Today’s Topics Regarding Global Effects

1. Today’s Topics RegardingGlobal Effects Future CO2 Forcing Climate Sensitivity – Feedbacks Natural Short and Long-term Forcings Global Warming Impacts

2. Kaya Identity Model kaya identity model

3. Future Atmospheric CO2 One emission scenario Range of predictions suggest double pre-industrial by mid-century

4. Stabilization Scenarios 2100 2200 2300 2000 What our emissions can be for different constant CO2 levels. What do these tell us about future biosphere and ocean sinks?

5. Committed to Warming: Time Response

6. A Long View of Fossil Fuel Perturbation

7. Climate Sensitivity-All about Feedbacks T = F • is climate sensitivity parameter  units: K “per” W/m2  determined by feedbacks!

8. Estimates of Climate Sensitivity T change for a 4 W/m2 forcing (i.e. “double CO2”) Most probable  ~ 0.75 K/(W/m2)

9. Feedbacks “feedback loop” +/- +/- State Variable Process or coupling Initial Forcing + increases state variable - decreases state variable

10. Ice-Albedo Feedback Albedo - Example of a positive feedback More solar radiation absorbed + Temperature + Initial Forcing (e.g. GHG) Ice melts, dark soils exposed

11. Water Vapor-Temperature Feedback Water Vapor + Increased Greenhouse effect + Temperature + Initial Forcing (e.g. GHG, solar radiation) More evaporation, saturation vapor pressure increase

12. Atmosphere—Protector of the Oceans? water trap If H2O reaches top of atmosphere it is blown apart by UV radiation H atoms escape to space, never to return Probable cause for no H2O on Venus

13. IR Flux-Temperature Feedback Outgoing IR flux increases + Example of a negative feedback - Temperature + Initial Forcing (e.g. GHG)

14. Phytoplankton-DMS-Marine Cloud Feedback Charlson, Lovelock, Andreae, Warren “C.L.A.W.” Hypothesis aerosols and cloudiness + - Solar Radiation (Temperature) Biogenic Sulfur Emissions + Initial Forcing (decreased clouds) + + Photosynthesis

15. Cloud Forcings and Feedbacks Low altitude thick clouds  Stratus High altitude thin ice clouds  Cirrus

16. Aircraft emit particles (and particle precursors) which can nucleat clouds. This activity gives rise to a • Positive radiative forcing • Negative radiative forcing

17. Aviation Contrails—Positive Forcing October 2004

18. Clouds and Climate—a complex problem Cirrus: Not so reflective, but absorb and emit at cold T Low Clouds: Absorb IR but emit like warm surface. Reflective

19. Clouds and Cloud Feedbacks Albedo + - Low Clouds + + Atmosphere holds more water Increased greenhouse effect + + High Clouds + Atmosphere holds more water Uncertain! Temperature Initial Forcing (e.g. GHG, solar radiation) Temperature

20. Predicted Changes in Cloud Forcings IPCC 2007

21. Sunspots – Cyclic Changes in Solar Output

22. ~11 year Sunspot Cycle

23. Radiative Forcing by Solar Cycle

24. The solar cycle forcing has increased from -0.1 to 0.2 W/m2 since 1900. This forcing can explain ____ of 1oC increase in global Avg. T since 1900 • 60 - 70% • 40 - 50% • 20 - 30%

25. False Assertions: Sun – Global Warming WRONG Solar Cycle WRONG T record Originally from WSJ Article written by two chemists named Robinson

26. False Assertions: Sun – Global Warming Correct cycle Laut 2003

27. T Response After Major Eruptions

28. Natural and Anthropogenic Forcings

29. El Nino Southern Oscillation-ENSO

30. Neutral Walker Circulation Neutral

31. El Nino/La Nina State Flip-Flop

32. El Nino/La Nina Circulation Patterns Very Strong El Nino Strong La Nina

33. ENSO “Periodicity” El Niño years La Niña years

34. El Nino Global Impacts

35. El Nino Impact on Fish Normal El Nino

36. Climate History

37. 18O Ratios in Sediment and Ice Core

38. Pleistocene Glacial and Interglacials Reconstruction of land and sea ice 21,000 years ago (last glacial maximum) February July

39. Records of NH Glaciations Geological Records: glacial deposits, scarring, larger scale Cordilleran Ice Sheet Lake Missoula Spokane Floods (from Lake Missoula)

40. Milankovitch—Before sediment cores Predicts glacial and interglacial transitions based on variations in Earth’s orbit His results suggested many such transitions in ~ 1 million yrs (he was right) —at the time, no observable records show that many, so his work widely criticized Milutin Milankovitch

41. Milankovitch Continued While lacking patience for critics, he did not lack confidence Milutin Milankovitch “I do not consider it my duty to give an elementary education to the ignorant, and I have also never tried to force others to use my theory, with which no one could find fault.”

42. Orbital Forcing Summary Precession Tilt Eccentricity IPCC 2007

43. Currently NH summer takes place at aphelion, in about 12,000 years, NH summer will occur at perihelion. At this time, SH seasonality will be • stronger • weaker

44. Solar Insolation at 65N and Glaciation

45. Recent UW Research Time rate of change of ice volume and solar insolation

46. The Key For Glaciation + Ice Coverage Solar insolation in NH summer appears to be key maintaining glaciation. Ice sensitive to melting! Positive Feedback—Destabilizing Climate - T Albedo - Initial Forcing Weaker NH summer insolation + Same old ice-albedo feedback, just different initial forcing

47. Eccentricity: More to Less Circular

48. Obliquity: More or Less Seasonality

49. Precessional Cycle: Tilt and Eccentricity Current situation

50. Questions—In Class Activity • Given the behavior of CO2 and CH4 is there a positive or negative feedback with T? • Provide a feedback involving marine biota which might explain CO2’s behavior. • Suppose marine biota are the cause of CO2’s behavior, is this support for or against Gaia theory? • When’s the next glacial maximum? Do you think we’ll get there?