1. Topics to be covered today Regarding Global Effects HNRT 228 Spring 2016
Future CO2 Forcing
Climate Sensitivity – Feedbacks
Natural Short and Long-term Forcings
Global Warming Impacts

2. iClicker Question
There has been much talk on television news about the severe weather conditions recently across the country. Is this an indication of global warming?
A Yes
B No

3. Kaya Identity Model
kaya identity model

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

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

6. Committed to Warming: Time Response

7. A Long View of Fossil Fuel Perturbation

8. Climate Sensitivity-All about Feedbacks
is climate sensitivity parameter
 units: K “per” W/m2
  determined by feedbacks!

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

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

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

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

13. 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

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

15. 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
DMS - Dimethylsulfide

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

17. Aircraft emit particles (and particle precursors) which can nucleate clouds. This activity gives rise to a
A Positive radiative forcing
B Negative radiative forcing

18. Aviation Contrails—Positive Forcing
October 2004

19. 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

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

21. Predicted Changes in Cloud Forcings
IPCC 2007

22. Sunspots – Cyclic Changes in Solar Output

23. ~11 year Sunspot Cycle

24. Radiative Forcing by Solar Cycle

25. The solar cycle forcing has increased from -0. 1 to 0
The solar cycle forcing has increased from -0.1 to 0.2 W/m2 since This forcing can explain ____ of 1oC increase in global Avg. T since 1900
A %
B %
C < 30%

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

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

28. T Response After Major Eruptions

29. Natural and Anthropogenic Forcings

30. El Nino Southern Oscillation-ENSO

31. Neutral Walker Circulation

32. El Nino/La Nina State Flip-Flop

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

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

35. El Nino Global Impacts

36. El Nino Impact on Fish
Normal
El Nino

37. Climate History

38. 18O Ratios in Sediment and Ice Core

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

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

41. 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

42. 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.”

43. Orbital Forcing Summary
Precession
Tilt
Eccentricity
IPCC 2007

44. 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
A stronger
B weaker

45. Solar Insolation at 65N and Glaciation

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

47. The Key For Glaciation
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 +
Ice Coverage +
Same old ice-albedo feedback, just different initial forcing

48. Eccentricity: More to Less Circular

49. Obliquity: More or Less Seasonality

50. Precessional Cycle: Tilt and Eccentricity
Current situation

51. 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?