Working at the limit: How thermodynamics shapes the Earth system – A series of talks in India 2023 – Here is the link to slides and more material.

We just completed a series of lectures in India on the central importance of thermodynamics and limits in Earth system science, with examples from climatology, global warming, life, sustainability and renewable energy. Here is the link to the slides and some background material, in case you missed it, want to check or are interested in more information.

After a first trip in 2019 just before the Corona pandemics started, we visited India again. Sarosh and I travelled to IIT Bombay, IISc in Bengaluru, BHU in Varanasi, Delhi University, Kashmir University, and IUST, having discussions and talks on thermodynamics, Earth system science, climate change, renewable energy and what it implies for a sustainable future. In this blogpost we share the slides (see below) and some links with brief comments on related literature that was referred to in the slides or in the talks. We are deeply grateful for Vinod Gaur for arranging this trip and for the local hosts for their hospitality and great interactions!

workingatthelimit_india23 Download

A video recording of the talk given at IUST is available on youtube.

Thermodynamic background

The most up-to-date summary of how thermodynamics and optimality apply to the Earth system is described in this manuscript (see also this talk on youtube), which is not published yet (it is in revision). It is based on previous versions that describe this view of the Earth system published in 2010 and 2012 that are less specific, but nevertheless describe the basic picture. I have also written a book although it is not open access.

Applications to climate, hydrology, and global climate change

We have several publications where we applied maximum power to climatology, hydrology and global climate change.

The first publications on maximum power were the more conceptual paper published back in 2013, its application to land surface energy balance partitioning in 2014, globally over land and ocean (Dhara et al. 2016), to the diurnal cycle on land (Kleidon and Renner 2018) and over land cover change in Amazonia (Conte et al., 2019). In Ghausi et al 2022 we used this approach to remove the effects of cloud cooling to infer the sensitivity of precipitation to temperature over India (see also this blogpost).

We have applied our approach to global climate change to estimate the sensitivity of hydrologic cycling (Kleidon and Renner 2013b), the transient response (Kleidon et al 2015), and the different sensitivities across ocean and land (Kleidon and Renner 2017).

Applications to the biosphere

My original interest in thermodynamics was stimulated by the so-called Gaia hypothesis, related to the general question of how the biosphere affects the physical conditions of the Earth system. Do biotic effects affect climate in any particular direction, and, if so, why?

This eventually brought me to entropy and the second law of thermodynamics. My first paper on this is focused more on the biosphere (Kleidon 2002, ask me for a reprint if you don’t have access), and then it continued with a focus on entropy production (Kleidon 2004). My latest thinking on the Gaia hypothesis from a thermodynamic perspective is given in this book chapter (Kleidon (2023), blogpost here).

There is also more recent work on the thermodynamics of photosynthesis (Kleidon 2021, blogpost here), and on its implication for sustainability (Kleidon 2021, blogpost here; Kleidon 2023), with Kleidon (2023) including the estimates of how vegetation pushes the limits of the biosphere by access to soil water.

Applications to renewable energy

A practical application of a thermodynamic Earth system perspective is that it allows us to evaluate limits to renewable energy. This is because renewable energy typically concerns forms of energy that were generated from work being performed from sunlight, directly or indirectly.

A general paper on how sunlight generates energy that can be used as renewable energy is given in Kleidon et al (2016). We have also done some work on hypothetical limits on wind energy use using complex climate models, but also simple models based on energy (Miller et al, 2011, 2015, 2016). We recently developed a simple budget model to estimate regional wind energy resource potentials (Kleidon and Miller 2020), which was applied to offshore wind energy in the North sea (Agora Energiewende et al. 2020, blogpost here). A recent review article summarizes the thermodynamic limits of large-scale motion and the limits to wind energy (Kleidon 2021, blogpost here).