#goldschmidt2021 We contribute our work on dissipative dynamics and frequency distributions in river geochemistry and an update on the thermodynamics of planetary evolution.

Our work on thermodynamics and the Goldschmidt conference on geochemistry – well, that seems like an obvious match. But what we contribute is a little different, and the match is not quite so straightforward. What our perspective adds is (a) a focus on non-equilibrium thermodynamics and disequilibrium, and the processes that generate and dissipate this disequilibrium, and (b) a system‘s view which accounts for the environmental setting as well as the interactions and feedbacks within the Earth as an overarching thermodynamic system. Both of our contributions next week nicely illustrate these points and show how important it is to think „thermodynamics“ beyond its more narrow application to geochemical reactions.

Roberta, a PhD student from the University of Florence, presents our joint work with her advisor, Antonella Buccianti, as well as her colleagues at the Univ. of Florence on finding the answer to Is the dissipative behavior of river chemistry and catchment weathering dynamics reflected in their frequency distributions? in session „9k – Critical zone processes across space and time“. This question is motivated by the frequency distributions of geochemical elements, which often either show a normal or log-normal distribution, or a power-law distribution. How is the type of the distribution related to the thermodynamics of the system, particularly whether it is a dissipative system, or a system close to equilibrium? Roberta used extensive geochemical samples from the Arno river basin in central Italy, related it to the non-equilibrium thermodynamics of river water mixing, and found some really interesting results. Her presentation takes place on Monday, 5 July 2021, 17:10 in Room 04 (online). Her work is ready for write-up, so there’ll be more on this soon, in form of a manuscript and, hopefully, another blogpost.

Axel presents an update of the joint work with Adam Frank (Univ. Rochester) and Marina Alberti (Univ. Washington) on Thermodynamics of the planetary transitions from barren worlds to habitability and advanced technological societies in session „8f – Understanding the co-evolution of Earth’s interior, its surface, and its microorganisms„ (originally, it was submitted to a session on the Anthropocene, but apparently, this session got merged). This work is based on our paper Frank et al. (2017), which describes a basis to distinguish different planets regarding their processes that perform work and generate free energy, which reflects different forms of thermodynamic disequilibrium, and which results in different, dissipative dynamics, including human societies. This framework is currently extended to describe the general dynamics of such processes, the feedbacks involved, and how this links to concepts such as habitability and carrying capacity. His presentation is scheduled for Friday, 9 July 2021, 09:00 in Room 11 (online). More on this should come out sometime soon in form of a manuscript.

#vEGU21 Next week we’ll present our work on precipitation scaling, diurnal temperature range, offshore wind, and limits to vegetation productivity based on our thermodynamic Earth system view

Thermodynamics rules the world, as well as the science that we present at this year’s EGU General Assembly, which is, alas, virtual rather than in Vienna. It may not be obvious, and our contributions are spread across different sessions. But in the end, we follow the solar energy as it passes through the Earth system, seeking simple, physics-based explanations to simple phenomena: precipitation scaling with temperature found in observations, the diurnal temperature range across regions and vegetation types, also in observations, limits to offshore wind energy in the North sea and what these imply for renewable energy scenarios, and how the really low efficiency of photosynthesis fits to the notion of vegetation being optimal.

Continue reading “#vEGU21 Next week we’ll present our work on precipitation scaling, diurnal temperature range, offshore wind, and limits to vegetation productivity based on our thermodynamic Earth system view”

Why does wind energy become less efficient when used at larger scales? Basic physics explains this effect, starting with a very limited ability of the atmosphere to generate wind energy from radiation, as described in my new review just published.

Wind energy plays an important role in the transition to a carbon-neutral, sustainable energy system and is rapidly expanding. So it is a good time to ask how much wind energy there actually is, whether we get close to the limits anytime soon, and why the efficiency of wind energy must decline when used at larger scales. These are basic science questions: How, and why, does the atmosphere actually generate motion, how much does it generate, and how much of it can at most be used? These questions I address in a review paper just published in which I show that it does not take much physics to answer these.

Continue reading “Why does wind energy become less efficient when used at larger scales? Basic physics explains this effect, starting with a very limited ability of the atmosphere to generate wind energy from radiation, as described in my new review just published.”

Which factors make forests cooler: Evaporation or their high aerodynamic conductance? Our paper just published in HESS suggests that it is the latter.

Trees and plants moderate the Earth’s surface temperature. Generally, the cooling effect of vegetation is mainly attributed to the process of evapotranspiration. In our paper just published in HESS, we used observations to unravel the importance of evaporative cooling for short vegetation and forest in shaping diurnal variations in temperatures and found that, actually, it is not only evaporation that keeps the forests cool.

Continue reading “Which factors make forests cooler: Evaporation or their high aerodynamic conductance? Our paper just published in HESS suggests that it is the latter.”

More wind turbines should lead to less wind and less efficient wind turbines, but how to account for this? We showed that our simple spreadsheet KEBA model is about as good as complex WRF simulations to describe this effect.

Wind energy has seen a tremendous increase over the last decades, a trend that is likely to continue into the future with the transition towards a sustainable energy system. Yet, each wind turbine removes energy from the atmosphere, so the more wind turbines there are within a region, the more wind speeds should decline, making each turbine less efficient. This effect has clearly been shown by atmospheric simulation models (e.g., in our previous work), but this effect has typically not been accounted for in regional to continental wind energy resource estimates and energy scenarios for the future. The effect sounds complicated, so what should be done?

Continue reading “More wind turbines should lead to less wind and less efficient wind turbines, but how to account for this? We showed that our simple spreadsheet KEBA model is about as good as complex WRF simulations to describe this effect.”

Solar radiation is the main cause for diurnal variations on land. Looking at this slightly differently than how it is normally done helps to better understand observations and evaluate models of the land surface

My former postdoc, Maik Renner, just got his paper published in the Journal of Hydrometeorology, in which he evaluated the performance of common land surface models at the diurnal time scale using FluxNet observations. The evaluation was based on a simple concept that we developed in my group: that solar radiation is the main driver of the diurnal variation of variables that characterize the land-atmosphere system. This sounds trivial. Of course solar radiation is the dominant driver, so what novel insights can be gained from this view? Continue reading “Solar radiation is the main cause for diurnal variations on land. Looking at this slightly differently than how it is normally done helps to better understand observations and evaluate models of the land surface”

Does thermodynamics limit photosynthesis? It probably does, but not as you may think

Fig Leaf picturePhotosynthesis is the process which powers life on Earth.  It takes the energy contained in sunlight, uses carbon dioxide, and generates chemical energy that is stored in form of sugars and similar compounds that fuel the activity of the biosphere, including us humans.  And just as any other Earth system process, in doing so it follows the laws of thermodynamics.  But does thermodynamics also restrict the efficiency by which photosynthesis can use sunlight? 

Continue reading “Does thermodynamics limit photosynthesis? It probably does, but not as you may think”

Are you looking for a stimulating Postdoc opportunity? Our group has a position open, applying thermodynamics and optimality to Earth system science.

I have an opening for a Postdoc position available in my group that is rather flexible and provides a lot of freedom because it is unattached to any research project (it is the succession of my co-worker Maik Renner, who advanced to a permanent position elsewhere).  I would like the research to broadly focus on advancing the application of thermodynamics and optimality principles to Earth system science, but the concrete topic is up to you.  So if you are curious to learn more about thermodynamics and how to apply it, I’d like you to think about a topic and apply!  The formal details are provided on our homepage here. Continue reading “Are you looking for a stimulating Postdoc opportunity? Our group has a position open, applying thermodynamics and optimality to Earth system science.”

Does global warming behave the same on rainy and sunny days? No, it doesn’t, and our new JGR paper explains why.

Global warming, the increase in near-surface temperature due to the enhanced greenhouse effect at global scale, has clearly been reflected in observations over the last 50 years. However, the severities of warming in different regions and different period differs a lot. Scientists have considered many factors which may contribute to shape the temperature trends.  For example, our ESD paper explained the stronger temperature trends over land compared to oceans by the different ways by which the diurnal variation in solar radiation is buffered on land and ocean. Here we introduce another simple but significant factor, sunny and rainy days. Continue reading “Does global warming behave the same on rainy and sunny days? No, it doesn’t, and our new JGR paper explains why.”

Do roughness changes of tropical deforestation affect surface energy balance partitioning? No, they don’t. That’s what we found when we estimated the effects from first principles.

Cutting down tropical rainforests and replacing them with soybean fields alters how the land surface functions, and this affects the atmosphere.  Rainforests have a heterogeneous canopy that absorbs sunlight very well and is aerodynamically rough, and they have deep-reaching root systems that allow them to draw water from deep within the soil, especially during the dry season when water input by precipitation is limited.  When trees are cut down and replaced by soybean fields, these physical aspects of the land surface are changed, thus impacting how the absorbed solar energy is partitioned at the surface, and how this energy is transferred into the overlying atmosphere.  Tropical deforestation is one of the many aspects of global change that has been dealt with over the last decades, evaluated with observations and climate models, so what else can add new insights?  And what can these insights be used for? Continue reading “Do roughness changes of tropical deforestation affect surface energy balance partitioning? No, they don’t. That’s what we found when we estimated the effects from first principles.”