upon models and the potential for significant manipulation of their source data.