Geologist and author Ian Plimer was the special guest on Paul Murray Live on Tuesday, in to talk about hydrogen as a potential energy source to replace coal with fill-in host Corey Bernardi. Plimer prefaced his remarks dampening enthusiasm for hydrogen by reminding viewers that the premise of our needing alternative energy was based on the falsity of the underlying assumption that carbon dioxide was driving global warming — the old battle cry of the warmists. 

But, he said, it has never been shown that it is so — sending regular panellist Nicholas Reece into a fit of derisory laughter.