1. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Changes in Radiative Forcing Primary Source: IPCC WG-I Chapter 2 - Changes in Atmospheric Constituents and in Radiative Forcing

2. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Key Findings 1.Extremely likely (> 95%) that humans have exerted a substantial warming influence on climate since 1750. 2.Likely (> 66%) that the human influence by radiative forcing is at least 5 times greater than solar influence since 1750. 3.Exceptionally unlikely (< 1%) that solar + volcanic radiative forcing for 1950-2005 was comparable to anthropogenic radiative forcing.

3. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Major Types of Radiative Forcings Changes in … Greenhouse Gases Greenhouse Gases Aerosols (particles) Aerosols (particles) Surface albedo Surface albedo Contrails Contrails Solar variability Solar variability Volcanic activity Volcanic activity

4. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Radiative Forcing: Balanced State Radiative Balance Radiative-Dynamic Balance

5. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Radiative Forcing Change in net radiative energy flux at the tropopause with … Change in net radiative energy flux at the tropopause with … (a) stratospheric temperatures readjusted to radiative equilibrium (b) surface and tropospheric temperatures and state held fixed at original values (Ramaswamy et al., 2001)

6. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Carbon Dioxide (CO 2 ) Pre-industrial: ~ 280 ppm Sources: 1.Fossil fuels 2.Cement production 3. Deforestation 4. Biomass burning

7. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) CO 2 Emissions 13 C/ 12 C: Atmosphere > Terrestrial Sources O 2  as CO 2  : - Combustion - Plant respiration/photosynthesis

8. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Methane (CH 4 ) NOAA Global Monitoring Division (GMD) Advanced Global Atmospheric Gases Experiments (AGAGE) Sources: 1.Biogenic: -Wetlands -Rice -Biomass burning -Ruminants 2.Fossil fuel mining and distribution 3. Living vegetation? Mt. Pinatubo? Economic Incentives? Warm 1998?

9. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Nitrous Oxide (N 2 O) Sources: 1.Coastal areas: -continental shelves - estuaries - rivers 2.Land processes

10. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Halocarbons Small amounts, but effective absorbers of infrared radiation Factors: 1.Industrial processes 2.Partly regulated by Montreal Protocol

11. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Other Gases Stratospheric Ozone Stratospheric Ozone Tropospheric Ozone Tropospheric Ozone Stratospheric Water Vapor Stratospheric Water Vapor

12. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Aerosol Effects

13. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Aerosol Types Sulphate Sulphate Organic Carbon from Fossil Fuels Organic Carbon from Fossil Fuels Black Carbon from Fossil Fuels Black Carbon from Fossil Fuels Biomass Burning Biomass Burning Nitrate Nitrate Mineral Dust Mineral Dust

14. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Aerosol Distributions Biomass Burning Optical Depth ~ Radiative “Thickness” White = measurement not possible Mineral Dust Industrial Sea Salt

15. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Land Use Changes Albedo Differences Forest < Cropland Snow-covered forest < Snow-covered cropland

16. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Other Surface Effects Black Carbon on Snow/Ice Black Carbon on Snow/Ice Land-Use Changes on Surface Fluxes Land-Use Changes on Surface Fluxes Anthropogenic Water Vapor Release Anthropogenic Water Vapor Release Anthropogenic Energy Release Anthropogenic Energy Release CO 2 Influence on Plant Physiology CO 2 Influence on Plant Physiology

17. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Solar Heating: Change Variability due to 1. Changes in sunspots and faculae 2. Changes in solar diameter?

18. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Reconstructed Solar Heating

19. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Volcanic Aerosols

20. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Time Evolution of Forcing (Representative GCM)

21. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) Net RF: 1750 to 2005

22. (Mt/Ag/EnSc/EnSt 404/504 - Global Change) Radiative Forcing (from IPCC WG-I, Chapter 2) END Changes in Radiative Forcing