Liquid Water: Connections with the Outer Reaches of the Solar System

Abstract

This book investigates the billion-year takeover of planet Earth by its organisms and ecosystems. This chapter investigates the special importance of water for organisms and ecosystems, including key processes in their cells. It considers successively: the types of water at the Earth’s surface; the sources of the Earth’s water in the Solar System; the different abundances and histories of water on Earth, Venus and Mars; the physical and chemical properties of water, and the phases of water on Earth, Venus and Mars; and the characteristics of Earth that keep most of the Earth’s water in liquid form. The latter include the Earth’s mass and distance from the Sun, the storage and release of heat by the lower atmosphere, the fast rotation of the planet, and the small value of the axial tilt stabilized by the existence of the Earth-Moon system. The chapter also examines the presence of liquid water during the history of the planet, and describes the Earth’s water cycle. The early formation of a planet-wide ocean, in which atmospheric carbon dioxide (CO₂) was rapidly trapped into solid calcium carbonate (CaCO₃), largely determined the fate of Earth. Indeed, the concentration of atmospheric CO₂ reached after the formation of the ocean contributed to create a greenhouse effect that has since maintained the temperature of the planet at a level compatible with the presence of liquid water. The chapter ends with a summary of key points concerning the interactions between the Solar System, Earth, water, and organisms.

Figure Credits

Fig. 5.1 Original. Figure 5.1 is licensed under CC BY-SA 4.0 by Philippe Bertrand, Louis Legendre and Mohamed Khamla.

Fig. 5.2 Original. Figure 5.2 is licensed under CC BY-SA 4.0 by Philippe Bertrand, Louis Legendre and Mohamed Khamla.

Fig. 5.3 Modified after http://planet-terre.ens-lyon.fr/article/eau-glace-pression.xml. With permission from Prof. Olivier Dequincey, Ecole Normale Supérieure de Lyon, France.

Fig. 5.4 This work, Fig. 5.4, is a derivative of https://commons.wikimedia.org/wiki/File:3D_model_hydrogen_bonds_in_water.svg by Qwerter at Czech wikipedia https://cs.wikipedia.org/wiki/Wikipedista:Qwerter, in the public domain. I, Mohamed Khamla, release this work in the public domain.

Fig. 5.5 Original. Values calculated using the equation given in https://en.wikipedia.org/wiki/Atmospheric_pressure. Figure 5.5 is licensed under CC BY-SA 4.0 by Philippe Bertrand, Louis Legendre and Mohamed Khamla.

Fig. 5.6 Original. Figure 5.6 is licensed under CC BY-SA 4.0 by Philippe Bertrand, Louis Legendre and Mohamed Khamla.

Fig. 5.7 This work, Fig. 5.7, is a derivative of https://commons.wikimedia.org/wiki/File:Watercyclesummary.jpg by John Evans and Howard Periman, USGS, in the public domain. I, Mohamed Khamla, release this work in the public domain.