Professor Ian Plimer

There are other records you can get from tree rings, from ice cores.

And they tell us a different story.

A geological record tells an even more exciting story.

So for ice cores, the original ice cores that were drilled used volcanic eruptions and dated the ash and the acid in those cores.

Then you could work out the rate of ice deposition.

And then with that, as snow falls and is compressed into ice, it traps little bits of air and you can extract that air and measure the amount of carbon dioxide in it.

You can also, from chemical fingerprints in the ice, you can work out at what temperature it formed.

So then you get a correlation between carbon dioxide and temperature and time.

And that showed a perfect relationship.

You could see these Milankovitch cycles, you could see the three cycles, and you could see that carbon dioxide followed exactly the temperature.

But with more detailed sampling, a totally different story came out.

And the story was that you will get a period of natural warming

And some 600 to 1600 years later, you get an increase in carbon dioxide.

Now, we've known that from chemistry for 200 years.

You know, if you want to sit down with a carbonated drink like a champagne or a beer or a soft drink, commit a sin.

Don't drink it.

Just watch it.

And as it warms up, it keeps bubbling out carbon dioxide.

That's what happens to the oceans.

So you warm the atmosphere, and later the oceans will release carbon dioxide.