The Natural Greenhouse Effect: Connections with Geological Activity

This book investigates the billion-year takeover of planet Earth by its organisms and ecosystems. This chapter deals with the connections between the geological activity of Earth and the natural greenhouse effect. It addresses: the habitability of the planet and the long-term natural greenhouse effect; the tectonic activity of Earth and its effects on the long-term functioning of the Earth System; the effects of tectonically-driven carbon recycling on climate variations; and the feedback of climate into tectonic activity. The chapter describes the growth and destruction of the oceanic and the continental crust, and their effects on the recycling and sequestration (long-term storage in natural reservoirs) of carbon and other chemical elements used by organisms. It examines the chemical alteration of continental calcium carbonate rocks (CaCO3) and continental and seafloor silicate rocks (CaSiO3), the latter being a key process in a negative feedback loop that controls the concentration of atmospheric CO2 in the long-term, and thus the functioning of the Earth System. It also considers different types of volcanic activity, which exert different effects on the global climate at different timescales. The chapter ends with a summary of key points concerning the interactions between the Solar System, Earth, the natural greenhouse effect, and organisms. It is explained that over the past 4 billion years, the global coupling of the Earth’s carbon-recycling processes has maintained a long-term moderate greenhouse effect. This created globally suitable temperatures for organisms, which allowed them to build huge biomasses and thus take over the Earth System.