Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach

Abstract

Abstract. Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life's ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes.

Thermodynamic Limits of the Critical Zone and their Relevance to Hydropedology

“…the potential energy associated with surface water at a certain elevation fed by precipitation) until it ultimately ends up in a form of dissipative heating. (From Kleidon (2010), and Dyke et al, 2011). This is illustrated in Fig.…”

“…These estimates are given here merely for providing an order of magnitude, whereas the actual numbers are quite uncertain. This estimate is based on the gross primary productivity of the terrestrial biosphere of about 120 GtC/yr, which reflects the conversion of the free energy of solar radiation into the chemical free energy associated with sugars and the release of oxygen (Dyke et al, 2011;Kleidon, 2010). The first line in Table 2 describes the generation of chemical free energy from solar radiation by photosynthesis.…”

Quantifying drivers of chemical disequilibrium: theory and application to methane in the Earth's atmosphere

“…There are many examples of physical and chemical disequilibria in the Earth system (Dyke et al, 2011;Kleidon, 2012). Most of the important disequilibria in the Earth system are ultimately driven by the difference in the radiative temperature between the incoming, solar radiation at around 6000 K, which corresponds to an import of radiative energy of low entropy, and the radiative temperature of the radiation emitted from Earth at around 255 K, which corresponds to an export of radiative energy of high entropy.…”

Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

“…This trade-off shapes the value of the gradient in geopotential φ/L that drives runoff and sediment transport. The third model aims to demonstrate that this trade-off results in a state of maximum power associated with the lifting of continental mass (after Dyke et al, 2011). To start, we consider the mass balance of sediments m s in steady state (Eq.…”