1. MET 112 Global Climate Change – Lecture 10 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

2. 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.

3. Temperature stations

4. Change in surface temperature in 20 th century

5. 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.

6. 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

7. Ice Cores

8. Coring Earth’s ice sheets

9. Coring mountain glaciers

10. Ice core record

11. Ice core CO 2 record

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

13. Retreat of mountain glaciers

14. Melting of Greenland Icesheet

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

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

17. Shorter winters in Alaska

19. Latest global temperatures

20. Current CO 2 : ~383 ppm

21. What Changed Around 1800?  Industrial Revolution –Increased burning of fossil fuels  Also, extensive changes in land use began –the clearing and removal of forests

23. Burning of Fossil Fuels  Fossil Fuels: Fuels obtained from the earth are part of the buried organic carbon “reservoir” –Examples: Coal, petroleum products, natural gas  The burning of fossil fuels is essentially –A large acceleration of the oxidation of buried organic carbon

24. Land-Use Changes  Deforestation: –The intentional clearing of forests for farmland and habitation  This process is essentially an acceleration of one part of the short-term carbon cycle: –the decay of dead vegetation  Also causes change in surface albedo (generally cooling)

27. Greenhouse Gases  Carbon Dioxide  Methane  Nitrous Oxide  CFCs (Chlorofluorocarbons)  Others

28. Methane

29. Anthropogenic Methane Sources  Leakage from natural gas pipelines and coal mines  Emissions from cattle  Emissions from rice paddies

30. Nitrous Oxide N 2 O

31. Anthropogenic Sources of Nitrous Oxide  Agriculture  Bacteria in Soils  Nitrogen fertilizers

32. CFCs (Chlorofluorocarbons) CFC-11 CFC-12

33. Sources of CFCs  Leakage from old air conditioners and refrigerators  Production of CFCs was banned in 1987 because of stratospheric ozone destruction –CFC concentrations appear to now be decreasing –There are no natural sources of CFCs

34. Latest global temperatures

35. The Land and Oceans have both warmed

36. Precipitation patterns have changed