This interdisciplinary session focuses on the multiple impacts of solar and geomagnetic variability (including galactic cosmic rays) on the terrestrial weather and climate. This includes solar radiative variability, solar energetic particles, galactic cosmic rays, and electron precipitations from radiation belts. Both short transients such as solar flares and geomagnetic storms, and long-term trends will be considered. Special attention will be paid to their impacts on the upper, middle and lower atmosphere.