The Paleocene-Eocene Thermal Maximum
In Our Time
BBC
4.6 • 9.9K Ratings
🗓️ 16 March 2017
⏱️ 50 minutes
🧾️ Download transcript
Summary
Melvyn Bragg and guests discuss the high temperatures that marked the end of the Paleocene and start of the Eocene periods, about 50m years ago. Over c1000 years, global temperatures rose more than 5 C on average and stayed that way for c100,000 years more, with the surface of seas in the Arctic being as warm as those in the subtropics. There were widespread extinctions, changes in ocean currents, and there was much less oxygen in the sea depths. The rise has been attributed to an increase of carbon dioxide and methane in the atmosphere, though it is not yet known conclusively what the source of those gases was. One theory is that a rise in carbon dioxide, perhaps from volcanoes, warmed up the globe enough for warm water to reach the bottom of the oceans and so release methane from frozen crystals in the sea bed. The higher the temperature rose and the longer the water was warm, the more methane was released. Scientists have been studying a range of sources from this long period, from ice samples to fossils, to try to understand more about possible causes.
With
Dame Jane Francis Professor of Palaeoclimatology at the British Antarctic Survey
Mark Maslin Professor of Palaeoclimatology at University College London
And
Tracy Aze Lecturer in Marine Micropaleontology at the University of Leeds
Producer: Simon Tillotson.
Transcript
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| 0:00.0 | This is the BBC. |
| 0:02.0 | Thanks for downloading this episode of In Our Time. |
| 0:05.0 | There's a reading list to go with it on our website. |
| 0:07.0 | And you can get news about our programs if you follow us on Twitter at BBC In Our Time. |
| 0:12.0 | I hope you enjoyed the programs. |
| 0:14.0 | Hello, about 50 million years ago, the Earth's climate changed faster than at any time in our geological record, |
| 0:20.0 | reaching temperatures much higher than they are today. |
| 0:23.0 | Bad event is known as the Paleocene Eocene Thermal Maximum. |
| 0:27.0 | And with the result, it's thought, a vast volume of carbon dioxide being released into the atmosphere over a few hundred years, |
| 0:34.0 | along with methane, another greenhouse gas. |
| 0:36.0 | The Arctic and Antarctic became subtropical with crocodiles, where there's no ice. |
| 0:41.0 | Some life forms went extinct. |
| 0:43.0 | Others adjusted in the warmer acidic oceans before the Earth cooled a hundred thousand years later. |
| 0:48.0 | When we did discuss the Paleocene Eocene Thermal Maximum, |
| 0:51.0 | our Dame Jane Francis, Professor of Paleoclamatology at the British Antarctic Survey, |
| 0:57.0 | Mark Masning, Professor of Paleoclamatology at University College London, |
| 1:01.0 | and Tracy A's, the lecturer in Marine Micropaleontology at the University of Leeds. |
| 1:06.0 | Jane Francis, go and put this in context. |
| 1:08.0 | How much warmer was it then than today? |
| 1:12.0 | Well, generally through the Paleocene Eocene Geological periods, |
| 1:16.0 | we know that it was much warmer today. |
| 1:18.0 | Like you said, there were forests and the polar regions. |
... |
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