Beware of doomsday forecasts

Many people are thrilled by a good, action-packed disaster movie complete with erupting volcanoes, tidal waves, floods, pestilence and of course, a war. 

Recently the NSW Premier, Bob Carr, released a report by CSIRO titled Climate Change in New South Wales that alerted us to the potential for all of this - well I am actually extrapolating and exaggerating. The report did mention the potential for more frequent droughts, heat-waves, high waves, rainstorms and extreme winds. 

It was all about the future based on “scenario modelling”. They could have “scenario modelled” a war and volcano into the consultancy if they had wanted.

But after all, the work was to be done by CSIRO and they presumably wanted it to at least have the guise of science. I wouldn’t increase my insurance premiums just yet, though.

Scenario modelling is not about forecasting but rather exploring different possibilities. The CSIRO climate change modelling is based on the work of the Intergovernmental Panel on Climate Change (IPCC) and this organisation makes the point that “in climate research and modelling we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that long-term predictions of future climate states is not possible.”

Given the nature of the “computer games” that the researchers are playing with or working on, it is really inappropriate for Mr Carr to use terms such as “NSW can expect” and “it will mean” and “most likely” in explaining the relevance of the report’s findings.

While the report is big on what might happen, there are only three small paragraphs about “observed climate variability in NSW”. This includes reference to an increase in hot days (35C or more) of 0.10 days per year and an increase in hot nights (20C or more) of 0.26 nights per year since 1950. I must admit I was expecting the measured statistics to show a bit more change than this.

The current political situation, particularly the focus on doomsday scenarios, seems somewhat reminiscent of the situation in the 60s and 70s when the Club of Rome was announcing the imminent exhaustion of our non-renewable resources and Professor Paul Ehrlich of Stanford University wrote, “The battle to feed all of humanity is over. In the 1970s the world will undergo famines - hundreds of millions of people are going to starve to death”.

Professor Ehrlich also predicted that life expectancy in the United States would drop to 42 years as a consequence of the use of pesticides.

Of course life expectancy has continued to increase and we didn’t all starve to death. Technological innovation, including modern high yielding agriculture, has enabled farmers to feed a world population that has doubled during the last 30 years from essentially the same area of land (about 1.5 billion hectares).

It was another Stanford professor that wrote:

Like most people (we scientists) would like to see the world a better place. To do this we need to get some broad based support, to capture the public’s imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified dramatic statements, and make little mention of any doubts we might have. This “double ethical bind” we find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest.

I reckon it would be a lot simpler if the scientists mostly stuck to hypothesis testing based on observation, experimentation and tested theory, and left the doomsday scenario modelling (including climate change modelling) to Hollywood and the film directors.