Alan Robock Department of Environmental Sciences

1. Lecture 13, 10/23/14 Climate Dynamics11:670:461 Alan Robock Department of Environmental Sciences Rutgers University, New Brunswick, New Jersey USA robock@envsci.rutgers.edu http://envsci.rutgers.edu/~robock

6. 400 From IPCC AR4 Technical Summary

7. Box 8.1: Definition of Radiative Forcing (RF) and Effective Radiative Forcing (ERF) The two most commonly used measures of radiative forcing in this chapter are the radiative forcing (RF) and the effective radiative forcing (ERF). RF is defined, as it was in AR4, as the change in net downward radiative flux at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, while holding surface and tropospheric temperatures and state variables such as water vapor and cloud cover fixed at the unperturbed values. Chapter 8, AR5, WG1

8. Box 8.1: Definition of Radiative Forcing (RF) and Effective Radiative Forcing (ERF) (continued) ERF is the change in net top-of-the-atmosphere downward radiative flux after allowing for atmospheric temperatures, water vapour, and clouds to adjust, but with surface temperature or a portion of surface conditions unchanged. While there are multiple methods to calculate ERF, we take ERF to mean the method in which sea surface temperatures and sea ice cover are fixed at climatological values unless otherwise specified. Land-surface properties (temperature, snow and ice cover and vegetation) are allowed to adjust in this method. Hence ERF includes both the effects of the forcing agent itself and the rapid adjustments to that agent (as does RF, though stratospheric temperature is the only adjustment for the latter). Chapter 8, AR5, WG1

9. Different calculations of radiative forcing, Fig. 8.1 IRF = Instantaneous radiative forcing, ERF = Effective Chapter 8, AR5, WG1

10. Chapter 8, AR5, WG1

11. Chapter 8, AR5, WG1

12. Chapter 8, AR5, WG1

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14. Chapter 8, AR5, WG1

15. Figure 8.9: Change in TOA SW flux [W m–2] following the change in albedo as a result of anthropogenic Land Use Change for three periods (1750, 1900 and 1992 from top to bottom). By definition, the RF is with respect to 1750, but some anthropogenic changes had already occurred in 1750. The lower right inset shows the globally averaged impact of the surface albedo change to the TOA SW flux (left scale) as well as the corresponding RF (right scale) after normalization to the 1750 value. Based on simulations by Pongratz et al. (2009). Chapter 8, AR5, WG1

16. Chapter 8, AR5, WG1

17. Chapter 8, AR5, WG1

18. Chapter 8, AR5, WG1

19. Chapter 8, AR5, WG1

20. Chapter 8, AR5, WG1

21. Figure 8.17: RF bar chart for the period 1750–2011 based on emitted compounds (gases, aerosols or aerosol precursors) or other changes. Chapter 8, AR5, WG1

22. Figure 8.18: Time evolution of forcing for anthropogenic and natural forcing mechanisms. Bars with the forcing and uncertainty ranges (5–95% confidence range) at present are given in the right part of the figure. For aerosol the ERF due to aerosol-radiation interaction and total aerosol ERF are shown. Chapter 8, AR5, WG1

23. Start with temperature increase, e.g., from more CO2 – + + + – + – – – Temperature Feedbacks Robock, Alan, 1985: An updated climate feedback diagram. Bull. Amer. Met. Soc., 66, 786-787. External forcing

24. Poisson d’Avril = April Fool Of course! This is the best thing since sliced ​​baguettes! http://www.realclimate.org/index.php/archives/2007/04/the-sheep-albedo-feedbacki/