Geologist, Professor Ian Plimer

Geologist, Professor Ian Plimer:

"[Six of the six] great ice ages started when we had more carbon dioxide in the atmosphere than now. We have 0.04% of that gas in the atmosphere... Well that means nothing to me, because the atmosphere has changed in its carbon dioxide content from over 20% to now, which is really low in geological time. If we halved it, all plant life would die, and animals would die."