System Earth changes continuously. Variations of Earth’s interior, the atmosphere, the oceans, and near-Earth space give rise to changes in global fields, particularly in Earth’s magnetic and gravity fields. The underlying processes can be identified and studied through monitoring and analysis of fundamental geomagnetic and gravity parameters. The main focus of this Priority Programme is to quantify terrestrial transport mechanisms and solar-terrestrial interactions. The research programme builds on data from satellites on low-Earth orbits, such as CHAMP, GRACE, GOCE, and Swarm, the latter being of particular importance due to its multi-satellite constellation aspect.