1. MET 112 Global Climate Change – Lecture 11 Observations of Recent Climate Change Dr. Craig Clements San Jose State University Outline  How do we observe?  Recent trends in temperature  Recent trends in GHGs

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4. What does to observe mean?  Measurements –Of what?  Who compiles these measurements for governments and society?  IPCC: Intergovernmental Panel on Climate Change www.ipcc.ch Where do our observations come from? - to watch and record.

5. Temperature stations

6. Change in surface temperature in 20 th century

7. Bubbles Trapped in ice core Petit, Jean-Robert, et al (1999). “Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”. Nature 399: 429-436.

8. Ice Core layers GISP2 ice core (Greenland Summit)GISP2ice core Archived at the National Ice Core Laboratory in CO. from 1837-1838 meters in which annual layers are clearly visible. The appearance of layers results from differences in the size of snow crystals deposited in winter versus summerwintersummer Counting such layers has been used (in combination with other techniques) to reliably determine the age of the ice. This ice was formed ~16250 years ago during the final stages of the last ice age and approximately 38 years are represented here.ice age

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11. Ice Cores

12. Coring Earth’s ice sheets

13. Coring mountain glaciers

14. Ice core record

15. Ice core CO 2 record

16. Retreat of mountain glaciers: ‘visual inspection’ Boulder Glacier, Mt. Baker, Washington

17. Retreat of mountain glaciers

18. Melting of Greenland Icesheet

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20. Global rise in sea level last 20,000 years

21. Global rise in sea level in the 20 th century

22. Shorter winters in Alaska

24. Latest global temperatures