The public debate over the fourth assessment report of the Intergovernmental Panel on Climate Change and what, if anything, should be done about the dire future it forecasts is extraordinary in two main respects. In one respect the public is utterly confused about the status of the IPCC forecasts; and in the second, the debate has been marked by a degree of name calling and mud slinging that puts it below the already low level of political debate in this country. And the greenhouse industry must bear much of the blame for this.
On the first point, the public at large have been confused into believing that some form of scientific consensus underpins the IPCC forecasts of major temperature increases - ranging from 1.1C to 6.4C over 100 years, with a “best guess” at about 3.4C. Consensus on this is impossible as we shall see in a moment. The general hierarchy of agreement about climate change goes something like this:
Climate Change - yes, the earth’s climate is changing. No one is arguing with that. It is always changing. Temperatures have gone up by about a degree or so, through a couple of ups and downs, since the 1860s.
Carbon dioxide increase - yes, the proportion of carbon dioxide in the atmosphere is increasing due to human activities. We have a consensus there.
Human activity is influencing climate change - there is some sort of agreement (not a consensus) on that, but certainly none on how much.
IPCC projections - no consensus, or even general agreement. The IPCC has certified its own work as being 90 per cent correct, which is nice, but there has been no external review of its work.
The nature of the work, with a lot of judgment in areas where the science is largely unknown, means that it is not possible for another group to reproduce the work. There is an honourable opposition to this method of forecasting, with the most difficult for the pro-IPCCers to ignore being: Carl Wunsch, a professor of physical oceanography at Massachusetts Institute of Technology; John Christy, Professor and Director of the Earth System Science Center, University of Alabama, Huntsville; besides a number of other eminent names.
However, these scientists have been ignored, more or less, and the debate confused to the point where the public at large believe there is a consensus on the IPCC findings.
Much more could be said on this. The ABC recently bought a program from the UK entitled the Great Global Warming Swindle which has been already attacked in the Australian media although it has yet to be shown here. (The program has been accessible through the Internet for some time.)
Further discussion on most points can be left until the program is aired, but one point it does not make is that the IPCC’s forecasting effort is unprecedented. The only comparable attempts to computer model a complex system on this scale for any length of time into the future involve the economy, but those are much simpler and are never expected to be accurate beyond about a year or so, at best.
The IPCC is, in fact, trying to predict the state of a very complex physical system a full century out when, on the panel’s own admission, scientists know nothing about most of the variables in the model (page 16 of the physical science summary of the IPCC’s fourth assessment report).
In other words, there is still considerable room for balanced scientific debate but the debate, at times, has been extraordinarily bitter, personal and involving some very dodgy debating tricks indeed.
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