Scientific certainty in an uncertain world

This approach has been resoundingly endorsed by such outstanding legal scholars as Mr Justice Glass in the New South Wales Court of Appeal, and our current Chief Justice, Justice Spigelman. The law also requires that expert opinion must truly be expert, it must be non-partisan and it must expose its reasoning processes to popular scrutiny.

If a Court were to determine a case about human induced climate change on these principles it would examine, first, whether or not the scientific evidence allowed for the possibility of human activity contributing to overall levels of greenhouse gas. That having been established then the court would determine whether or not there is a probable connection - more likely than not - by looking at the scientific evidence in conjunction with other relevant facts bearing on the issue, like what’s actually happening.

Many, if not most, reputable scientists actually engage in similar processes although they tend to apply a more rigorous approach in the sense of applying tenets of scientific, mathematical and statistical processes to determining "facts". They still draw inferences, but like judges they can't rely on conjectures or guesses.

An excellent example of this approach by scientists is an article published in Nature in 2001. The authors analysed changes in the spectra of longwave radiation as measured by orbiting spacecraft and concluded that their analysis provided "direct experimental evidence for a significant increase in the earth's greenhouse effect that is consistent with concerns over radiating forcing of climate". The paper makes compelling reading, and I'm not aware of the author's approach having been demonstrated to be unsound or unscientific.

In the climate change “debate”, however, the argument tends to be aimed at specific end events and not at the more important basic premises. For example, it’s probably impossible to say with certainty that events like the Black Saturday bushfires or Hurricane Katrina were directly “caused” by greenhouse gas emissions, but it is a scientific certainty that rising greenhouse gas emissions are changing and will change our climate.

But to a large extent these comments are by the by because we are dealing with a manufactured controversy and there is no real "debate". It is simply no longer acceptable for a small number of climate change struthonians to be given undue airtime to prolong their filibuster. Nor should they get away with their scientifically dishonest attempts to refute climate change science by engaging in tactics like deliberately commencing data from an el Niño year like 1998 to skew results. Or putting forward data which examines trends over only a cherry-picked short period rather than scientifically significant periods like 20 years or more. Or the much-repeated gaffe of asserting that in the past Earth experienced much higher air temperatures and much higher CO2 than we have today, without also pointing out that those times include the Eocene 40 million years ago, when humans didn’t exist and sea levels were 50 metres higher than today.

It's about time we saw reputable scientists and scientific bodies coming out - as we have in recent days with the Bureau of Meteorology and CSIRO report and with Australia's Chief Scientist - to tell the general public what the evidence clearly shows.

In any case, isn't there a common sense general argument in support of action to reduce human greenhouse gas emissions? The propositions might go something along the following lines:

1. C02 is a gas that has well-measured greenhouse effects (UK physicist John Tyndall first demonstrated this in the 1850s).
2. C02 levels have risen since the industrial revolution and are now rising rapidly.
3. The existing overall concentrations of C02, even without any further increases, could have dangerous environmental consequences.
4. Human activity generates an increasing quantity of C02. We are certain of the human component of CO2 in the atmosphere from isotopic analysis. Isotopic analysis shows that human generated C02 is the major contributor to the increased greenhouse gas levels of the past few centuries.
5. Irrespective of the proportional extent of the human contribution to overall C02 levels, the only thing we can do is to act by changing what we do and how we do it to reduce our contribution to the overall C02 level.
6. Humans can reduce the level of C02 they generate by changing their behaviour and in particular by ramping up use of low-carbon technologies.
7. Therefore, we must change our behaviour and do what we can to reduce our generation of greenhouse gases.

The message for all of our politicians is clear: the people in whose interests you govern, whether you know it or not and whether you like it or not, need a stable climate to live, to work, to raise their families, to love and to grow old. Just as birds need trees and polar bears need ice. Humans aren’t unique. And whether you know it or not, our entire physical environment - our cities, our infrastructure and our patterns of land use - all were established during a very stable climate era. Did you notice that Frisch wrote about "Man in the Holocene", not beyond it!

Scientists aren’t scare-mongering when, almost unanimously in both numbers and disciplines, they describe the challenges we will face with an average global temperature rise of more than 2 degrees. The impacts become even worse at temperature increases of 3 degrees and above, a warming level we are headed for without action to reduce emissions. We citizens know it’s happening, too, which was an important part of why we booted out the Howard government in 2007.

If you choose to accept the manufactured controversy promoted by a small number of naysayers and eco-backsliders, and say that the “room for debate” justifies your inaction, you are failing in your duty to those you represent. You won’t maintain the status quo by doing nothing because the destabilisation will continue, and if you do nothing it will accelerate. If you adhere to some naïve notion that we can adapt our environment to suit us rather than we having to adapt to our environment you are demonstrating one defining characteristic that does make some humans unique: an ignorant anthropocentricity reeking of selfishness as individuals and as a species.

Fortunately most people didn’t hold that view in 2007, and they don’t hold it now. If you continue to sit on your hands, gagged by the filibustering, may you pay the appropriate price when you next face the electorate!