Solar Output Variability.- Assessing Solar Variability.- Solar Variability of Possible Relevance for Planetary Climates.- Measurement of Total and Spectral Solar Irradiance.- Solar Irradiance Variability Since 1978.- Solar Variability Over the Past Several Millennia.- Solar and Heliospheric Modulation of Galactic Cosmic Rays.- What Do Cosmogenic Isotopes Tell Us about Past Solar Forcing of Climate?.- Tropospheric Aerosols, Radiation Budget, and Changes.-...