"Climate always changes. What would concern me is if climate didn't change. Then we....

"Climate always changes. What would concern me is if climate didn't change. Then we would have a climate catastrophe."

Geologist Prof. Ian Plimer: "Climates are cyclical... When we're closer to the Sun, we happen to be a bit warmer, and when we're further away, we happen to be a bit cooler... The Sun puts out variable amounts of energy... And these are the two drivers of climate: the amount of energy that's put out by the Sun, and how close we are to the Sun."

"For more than 80% of time, the planet has been warmer and wetter than now. For more than 80% of time, sea levels have been higher than now."

"We've had eight major ice ages, and each one of these ice ages started when we had more carbon dioxide in the air than now. So how could carbon dioxide drive warming?"

"So as soon as this idea of human-induced climate change appeared, we geologists thought: No, that doesn't fit in with hundreds of years of data. This sounds like a con."