1. Oxygen isotopes and climate

2. The long term average of temperature and precipitation (30 years)

3. Instruments collect data about temperature and precipitation

5. If it will impact our welfare

6. This is a proxy.

7. A proxy is a substitute. Did nature leave proxies for temperatures and precipitation from the past? YES!

8. Tree Rings Width of growth rings indicate temperature and moisture conditions.

9. Lake Varves Thickness of light layers indicate deposition due to spring melting.

10. 18 O Two types of oxygen isotopes 16 O

11. HH HH 18 O

12. shell composition: CaCO 3 O-O- HH O Ca + Foraminifera (forams) C+C+

13. 18 O/ 16 O CaCO3 The shell is analyzed to determine the 18 O/ 16 O ratio.

14. Non-glacial period H 18 O H H 16 O H H H H H H H H 18 O H H H H 16 O H (warm atmosphere) Seashells are enriched with 16 O ( 18 O/ 16 O is small)

15. Period of glaciation H 18 O H H 16 O H H H H H H H H 18 O H H H H 16 O H Seashells enriched with 18 O ( 18 O/ 16 O is larger) (cold atmosphere) glacier

16. Secrets of the Sediments Task: To analyze sediments collected off the coast of Santa Barbara to determine whether this information can be used to study historical climate change.

17. Let’s look at the results

18. Your graph should look like this today past

19. 4a. Look at the graph and describe what you see. The highest ratio of 18 O : 16 O fluctuates over time. today past

20. 4b. During what three ages or time periods can you find the highest 18 O: 16 O ratios? The highest 18 O : 16 O ratios are approximately 20,000 years ago, 65,000 years ago and 135,000 years ago. ice age today past

21. 4c. Identify and list the time periods with the lowest 18 O ratios. lowest 18 O ratios. The lowest 18 O : 16 O ratios are approximately today, 42,000 years ago and 125,000 years ago. inter-glacial today past

22. 4d. Why do you think this pattern occurred? What might have been happening geologically? What might have been happening geologically? Climatologically? Climatologically? Glaciers were melting and growing larger; the atmosphere was warming and cooling. today past

23. 4e. Predict and explain what will happen to 18 O : 16 O ratios as global warming continues. 18 O: 16 O ratios will move closer to 1 : 1 as more water melts from the ice caps and enters the oceans. today past

24. 4f. Do you think the levels of 18 O can also indicate the amount of ice found on land? Explain. Yes. If there are high 18 O: 16 O ratios, we can assume that there are larger amounts of ice on land, as the 16 O would be “locked up” in the glacial ice. today past

25. Conclusion: The 18 O/ 16 O ratio within foraminifer shells can be used to learn about past environments.

26. School of Rock Joidesresolution.org

30. Oxygen isotopes and climate NESTA workshopDeep Earth Academy activity