Climate Dynamics Starts with the Sun NASA Image From Wallace and Hobbs r = 6.96x10 8 m T=5780K Photosphere Sunspots Faculae Figure 1.1

Integration of Intensity over a Hemisphere to Get Net Downward Energy Flux Density in W/m 2. 1 m 2 area We want Watts per m 2. Figure 1.2

Sun and Earth Blackbody Spectra, Trace Gas Absorption Lines From Wallace and Hobbs Figure 1.3

Climate Dynamics Starts with the Sun NASA Image From Wallace and Hobbs r = 6.96x10 8 m T=5780K Photosphere Sunspots Faculae Figure 1.4

The Earth’s Orbit is Elliptical Figure 1.5

Measurement of the Solar Constant from Satellite is Difficult Figure 1.6 Improved Instrument More Scattering, Higher Irradiance Measured Kopp and Lean (2010)

Recent Solar Constant Measurements from the SORCE Experiment Figure 1.7 Courtesy of Greg Kopp (LASP)

Climate Dynamics Starts with the Sun NASA Image From Wallace and Hobbs r = 6.96x10 8 m T=5780K Photosphere Sunspots Faculae Figure 1.8

11-Year Sunspot Cycle Indicates Variations in Solar Luminosity Percent Area of Photosphere Covered by Sunspots Fraction Area of Entire Photosphere Covered by Sunspots Yellow >1% Figure 1.9

Direct Measurements of Solar “Constant” IPCC 2013 Satellite Retrievals Figure 1.10

Solar “Constant” Reconstructions Suggest Stronger Longer-Term Variations IPCC 2007 Figure 1.11

IPCC 2013 Figure 1.12 Solar Forcing Since 1750 is Relatively Small Compared to Other External Perturbations to the Climate System. *Volcanic Ignored.