Nick Minchin

Let's work to make green energy a realistic, affordable alternative, instead of stupidly trying to make conventional energy so incredibly expensive that we'll stop using it ... Nick Minchin. Photo: David Mariuz

When the film producer Simon Nasht approached me about taking part in a documentary on climate change for ABC TV, I was just a little sceptical.

While I trusted Simon, this was the ABC, not renowned for its balance on this subject. And he wanted to pit me, a grey-haired, late-50s conservative male, against an attractive, articulate, 20-something female. Was it a set-up?

Simon was persuasive, and since I was about to leave Parliament, I figured I had nothing to lose. Importantly, it might be an opportunity for opinions not normally aired on the ABC to get a run.

So began an odyssey involving 10 cities in 21 days with four film crew - to Perth, Heron Island, the Flinders Ranges, the whole time with a camera recording my every action and utterance. I look back on the experience with affection, and I congratulate the production team on the finished product, and the ABC for broadcasting it.

Anna Rose - whom I like and respect - deserves commendation for being part of it despite the pressure she was clearly under not to give a platform to dangerous and evil sceptics like me and those I took Anna to meet.

And of course Anna was a worthy opponent, and it was never going to be easy to change her mind. She has a strong conviction that mankind's use of fossil fuels will cause dangerous global warming, and brings great passion and eloquence to her advocacy.

I'm sure that I did not change her mind, but I hope she saw that not all sceptics are mad, bad and dangerous; that there remains a lively scientific debate about the drivers of climate change, and that scaremongering about global warming is backfiring on the warmists.

Professor Michael Ashley, in yesterday's Herald, expressed the usual denunciation of sceptics like me: the experts are on the global warming side; I am a cynical former politician who doesn't understand ''the science''; they have found ''the truth'' about climate - debate over.

Oddly, what he doesn't argue is exactly the science - and that is because reality has got in the way of the theory. Indeed, the absence of warming since 1998 - despite rising CO2 levels and contrary to Intergovernmental Panel on Climate Change predictions - shakes the foundations of the alarmists' cause, as the Green icon James Lovelock, father of the Gaia theory, recognised this week.

It is the arrogance of the Professor Ashleys of the world that has turned public opinion against his ilk, and prompted Lovelock to say recently that ''the great climate centres around the world are more than well aware how weak their science is''.

Anna and those of her persuasion need to recognise that public concern about global warming peaked in 2007 and has been in decline ever since, partly because the credibility of alarmists has sunk. Despite the hype of the Al Gores and Tim Flannerys, the drought has ended, our cities aren't being submerged, we still have polar bears and neither polar ice cap is disappearing.

Perhaps the most useful appointment I arranged for the documentary was with Bjorn Lomborg, the head of the Copenhagen Consensus Centre. Lomborg, unlike me, thinks human emissions of CO2 are causing global warming, but like me he thinks carbon taxes and emissions trading schemes are a stupid, costly and ineffective way of dealing with the issue. Lomborg advocates significant global investment in green energy research and development in order to make green energy so cheap everyone will want it.

Now that I can support. If there is to be any common ground between sceptics and warmists, this surely must be it. Let's work to make green energy a realistic, affordable alternative, instead of stupidly trying to make conventional energy so incredibly expensive that we'll stop using it.

One other significant appointment I sought - the footage of which lies on the cutting room floor - was with Professor Jasper Kirkby in Geneva. Kirkby is leading a team at the world-famous CERN research facility investigating the relationship between solar activity, cosmic rays and cloud formation, and the consequences for our climate. This is fascinating work which amply demonstrates how much we don't yet know about what drives our climate - and that to claim ''the science is settled'' is simply a lie. I felt that if any of the visits I proposed had shaken Anna in her convictions, this was it.

Conversely, neither Anna, nor those whom Anna took me to meet, could convince me that human emissions of CO2 are driving dangerous global warming.

What I have learnt about science recently is that it is dynamic, that there are always unknowns and that there is in particular much that we don't know about the Earth's climate.

May the debate continue.

Nick Minchin is a former Liberal senator.