1. Climate through Earth history

2. Cenozoic cooling

3. Ice Age North Polar Coverage

4. Q.: How do we know the details of temperature changes during the ice ages?

5. Oxygen isotopes and paleoclimate
As climate cools, marine carbonates record an increase in d18O.
Warming yields a decrease in d18O of marine carbonates.
JOIDES Resolution
Scientists examining core from the ocean floor.

6. It is possible to reconstruct an approximate chronology of the ice ages by measuring the oxygen isotopes in ocean sediment cores. As marine organisms perish, their skeletons are deposited on the bottom of the sea floor. The layers of deposited skeletons provide information about climate.

10. Q.: Are there any patterns in the data?

12. Spectral analysis shows these periodicities throughout record

13. Milankovitch forcing

14. Milankovitch forcing

15. Milankovitch forcing

16. High-latitude warming beginning ~19,000 BP

17. Put the insolation signal all together, compare it to the temperature data

18. Fits pretty well, but if we look at it closely, it’s not enough

19. We also see an association between CO2 and ice volume from marine sediments

20. And an association between Antarctic temperature and CO2

21. Temperature rises precede CO2 rises

22. The biological pump removes carbon from the atmosphere

24. Q. : Was the biological pump stronger during the cold periods
Q.: Was the biological pump stronger during the cold periods? How would we know?

25. During glacial times, if there were more photosynthesis, then there would be a greater difference between surface water and deep water d13C values

26. These data suggest a stronger carbon pump during times when CO2 was low

27. This relationship continues back as far as 1 Ma BP