The Long-Term Atmosphere: Connections with the Earth’s Magnetic Field

This book investigates the billion-year takeover of planet Earth by its organisms and ecosystems. This chapter examines the effects of the Earth’s magnetic field on the long-term atmosphere and the resulting consequences for organisms. The chapter focuses in turn on: the succession of phases of the atmosphere, and the corresponding Earth System conditions; the use of the magnetic field by wildlife and humans; the magnetic fields of Earth and other astronomical bodies in the Solar System; the contribution of the magnetic field to the takeover of Earth by organisms in aquatic environments and on continents; and the use by researchers of magnetic fields fossilized in rocks to explore ancient Earth. The chapter considers the mechanisms by which the Earth’s magnetic field is generated, and how the interactions between the magnetic fields of Earth and the Sun contributed to protect both the atmosphere and the water of the planet. The magnetic field protects the Earth’s atmosphere, and the latter shields the liquid water from loss to space. The presence of the liquid ocean was a key factor in the development of ecosystems and the build-up of large biomasses. In addition, organisms on continents are largely protected from direct hits of cosmic rays by the magnetic field which both shields the atmosphere from most cosmic rays and protects the atmosphere whose thickness absorbs most of the cosmic radiation that passes the shield. The chapter ends with a summary of key points concerning the interactions between the Solar System, Earth, the long-term atmosphere, and organisms.