Abstract
Abstract. This is a comment on Michaelian and Simeonov (2015). Michaelian and Simeonov formulate the leading thought in their article: “The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate”. I shall in the following try to provide some information that might help to clarify whether this is correct.
Highlights
Already in the first sentence of their abstract Michaelian and Simeonov formulate the leading thought in their article: “The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate”
The geometric spectral albedo of the resulting haze depends on the CH4/CO2 ratio: the higher it is, the higher the peak wavelength for the reflectance, and the higher the albedo maximum (Arney et al, 2016)
For a CO2 pressure of 0.018 bar, at total pressure of 1 bar, and a CH4/CO2 ratio of 0.21, the haze has a broad reflectance band with a maximum albedo of 0.22 at 750 nm. These values are very sensitive to the CH4/CO2 ratio
Summary
Already in the first sentence of their abstract Michaelian and Simeonov formulate the leading thought in their article: “The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate”. As long as light travels freely in space, there is no change in the entropy associated with it. If it is scattered, entropy is increased. If we consider only the non-absorbed fraction of the light, a surface reflecting light in a diffuse way (i.e., non-specularly) will increase entropy by scattering, not by changing the photon number; there is, in principle, no difference between non-living substances (e.g., pure sand) and organisms in this respect. An absorbing surface on Earth will eventually cause incident radiation to be converted to diffuse radiation of an in-
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