WE must stop calling them “climate sceptics” and start calling them “climate nutters”.

I was thinking this while listening to the Great Barrier Reef Marine Park Authority’s Dr Roger Beedon – a real scientist – address a public meeting in Port Douglas this week on coral bleaching.

Like a good scientist, he was presenting the evidence. This is the worst coral-bleaching event in the reef’s history. Before the late 1990s coral bleaching was a non-event. Bleaching cannot be dismissed as something usual that occurs in cycles. Bleaching on this scale is utterly abnormal.

This January to March saw the highest sea temperatures on record in far north Australia.

Dr Beedon has no doubt the bleaching was caused by climate change in turn caused by increased greenhouse gases in the atmosphere put there by humans.

Bleaching occurs when the zooxanthellae (tiny algae) which symbiotically live inside the coral polyps are expelled by the coral when water temperatures rise. The coral can recover if the water temperature falls before other algae cover the coral and kill it.

But if temperatures normal in February continue into April (because of global warming) the chances of recovery fall.

Dr Beedon says that addressing climate change is the most important step to prevent bleaching. But given the length of time that that will take, it makes other steps to protect the reef much more significant – especially protecting it from unnecessary nutrient and silt run-off.

The science is telling us that extra carbon dioxide in the atmosphere is heating the ocean and air and this will result in the death of the Great Barrier Reef.

Scepticism about climate change was legitimate some time ago when the science was just coming in, in the same way that it was legitimate for people in the 15th century to be sceptical about whether the earth is round and goes around the sun, or it was legitimate in the middle of 19 th century to be sceptical about evolution, or in the early 20th century to be sceptical about smoking causing cancer.

But after a while so much evidence and science comes in that reasonable people accept these things as the most plausible explanations. To do otherwise is no longer sceptism but stubborn denial of the scientific method upon which so much of human prosperity depends – being a nutter not a sceptic.

The nutter will grab at any scrap of contrary explanation or evidence and exaggerate it, ignoring the great body of evidence the other way.

With scientific hypotheses like evolution and climate change eventually enough evidence comes to support it and the onus of proof reverses. It becomes incumbent on the deniers to provide another better full explanation.

Dr Beedon mentioned the importance of the Paris agreement. Given the stakes, Australia should be leading the way on reducing emissions, not lagging.

We should not listen to nutters any more, but get on with the task at hand.