2024/10/22 by Axel Kleidon · 1 voice
Earth and Planetary Sciences · Physics and Astronomy · #Earth Systems and Cosmic Evolution #Space Science and Extraterrestrial Life #Advanced Thermodynamics and Statistical Mechanics
paper · doi:10.1016/j.plrev.2024.10.009
openalex publication_date 2024/10/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
• Paper provides an update to Kleidon's [ 14 ] paper on "Life, hierarchy, and the thermodynamic machinery of planet Earth". • Life operates within a hierarchy of energy transformations within the Earth system that are governed by thermodynamics and limits. • This thermodynamic Earth system framework predicts climate processes like temperature and hydrological cycles very well. • Biospheric activity is constrained by transport, not energy conversion efficiencies. • Life evolves to push limits that involve interactions with the planet, shaping the planetary environment. Life is a planetary feature that depends on its environment, but it has also strongly shaped the physical conditions on Earth, having created conditions highly suitable for a productive biosphere. Clearly, the second law of thermodynamics must apply to these dynamics as well, but how? What insights can we gain by placing life and its effects on planetary functioning in the context of the second law? In Kleidon (2010), I described a thermodynamic Earth system perspective by placing the functioning of the Earth system in terms of the second law. The Earth system is represented by a planetary hierarchy of energy transformations that are driven predominantly by incoming solar radiation, these transformations are constrained by the second law, but they are also modified by the feedbacks from various dissipative activities. It was then hypothesised that life evolves its dissipative activity to the limits imposed by this hierarchy and evolves feedbacks aimed at pushing these limits to higher levels of dissipative activity. Here I provide an update of this perspective. I first review applications to climate and global climate change to demonstrate its success in predicting magnitudes of physical processes, particularly regarding temperatures, heat redistribution and hydrological cycling. I then focus on the limits to dissipative activity of the biosphere. It would seem that the limitations by thermodynamics act indirectly by imposing limitations associated with transport and material exchange. I substantiate this interpretation and discuss the broader implications for habitability, the emergence and evolution of life, and the contemporary biosphere.