Sources and sinks of climate entropy

Goody, R. M.

doi:10.1256/smsqj.56619

Cited by 51 publications

(111 citation statements)

References 4 publications

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“…The estimates shown in Fig. 4 are mostly derived from heat fluxes and their respective temperature gradients and are taken from previous estimates [42][43][44]. The dominant dissipative process is the absorption of solar radiation at Earth's much lower temperatures of about 280 K compared to the emission temperature of the Sun of about T sun = 5760 K. Entropy production by absorption contributes more than 90% to the planetary entropy production of about 918 mW m −2 K −1 .…”

Section: The First and Second Laws And The Earth Systemmentioning

confidence: 99%

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Life, hierarchy, and the thermodynamic machinery of planet Earth

Kleidon

2010

Physics of Life Reviews

150

126

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Throughout Earth's history, life has increased greatly in abundance, complexity, and diversity. At the same time, it has substantially altered the Earth's environment, evolving some of its variables to states further and further away from thermodynamic equilibrium. For instance, concentrations in atmospheric oxygen have increased throughout Earth's history, resulting in an increased chemical disequilibrium in the atmosphere as well as an increased redox gradient between the atmosphere and the Earth's reducing crust. These trends seem to contradict the second law of thermodynamics, which states for isolated systems that gradients and free energy are dissipated over time, resulting in a state of thermodynamic equilibrium. This seeming contradiction is resolved by considering planet Earth as a coupled, hierarchical and evolving non-equilibrium thermodynamic system that has been substantially altered by the input of free energy generated by photosynthetic life. Here, I present this hierarchical thermodynamic theory of the Earth system. I first present simple considerations to show that thermodynamic variables are driven away from a state of thermodynamic equilibrium by the transfer of power from some other process and that the resulting state of disequilibrium reflects the past net work done on the variable. This is applied to the processes of planet Earth to characterize the generation and transfer of free energy and its dissipation, from radiative gradients to temperature and chemical potential gradients that result in chemical, kinetic, and potential free energy and associated dynamics of the climate system and geochemical cycles. The maximization of power transfer among the processes within this hierarchy yields thermodynamic efficiencies much lower than the Carnot efficiency of equilibrium thermodynamics and is closely related to the proposed principle of Maximum Entropy Production (MEP). The role of life is then discussed as a photochemical process that generates substantial amounts of chemical free energy which essentially skips the limitations and inefficiencies associated with the transfer of power within the thermodynamic hierarchy of the planet. This perspective allows us to view life as being the means to transform many aspects of planet Earth to states even further away from thermodynamic equilibrium than is possible by purely abiotic means. In this perspective pockets of low-entropy life emerge from the overall trend of the Earth system to increase the entropy of the universe at the fastest possible rate. The implications of the theory are discussed regarding fundamental deficiencies in Earth system modeling, applications of the theory to reconstructions of Earth system history, and regarding the role of human activity for the future of the planet.

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Section: The First and Second Laws And The Earth Systemmentioning

confidence: 99%

“…Fluxes J are given in units of W m −2 , associated temperatures T in K, solid angle Ω in radians, and entropy production σ in mW m −2 K −1 . After [26] with numbers based on [42][43][44].…”

Section: The First and Second Laws And The Earth Systemmentioning

confidence: 99%

Life, hierarchy, and the thermodynamic machinery of planet Earth

Kleidon

2010

Physics of Life Reviews

150

126

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“…The global mean irreversible entropy sources in the real atmosphere [50,25] are estimated to be of order 20 mW m À2 K À1 for moist processes and of order 5-10 mW m À2 K À1 for turbulent and dissipative processes. (It is difficult to re-express these values as timescales because it is not obvious what to take as the reference value for entropy.)…”

Section: Entropymentioning

confidence: 99%

Some conservation issues for the dynamical cores of NWP and climate models

Thuburn

2008

Journal of Computational Physics

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“…Work so far (Wong et al 2006) has involved the use of anomaly data, which are less sensitive to absolute error. Despite this, we can see that it may be possible to provide a meaningful test of the validity of a model of the climate system if we demand that it satisfies observed TOA SW, LW, and net fluxes [F Y SW (x, y, t), F Y LW (x, y, t) and F N (x, y, t)] and possibly even limitations on the entropy production rate associated with all the internal processes that link F Y SW and F [ LW (Goody 2000).…”

Section: Introductionmentioning

confidence: 99%

On the Variability of the Global Net Radiative Energy Balance of the Nonequilibrium Earth

Harries

Belotti

2010

Journal of Climate

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Recent observations and model studies of the earth's radiative energy balance have focused attention on the earth's top of atmosphere (TOA) energy balance. This is the balance between the shortwave energy absorbed by the earth, which is represented by a spatially and temporally averaged absorbed flux F Y , and the emitted longwave energy, which is represented by the corresponding averaged emitted flux F [ . The TOA average net flux F N is defined as the difference between the two over the averaged area and time, which may be a local, regional, or global average. A global nonzero net flux represents a measure of imbalance between the energy being absorbed and emitted by the earth for the time interval in question. It is of interest to ask what the natural variability of the net flux might be and whether, during times of climate change, signals of important climate change processes might be detected against this natural background variation; examples of these signals include evidence of ocean heat storage, the effects of El Niñ o, and the radiative effects of volcanic eruptions. In this paper, the authors review the significance of the net flux, survey the observational evidence from a range of satellite instruments over several decades, and analyze some of the most recent observations from the Clouds and the Earth's Radiant Energy System (CERES) program to determine what signals and what natural variability might be expected in the TOA net flux. Based on this analysis, the use of broadband radiation measurements for global climate change studies can be assessed.

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Sources and sinks of climate entropy

Cited by 51 publications

References 4 publications

Life, hierarchy, and the thermodynamic machinery of planet Earth

Life, hierarchy, and the thermodynamic machinery of planet Earth

Some conservation issues for the dynamical cores of NWP and climate models

On the Variability of the Global Net Radiative Energy Balance of the Nonequilibrium Earth

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