So my time has come to pick a paddock.

After years of racking my brain, reading all the evidence I could, listening to many people and deciding who had credibility and who did not, I have decided the world’s climate is changing and mankind has had some influence on that.

Many people have told me there is no such thing as global warming, but most can only produce a couple of scientists — usually of questionable credibility — and scraps of doubtful science to back their claims.

In making my decision I excluded the bullies from the extreme right media — who criticise “global warmists” but are choosey about who is caught in that net — and those who have a financial interest in bagging the climate change theory.

I then chose those who I believe have some credibility, such as Sunny Verghese, who appeared on Landline recently and (drawing from the official transcript of the show) warned Australian primary producers to take climate change seriously.

Mr Verghase is the head of Olam International, a company based in Singapore which has business interests in 65 countries and is the world’s biggest trader in cashews and the second biggest trader in coffee and cotton — which I reckon gives him plenty of points in the cred stakes.

He told Landline it is absolutely a reality that climate change is going to significantly impact agriculture and outlined his company’s plans to reduce its carbon dioxide footprint, saying there is no point generating half-a-billion after tax earnings but depleting $200 million of natural capital from the environment.

“Because then I’ve got to question myself, what is the point of all this overwhelming effort if at the end of the day you’ve really depleted the natural capital and left a huge bill for future generations,” he said.

He also noted the efforts of the Chinese when it comes environmental challenges.

“I don’t think there’s any other government in any other part of the world that is investing as much money now in research to solve this problem — China is at the cutting edge now,” he said.

Three former Australians of the Year — Nobel laureate Peter Doherty, epidemiologist Fiona Stanley and immunologist Sir Gustav Nossall — have signed an open letter to Prime Minister Tony Abbott, published in the Medical Journal of Australia, calling for climate change to be included on the agenda for the G20 leaders summit in Australia in November.

According to Dan Harrison in the Sydney Morning Herald of August 12 the letter, supported by a dozen health experts, says “... current climate trends, driven by global warming, threaten the basis of future economic prosperity, regional political stability and human health ...”.

Former deputy prime minister Tim Fischer is the vice-president of Global Crop Diversity Trust, based in Germany, which has seed vaults in Norway where thousands of varieties of rice, wheat and other cereal crops are stored for research.

He has been reported as saying the tough decades ahead will require many innovations to increase harvests on the same amount of land, build resilience to climate catastrophes, and reduce emissions, all at the same time.

The Liberal Party’s official policy is that: “We will take direct action to reduce carbon emissions in a practical, affordable way inside Australia, not overseas. We remain committed to a 5per cent reduction in emissions by 2020.”

If those of us in the pro-climate change camp are wrong, we will be responsible for disrupting the world economy, perhaps in a major way.

But if the anti-warmist activists are wrong they will be condemning future generations of Australians to a horrible fate.