This interdisciplinary session covers various aspects of external forcing (such as solar radiative variability, solar energetic particles, galactic cosmic rays, and electron precipitations from radiation belts...) and geomagnetic forcing on the terrestrial atmosphere, weather and climate (tides, planetary waves, gravity waves, chemistry, neutral-ion coupling...) and on the interaction of the various processes. The temporal behaviour of the Sun-Earth system will be studied on timescales covering short transients such as solar flares and geomagnetic storms to the 11-yr solar cycle and long-term trends. We encourage contributions related to the Climate and Weather of the Sun-Earth System (CAWSES) program initiated by SCOSTEP and those related to the European COST ES 1005 action "Towards a more complete assessment of the impact of solar variability on the Earth's climate". The contributors will be invited to submit their contribution to the Journal of "Space Weather and Space Climate".