1. Proxy Measures of Past Climates
Current Weather
Significance of Climate Proxies
Role of Proxies in Reconstructing Past Climate
Ice Cores
For Next Class: Read rest of Chapter 10

3. Reconstructing Past Climates: Why and How?
Climate reconstruction
Improves our understanding of environmental response to climate variability and climate change
Provides perspective on current climate
Requires identification of a link between quantitative climate
forcing and
environmental response
© AMS

4. What kinds of climate proxies can be used to estimate surface temperatures (last 2000+ years)?

5. What kinds of climate proxies can be used to estimate surface temperatures (last 2000+ years)?
Tree rings
Corals
Ocean and lake sediments (varves)
Cave deposits (speleothems)
Ice cores
Pollen deposits
Packrat middens
Glaciers
Documentary evidence (historical records, paintings, etc.)

6. Climate Proxies
Which of the climate proxies excites you the most? Why?
© AMS

7. Deciphering Past Climates
Figure 10.1

8. Ocean Sediment Cores
Figure 10.4

9. Ice Cores
Figure 10.5
Figure 10.6

10. Ice Core Videos

11. Annual accumulation preserved on Osjollo Anante Icecap, Peru

12. Quelccaya Icecap (5,670 m)
One of the most important archives in the tropics for
the reconstruction of past climates from ice cores.

13. Oxygen Isotope Analysis
Figure 10.2

14. Earth’s Long-Term Climate History
Figure 10.7

15. Earth’s Long-Term Climate History
Figure 10.8

16. Methods for Short-Term Climate Reconstruction
Short term means the order of hundreds or thousands of years.
Radiocarbon dating and the analysis of
Tree rings
Speleothems
Coral reefs

17. 14Carbon Half-Life and Tree Rings
Figure 10.9
Figure 10.10

18. Speleothems
Figure 10.11

19. Corals
Figure 10.12

20. Earth’s Short-Term Climate History: 20,000 Years of Greenland Temperatures
Figure 10.13

21. Mechanisms of Natural Climate Fluctuation
Solar variability
Earth’s orbital cycles
Continental position and topography
Atmospheric gases and aerosols