Past climates, CO₂ and warming

Professor Matthew Huber explains what polar environments were like 50 million years ago and why CO2 is the best explanation for changing climates.

Transcript

Professor Matthew Huber

We know that the high latitudes, the polar regions were ice-free. There was no glaciers, there was no snow, it did not go below freezing in the wintertime, and as far as we can tell, there were large forests going all the way up to the north coast of Greenland. There were crocodiles near the North Pole, and there’s also fossils of tortoises and a whole variety of subtropical plants. This was clearly a subtropical swamp environment during the warmest periods in the Eocene – more like the coast of Florida than the North Pole is today.

We are also quite sure that, in the mid latitudes – so between 30° of latitude and 60° of latitude – that the planet was much warmer than it is today, easily 10° warmer, perhaps more than that warmer, and we also think that it was significantly wetter, a lot more rain and perhaps less evaporation.

Our best explanation of much of that climate change is carbon dioxide. If you take that out of the mix, then you’re left with magical factor x – this unexplained thing that has changed climate through time and CO2 hasn’t, because you have to believe simultaneously that both of those are true – CO2 hasn’t done it and some other mythical factor has.

Acknowledgements

This video is an extract from Thin Ice – The Inside Story of Climate Science, a David Sington/Simon Lamb film.

The full documentary film is available by emailing thiniceclimate@vuw.ac.nz. The link for streaming is available free of charge. The DVD is also available to New Zealand schools for $20 to cover costs.