Yesterday was Commonwealth Day. The theme was the environment, but some of the diplomats and politicians celebrating at Parliament House Sydney did not realise they were about to be shaken out of their complacency on climate change.

Like most politicians, economists, lawyers, readers of Crikey and me, the knowledge of the audience about global warming was probably pretty limited.

They weren’t challenged when Governor Professor Marie Bashir, after reviewing the massed flag bearers and being piped in, read the carefully considered message on the environment from The Queen. (Her Majesty’s personal message, not her ministers.) It was the keynote speaker who was to shake them — Professor Ian Plimer, who lives and breathes the subject.

In a witty and provocative speech, without notes, he reminded the audience that consensus and belief are alien to science. He challenged the current orthodoxy about global warming and climate change mantra because he says it’s based on a fundamental error.

This is the belief that humans live on a non-dynamic planet. Change he says is perfectly normal and is driven by a large number of natural forces. It can be slow or very fast. By using the past as the key to the present, we are facing the next inevitable glaciations.

Yet the current climate, economic, political and social models are about assessing the impact of a very slight warming. They don’t, he says, assess the bigger problem and higher risk of yet another ice age.

Yet geology, archaeology and history show that during such glaciation, famine, war, depopulation and extinction are the norm. Just as he is the foe of creationism, he believes the current orthodoxy on the cause global warming is fraudulent.

To some of the diplomats and politicians this must have been an unwelcome heresy. If Plimer were ever pressured to abjure, as some say university climate dissenters should be, I can just imagine him muttering “E pur si muove.”