Bits, blog posts, and links on thermodynamics and Earth system science from Axel Kleidon's research group at the Max-Planck-Institute for Biogeochemistry in Jena, Germany
Thermodynamics – sounds complicated? It should not! Because it deals with one of the most central aspects of how the Earth system functions: that processes perform work! And this work maintains the dynamics of the Earth system, shaping climate, the hydrologic cycle, and other systems. I am back in Firenze giving two lectures on 4th and 5th of June, also accessible online. More infos in this blogpost.
Kernenergie ist nicht tot zu kriegen, zumindest bei manchen Politikern, und bei dem, was dann in den Medien erscheint. Es werden wundersame neue Technologien versprochen, Investoren fluten neue Startups mit Geld — aber die Realität sieht ganz anders aus. Und ob man es nun mag oder nicht: nur die Realität zählt, sie zeigt klar, wohin es bei der Energieversorgung geht. Und sie ergibt physikalisch Sinn. Darüber sprechen Harald Lesch und ich im neuen Video am Küchentisch. Mehr Hintergrund auch hier im Blogpost.
Each year geoscientists migrate to Vienna in the spring. Because it is a nice time to meet, and the General Assembly of the European Geosciences Union takes place, this time in early May, from 04 May to 08 May 2026. We are thrilled to be there, meet colleagues and friends, and discuss science. Our group will be involved in quite a few presentations – check out this blogpost for more infos.
Continue reading “#EGU26: Vienna again with maximum power ahead! We will talk about the maximum power limit and land-atmosphere interactions, mountain warming trends, VPD and its trends, precipitation, and soil dynamics.”
Again we were in India in March. This year, we visited Sarosh at IIT Kanpur with a short course on “Thermodynamics for Climate, Water, and Urban Systems sustainability”, discussed thermodynamics, maximum power, glaciers and climate change in Pune at IITM and IISER, and visited IIT Bombay for a workshop and seminar. And talked a lot with colleagues and students. More in this blogpost.
Continue reading “Touring India 2026: Short courses/workshops/talks at Kanpur, Pune, and Bombay to discuss how many features of climate can be better understood with a little bit of more thermodynamics…”Vani recently joined our group as a PhD in October 2025. She completed her BS-MS dual degree in Earth Sciences from the Indian Institute of Technology Kanpur and will start a PhD project on thermodynamics and maximum power in soil systems. Welcome, Vani!
As the new year is still young, this is good time to reflect on where we are as a group, with our work on thermodynamics and the relevance of entropy for the Earth system and the energy transition, what we have accomplished in the past year, and what to look forward to in the new year, including short courses, conferences etc that we plan to do. It helps to stay optimistic in these difficult times that we currently face. More in this blogpost.
Continue reading “Welcome 2026: Status of our group, our work on thermodynamics, Earth system science, the energy transition, and our plans ahead”
Cool! Ich wurde in die wissenschaftliche Talkshow „Nanotalk“ auf 3sat, einem öffentlich-rechtlichen TV Sender hier in Deutschland, zu Klimawandel und Energiewende eingeladen, zusammen mit Claudia Kemfert und Stefan Thurner. Ausgestrahlt wird sie am Donnerstag Abend um 21:00 auf 3sat, aber jetzt schon als Video online. Wie es dazu kam, wie es war, und eine Sammlung von Links gibt es in diesem Blogpost.
Continue reading “Stromhunger vs. Klimakrise – Das Energiedilemma: Eine Diskussion in Nanotalk auf 3sat – hier mehr Hintergrund und Links zum „Kraftwerk Erde“”
What can we learn from entropy about life on Earth? In this series of videos, I aim to provide the thermodynamic and Earth system background to answer this question. The videos are based on two lectures that I gave in Padova in July 2025. I split the lectures up into an introduction, six questions, and a summary, each in a separate video. This blogpost provides a brief description of the different videos, references for further reading, and the links.
Continue reading “Thermodynamics of the Biosphere: A short series of videos”
How much warmer is the day compared to the night? Or, in other words, how large is the diurnal air temperature range (DTR)? This might seem like a simple question, but the DTR actually varies in surprisingly complex ways across regions and periods. What shapes these variations? What happens to DTR on cloudy days and under clear skies? How does it respond to how wet or dry the land is? And what happens to DTR as the planet warms? We answer these questions in our new study led by Sarosh, published in Geophysical Research Letters. Our goal was to understand the physics behind the DTR using an approach that links the short and long-term variations in DTR to things we can observe and measure, like clouds, sunlight, and surface dryness.
Continue reading “New Article: Explaining observed daily variations and decadal trends in the diurnal air temperature range”
Für ein neues Buch habe ich kürzlich die Daten für Neuzulassungen von Autos angesehen. Wenn man sich die Daten hinsichtlich logistischem Wachstum sich ansieht, ist ganz klar erkennbar: Elektroautos setzen sich weltweit durch, die in Deutschland gesäten Zweifel sind ruinös, und das Verbrenneraus wird noch vor 2035 ganz von selbst eintreten, ganz ohne Politik. Mehr dazu und zum logistischen Wachstum in diesem Blogpost.
Continue reading “Blogpost: Daten zeigen, dass Elektromobilität sich durchsetzt – und wie schädlich Politik in Deutschland sein kann”
Im neuen Video auf Youtube geht es um die Gaia Hypothese, die James Lovelock in den 1970er Jahren formuliert hat. Sie postuliert, dass Leben die planetare Umwelt so verändert und reguliert, dass sie optimal für das Leben ist. Wenn man die Biosphäre als thermodynamisches System betrachtet, welches mit der Erde stark interagiert und dabei ihre Leistung maximiert, ist diese Hypothese gar nicht so abwegig. Mehr Hintergrund in diesem Blogpost.
Continue reading “Neu auf Youtube: Was ist dran an der Gaia Hypothese?”
35 Grad im Sommer – ist das noch normal? Nein, ist es nicht. Es ist der Klimawandel. Im neuen Youtube Video und diesem Blogbeitrag erkläre ich es mit etwas Physik – was Temperaturen im Wesentlichen prägt, wie Variabilität entsteht, und warum Extreme so viel häufiger werden.
Continue reading “Neu auf youtube: Warum extreme Temperaturen so viel häufiger werden”
The new article (original in German) explains the energy transition from a simple but fundamental physical perspective. And something very basic sooner or later leads us to entropy. It helps us understand why electricity-based technologies are much more efficient than those that use combustion and heat as an intermediate step. And why the energy transition is therefore much more of a technical revolution, namely away from heat and towards electricity, with significantly higher efficiency.
Continue reading “New article: Entropy explains why combustion is so inefficient, why electricity is so much better, and how the energy transition is dramatically increasing efficiency”
Der neue Artikel erklärt die Energiewende aus einfacher, aber grundlegend physikalischer Sicht. Und ganz Grundlegendes, das führt uns früher oder später zur Entropie. Mit ihr versteht man, warum strombasierte Technologien wesentlich effizienter sind als solche, die Verbrennung und Wärme als Zwischenschritt nutzen. Und wieso deshalb die Energiewende einer technischen Revolution gleichkommt, nämlich weg von der Wärme und hin zum Strom, mit erheblich höherer Effizienz.
Continue reading “Neuer Artikel: Entropie erklärt, warum Verbrennung so ineffizient ist, es mit Strom soviel besser geht, und wie die Energiewende die Effizienz gewaltig erhöht”
In der gegenwärtigen Energiedebatte wird viel behauptet – Kernenergie soll wieder auferstehen, China setzt ja eh auf Kohle und Deutschland ginge einen Sonderweg. Ein nüchterner Blick auf Stromerzeugung im internationalen Vergleich zeigt klar: Deutschland geht keinen Sonderweg, sondern ist Vorreiter. Mehr dazu in der Terra-X Kolumne mit Harald Lesch und als Youtube Video. Und demnächst als Artikel in Physik in unserer Zeit.
April is here, and geoscientists are once again heading to Vienna. Why? Because Europe’s largest Geoscience Union, EGU, is all set to convene for its General Assembly, EGU25, which take place from 27 April – 2 May 2025. We are thrilled to be there again and share our science. Our group will be contributing to three oral presentations by our PhD student Saurabh and postdocs Tejasvi and Sarosh.
Continue reading “#EGU25: We will be in Vienna to share our latest insights on energetic constraints shaping maximum temperatures, temperature variations with altitude, and potential evaporation estimates.”
Am 23. April 2025, 20:00, Rathaus Schöneberg in Berlin halte ich einen Vortrag im Rahmen der Serie „Wissenschaft Live“ der Wilhelm-Foerster Sternwarte. In diesem Blogpost gibt es Links zu Hintergrundinformationen und Videos.
Continue reading “Öffentlicher Vortrag: Entropie und Leben – eine planetare Perspektive. Mehr Infos im Blogpost”Shengjie recently joined our group as a visiting Postdoc in March. She got a Ph.D. in Environmental Science and Engineering from Zhejiang University, China, working on the evolutionary dynamics of natural (lakes) and human-made (cities) complex systems. Welcome, Shengjie!
In der neuen Terra-X Kolumne geht es um Dunkelflauten – also Wetterlagen, in denen Windenergie und Photovoltaik nicht so viel leisten, wie wir an Strom brauchen. Das ist an sich kein Problem, und es gibt verschiedene Möglichkeiten, diese Differenzen zu decken. In diesem Blogpost gibt’s mehr Hintergrund zur Energiewende, in Form von Artikeln und youtube Videos.
Continue reading “Terra-X Kolumne und auf youtube: Dunkelflauten – sind zwar blöd, aber eigentlich kein Problem. Mehr Infos und Links in diesem Blogpost”
We were back in India, spending a week at the IIT Roorkee to teach a short course on the Second Law in the Earth System Science, giving talks and having discussions at IIT Gandhinagar, IIT Bombay, IISER Pune and IITM. Find out more on what we did and discussed, look at a few photos, and some related papers in this blogpost.
Kernenergie scheint gerade wieder in Mode zu kommen, gerade bei konservativen und populistischen Parteien. Aber ist Kernenergie sinnvoll? Kann sie zur Energieversorgung und Klimaschutz beizutragen? Harald Lesch und ich haben uns dies in einem Artikel in Physik in unserer Zeit genauer angesehen, und kommen zu einer klaren Antwort: Nein, Kernenergie ist zu teuer, zu unflexibel und Versorgungssicherheit bietet sie bei zunehmender Trockenheit in Deutschland auch nicht.
Continue reading “Neuer Artikel und Youtube Video: Kann Kernenergie zur Energiewende beitragen? Oder zum Klimaschutz? Nein, weil sie zu teuer, zu unflexibel, und im Klimawandel keine Versorgungssicherheit bietet.”Soil might not seem like the flashiest player in the Earth system, but make no mistake – beneath its humble surface lies a complex and dynamic world. It is a critical component of our planet, cycling carbon and nutrients, supporting life, and shaping ecosystems. My research group jointly with colleagues from the Soil Biogeochemistry group at the Max Planck Institute for Biogeochemistry, we are embarking on an exciting new journey: applying thermodynamic principles to soils to better understand their processes, dynamics, and limits. And we are looking for a curious mind to join us as a PhD researcher! More infos in this blogpost.
Continue reading “New PhD position: Using Energy and Optimality to Unearth the Secrets of Soil”Rainfall events are expected to intensify everywhere because warmer air can hold more moisture. However, testing this relationship with observations across warmer regions and periods sometimes seem to contradict this expectation, showing negative or inconsistent trends. Our new study published in Nature Communications and led by Sarosh shows that it is mainly the cooling effect of clouds associated with rainfall that causes these discrepancies. By accounting for this effect, we resolve the apparent mismatch between observations and theory, providing evidence of increases in extreme rainfall with warmer temperatures. More information in this blogpost and in the paper.
Continue reading “New Paper: Clouds obscure the link between extreme rainfall and rising temperatures”
Wind turbines generate electricity by removing kinetic energy from the winds – after all, that is what they are designed to do. The more wind turbines are deployed within a region, the more the wind speeds must be reduced, thereby impacting the wind resource potential of the region. In our new paper we tested our KEBA approach with much more complex numerical weather simulations and found that accounting for the removal of kinetic energy captures the dominant effect, but one also needs to distinguish between daytime and nighttime conditions. This removal effect lowers the resource potential of Kansas by more than 60%, but still yields substantial amounts of electricity – more than Germany currently consumes. More infos in the blogpost and in the paper.
Continue reading “New paper: Towards better, simpler, and physically-based estimates of regional wind resource potentials – Testing our KEBA approach with simulations for Kansas”Im neuen Video zum Kraftwerk Erde geht es um den atmosphärischen Treibhauseffekt – speziell, um die Rolle des atmosphärischen Fensters. Über die Faktoren, die die Größe und Durchlässigkeit dieses Fensters beeinflussen, kann man recht einfach, aber physikalisch, direkt Muster der globalen Klimaerwärmung erklären. Im Blogbeitrag gibt es die Referenzen dazu.
About 15 years ago I published a paper on “Life, hierarchy, and the thermodynamic machinery of planet Earth”. This paper was quite influential for me as it clarified many things about how the second law of thermodynamics applies to the Earth system. It led to quite a few applications of thermodynamic limits in climate science and renewable energy that worked really well and that I found insightful because it allows us to do climate science in a simple yet physically-based way. The follow-up paper just published provides a summary of this approach and explores potential, more concrete applications of how the biosphere optimizes its form and functioning, and on life on Earth and beyond in general.
Continue reading “New Paper: The Second Law of Thermodynamics, Life and Earth‘s Planetary Machinery Revisited”With global warming, heatwaves are becoming more frequent, intense, and prolonged, impacting ecosystems, food production, infrastructure, and human health. In our recent study published in Communications Earth & Environment led by Yinglin Tian, we show that heatwaves do not all operate in the same way. They arise from diverse processes that are reflected in characteristic differences in surface energy balance partitioning, each with distinct impacts on ecosystems and different trends under global warming.
Continue reading “New Paper: What make heatwaves different and how do their impacts on ecosystems vary?”
We just finished our summer vacation, but that‘s no break from feeling the impacts of global warming. This year we crossed the Austrian Alps and the Appenin mountains in central Italy with our bikes – but where were the ice-covered peaks and why was Italy so hot? Some thoughts on the basic physics involved and why climate change may already be more severe than what some models anticipate.
Continue reading “Notes from vacation: Thoughts on why climate change impacts in the Alps and Italy are already much more severe than what a 1.5 degree target suggests”Es gibt sie ja immer noch, Klimawandelleugner und Akteure, die aus Eigeninteresse Falschinformationen und Zweifel zum Klimawandel verbreiten. Als Physiker kann ich da nur fassungslos mit dem Kopf schütteln, weil Beobachtungen und Physik den Klimawandel zweifelsfrei bestätigen. Es gibt aber auch Mitmenschen, die den Klimawandel nicht wahrnehmen, und das ist ja was ganz Menschliches. Wer erinnert sich schon an das Klima vor dreizig Jahren? Der Klimawandel hat Deutschland schon deutlich zugeschlagen, und man kann ihn physikalisch nachvollziehen – dazu dieser Blogpost mit Analysen, die ich kürzlich mit Messungen an Wetterstationen in Deutschland durchgeführt habe und weiterführende Links. Und sie zeigen, dass der Klimawandel schon krasser gekommen ist als erwartet.
Continue reading “Warum der Klimawandel in Deutschland stärker als erwartet ausfällt. Und ganz klar sichtbar ist, wenn man nachsieht. “The interesting parts of the Earth system are those that perform work, show dynamics, build and maintain structures, deplete gradients, dissipate and produce entropy – in short, dissipative systems. These dissipative systems operate far from the boring state of thermodynamic equilibrium and show interesting behavior, such as well formed structures and power-law scaling. A good topic for a short intro course, because it is one of the lesser known aspects of Earth systems, and a good occasion to meet and talk about. That‘s what we‘ll do in September at the University of Florence in Italy. And to make the topic not quite about everything on Earth, we will focus on hydrogeosystems.
Continue reading “Workshop on dissipative Earth systems in Firenze in September 2024 … or how the Second Law connects power and dissipation with distributions, structures and information in Earth systems.”It only takes a little basic physics to describe the essence of the hydrological cycle. This allows us to reproduce climatological variations and the changes with global climate change very well. It is described in a recently published article (english translation on arXiv) and is explained in two YouTube videos on basics and droughts and on heavy rainfall (in German, but you can use subtitles).
Continue reading “New article and YouTube videos: How energy and thermodynamics shape the hydrological cycle. And how this can explain more drought and heavy rain with global climate change (translated blogpost)”Es braucht nur etwas grundlegende Physik, um das Wesentliche des Wasserkreislaufs zu beschreiben. Damit können wir klimatologische Variationen und die Änderungen mit dem globalen Klimawandel sehr gut wiedergeben. Dies ist im gerade veröffentlichten Aufsatz beschrieben und in diesem Youtube Video erklärt.
Continue reading “Neuer Artikel und Youtube Video: Wie Energie und Thermodynamik den Wasserkreislauf formt. Und wie dies mehr Trockenheit und Starkregen im globalen Klimawandel erklären kann.”
Combustion engines, gas boilers, coal-fired power stations: all these technologies are based on combustion. Physics clearly shows that this is not efficient. We have known for a long time how to do it better. Here the translated (and illustrated) version of my Terra-X blogpost.
Continue reading “Combustion technologies are dead – translated version of my Terra-X blogpost (and yes, it’s because of the entropy)”Saurabh recently joined our group as a PhD student in April this year. He completed his BS-MS dual degree in Earth Sciences from the Indian Institute of Technology (IIT) Kanpur, India. Welcome, Saurabh!
Continue reading “Introducing new PhD student: Meet Saurabh Shukla”In der zweiten Folge der Serie zum Kraftwerk Erde geht es um die Temperaturen der Erde. Thermodynamisch gesehen erzeugen räumliche und zeitliche Unterschiede in der Erwärmung durch Sonnenlicht und der Kühlung durch Abstrahlung ins Weltall Temperaturunterschiede, also Zustände von thermodynamischen Nichtgleichgewicht. Dieses wird vom „Kraftwerk Atmosphäre“ genutzt, um Arbeit zu leisten, Luft zu bewegen, Wärme zu verteilen, und Nichtgleichgewicht abzubauen. Mit Datensätzen vom Strahlungsantrieb und der maximalen Leistung dieses Kraftwerks lässt sich dann wunderbar nachvollziehen, warum Wüsten wärmer sind als Regenwälder, warum sich im globalen Klimawandel Land stärker erwärmt als der Ozean, und warum sich Deutschland in den letzten Dekaden so stark erwärmt hat.
Continue reading “Neu auf Youtube: Wie der Ansatz vom „Kraftwerk Erde“ einfache, aber physikalisch-basierte Klimaforschung und das Nachrechnen von Temperaturmustern und Trends ermöglicht”
On 22nd February 2024, I successfully defended my PhD thesis on “Interactions between hydrological cycle and land-surface temperatures: insights from a thermodynamic systems perspective”. With this, I have finished my joint PhD program at Max Planck Institute for Biogeochemistry and Karlsruhe Institute of technology (KIT). This blog post briefly summarizes my PhD journey from how I chose this topic, the work I did in my PhD, and the implications of my work.
Continue reading “Sarosh finishes his PhD on “Interactions between hydrological cycle and land-surface temperatures: insights from a thermodynamic systems perspective””
It’s April again, the month when Europe’s largest geoscience union, EGU, convenes for its General Assembly in Vienna, Austria. This year, EGU-24 is scheduled to take place from 14 – 19 April 2024, and we are thrilled to be there and share our science. Our group will be contributing to several presentations, including those by Tejasvi, Sarosh, Axel, Pinhsin and Yinglin.
Continue reading “#EGU24: We will be in Vienna to share our updates on thermodynamics, hydrologic sensitivities, biodiversity-climate interactions, temperature extremes and wind energy impacts.”Entropie und der zweite Hauptsatz der Thermodynamik setzt die Grundlage dafür, wie das Erdsystem aus Sonnenlicht Arbeit erzeugen kann. Die Grundlagen dafür werden in der ersten Folge einer Serie von Videos beschrieben, die das „Kraftwerk Erde“ näher behandelt und die in den nächsten Monaten auf dem Youtube Kanal Urknall, Weltall, und das Leben erscheint.
Continue reading “Neu auf Youtube: Warum ist Entropie für das Erdsystem so wichtig? Weil es die Leistung begrenzt und damit die Dynamik des Erdsystems.”On 23rd March 2024, Sarosh gave an invited talk at the International water conference on sustainable development goals (IWCSDG-2024) held at NIT Bhopal, India. His presentation focused on using thermodynamic limits as an additional constraint to model the hydrological cycle and estimate the hydrological fluxes.
Our last stop is Kashmir, where we hold a weeklong workshop on thermodynamics and optimality in climate, water cycle, ecosystems, renewable energy and sustainability. We have intense and stimulating interactions, hands-on sessions organized by Sarosh and Tejasvi, and an excursion into the mountains.
Continue reading “Touring India 2024 – Stop 4: Short course and workshop on thermodynamics and optimality of Earth systems at the Islamic University of Science and Technology near Srinagar, Kashmir”
Our next stop is at the IIT Kanpur, 400 km east of Delhi at the banks of the Ganges river. Time passes quickly. We spend time preparing lectures, meeting Saurabh – our future new PhD student – and participated in a workshop on sustainable cities. There, we had enlightening discussions on fractals, power laws, and how these relate to thermodynamics and can be applied to cities.
Continue reading “Touring India 2024 – Stop 3: Workshop and inspiring discussions on sustainable cities, thermodynamics and fractals at IIT Kanpur”
Our next stop is Aligarh Muslim University – the home and Alma Mater of Sarosh, who just completed his PhD in my group. We visit the campus, talk thermodynamics, meet faculty and Sarosh’s family.
Continue reading “Touring India 2024 – Stop 2: Visiting Aligarh Muslim University in Aligarh, about 130 km east of Delhi”We are back in India again, travelling to Delhi, Aligarh, Kanpur and Kashmir. We will meet good friends and colleagues, interact with students, to talk thermodynamics and Earth system science in seminars, at nice places worth seeing, and in a week-long short course in Kashmir. And we’ll enjoy the company and the good food.
Continue reading “Touring India 2024 to talk about thermodynamics, climate, renewable energy and sustainability at various places. Stop 1: Delhi”Tejasvi recently joined our group as a Postdoc in October last year. He got a Ph.D. in civil engineering from the Indian Institute of Technology (IIT) Bombay, Mumbai, India, working on land surface-atmosphere dynamics and information theory. Welcome, Tejasvi!
Continue reading “Introducing New Postdoc: Meet Tejasvi Ashish Chauhan”Ich bekomme ab und zu Anfragen, ob Photovoltaik nicht auch das Klima aufheizt. Solarpaneele sind ja schliesslich dunkel und heizen sich in der Sonne ordentlich auf. Ein guter Grund, mal einen Blick auf die Energiebilanz und Ausbauziele zu werfen, um zu verstehen, dass die möglichen Auswirkungen auf Temperatur gering sein werden.
Downwelling longwave radiation dominantly heats the Earth’s surface across the globe and shows systematic variations in space and time. In our new paper, we showed that these variations are predominantly shaped by changes in the heat accumulation within the lower atmosphere, while changes in cloud-cover and water-vapor remain a secondary contributor.
Continue reading “New paper: Explaining the climatological variations in downwelling longwave radiation across space and time”Die Erde arbeitet wie ein Kraftwerk und folgt dabei den Hauptsätzen der Thermodynamik. Dabei wandelt sie Sonnenenergie in andere Energiearten um und prägt so die Dynamik des Erdsystem. Allein durch diesen grundlegenden physikalischen Ansatz kann man schon erstaunlich viel vom Erdsystem verstehen, von den Hauptfaktoren, die Temperatur und Wasserkreislauf bestimmen, die Vegetation begrenzen bis zu den Auswirkungen des Klimawandels und den Grenzen erneuerbaren Energien.
Das Video vom Vortrag vom 07. November 2023 vor den Freunden des Planetariums Göttingen ist jetzt auf youtube zu sehen. Auf dem Blog sind die Folien sowie Verweise zu Hintergrundliteratur.
#AGU23 is around the corner!Pinhsin will be there and present her poster on “Plant trait diversity stabilizes climate in a wet and cool state via maximizing terrestrial water recycling” on Thursday, December 14th, 8:30 AM – 12:50 PM PST, in the session “GC41M: The Global Water Cycle: Coupling and Exchanges Between the Ocean, Land, Cryosphere, and Atmosphere I Poster” at MC, Poster Hall A-C – South.
Continue reading “#AGU23: Assessing the Impact of Plant Diversity on Terrestrial Climate: Join us at AGU’s fall meeting to explore our poster!”
Photovoltaik ist die Energie der Zukunft – wie ich es kürzlich auf dem Terra-X Blog beschrieben habe. Aber warum? Das kann man recht einfach aus grundlegender Physik erschliessen. Genauer gesagt, es geht um Entropie, und wie sich aus Sonnenlicht am effizientesten Energie gewinnen lässt. Und daraus zeigt sich, dass die Photovoltaik nahezu unschlagbar ist in ihrer Effizienz. Hier gibt‘s mehr Hintergrundinfos und Links zu Literatur.
Entropy has intrigued me for a long time – it usually comes up at the very end of asking “why” questions. It is such a fundamental concept in physics, but then – why does nobody talk about it in Earth system science? My review paper just published in Earth System Dynamics explains why entropy is so essential to understand the dynamics of the Earth system: because it limits how much work can be done, and work is at the very core of what we call dynamics.
Continue reading “New paper: Working at the limit – how entropy, work and limits shape Earth system functioning. Here is a simple, but long summary of the key points.”Interested in getting a PhD on evaporation, water stress and droughts with observations and simple, physical theory? We have a new opening within the most recent call of the International Max-Planck Research School on global BioGeochemical Cycles (IMPRS-gBGC). Apply through the website by 21 August 2023.
Continue reading “New #PhDposition: Using observations and novel theory to infer water stress and droughts on land using an #EarthSystemScience approach”Surface temperatures over land are affected by the vertical turbulent exchange of heat and moisture from the surface to the atmosphere. While these processes are inherently complex, we show in our new article that by accounting for thermodynamic limits, the observed temperature patterns follow relatively simple and predictable rules.
Continue reading “New Paper: Revealing the power of motion in shaping land-surface temperatures”
Sustainability is a popular topic these days, but what does it actually mean? What does it take to sustain life on Earth in the presence of increased human pressures, and what does it imply for a sustainable future? In a recent paper I combined thermodynamics with an Earth system approach to look at these questions.
Continue reading “New paper: Sustaining the biosphere in the Anthropocene – not as simple as it may sound”
The expansion of wind energy plays a central role in the energy transition. But how much can actually be used, and how strongly is the atmosphere affected? I am currently receiving a number of inquiries about this, e.g., based on a video which uses earlier work (Kleidon 2019, Kleidon 2021). Conveniently, a new paper has just been published in Physik in unserer Zeit, which answers exactly these questions.
Continue reading “New paper: How much wind energy is there in Germany? We estimate the efficiency losses and impacts of wind energy expansion at 200 GW in Germany using a simple, physical approach.”
Im Rahmen der Energiewende spielt der Ausbau der Windenergie eine zentrale Rolle. Aber wieviel lässt sich eigentlich nutzen, und wie stark wird die Atmosphäre beeinflusst? Dazu erhalte ich gerade eine ganze Reihe von Anfragen, auch aufgrund eines Videos, welches sich auf frühere Arbeiten von mir (Kleidon 2019; Kleidon 2021) bezieht. Praktischerweise ist dazu gerade ein neuer Artikel von mir in Physik in unserer Zeit erschienen, der genau diese Fragen beantwortet.
Just like in pre-Corona times, April is the month in which Europe’s largest geosciences union convenes for its General Assembly in Vienna, Austria. We are excited to be there, present our latest research, and look forward to seeing and talking to you there!
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.
Continue reading “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.”
“The whole is more than the sum of its parts” – this has been said by smart people throughout human history, from Aristotle to Gibbs. But how does it apply to the vastly complex Earth system? In the book chapter just published I describe how this focus on the whole combined with a thermodynamic formulation of the Earth system including life helps us to understand that the whole is more, and simpler, than the sum of its parts. This is because complex, natural systems appear to work at their thermodynamic limit. The emergent functioning may then very well share characteristics similar to those postulated by the controversial Gaia hypothesis of James Lovelock, which states that life regulates the Earth for its own benefit.
Continue reading “New Book Chapter: Understanding the Earth as a Whole System: From the Gaia Hypothesis to Thermodynamic Optimality and Human Societies”
Winter is coming, snow is falling, and here in Jena we will need gas to heat our homes. Gas prices are at their all-time high, so how much heat do I need and how can I reduce it? I describe a simple, physical way to estimate how much energy I should need to heat our home, and how this can help to find out how effective measures are to reduce energy consumption.
Continue reading “New Blogpost: How much energy will I consume to keep our home warm this winter? A simple estimate, utilizing climate data, gas meter readings, and past gas bills. And yes, the second law comes into play as well.”
Offshore wind energy is rapidly growing, but what happens when more and more wind turbines deplete the regional wind energy resource?
Continue reading “New Paper: Estimating #offshore #windpower in the German bight. It describes the depletion effects of the #windenergy resource and its implications for the 70 GW target in an accessible way, based on our Agora Energiewende study. https://doi.org/10.1002/piuz.202201654 https://export.arxiv.org/pdf/2301.01043”It is that time of the year again and the AGU Fall Meeting is all set to take place in the hybrid format. This year two members of our lab Sarosh Alam Ghausi and Yinglin Tian will be presenting their research in person at the conference.
Continue reading “#AGU22: We will be in Chicago next week to present our updates about thermodynamic and energetic controls on land-atmosphere exchange and Arctic sea ice loss events”Rainfall events are expected to become heavier as the hydrologic cycle intensifies with global warming. To determine this strengthening, many studies use observed precipitation events and test how these change with observed temperatures. These so-called scaling rates differ from what is expected from theory, showing a decline above temperatures of around 23° – 25°C. This breakdown in scaling makes it difficult to interpret the precipitation response to global warming and its cause further remains unclear. It also raises the question of whether a high-temperature threshold limits the increase in the intensity of precipitation events with temperature. We resolve this in our latest paper by showing that the break in scaling primarily occurs due to radiative effect of clouds on surface temperatures that leads to a covariation between the two variables.
Continue reading “Can we infer rainfall sensitivity to global warming using observations of precipitation and temperature? Not quite, until you correct for the cooling effects of clouds.”How does the second law of thermodynamics apply to the Earth system and why is it so important? As it turns out, it dominantly shapes natural Earth system functioning, from the climate system to hydrologic cycling, the biosphere, and renewable energy resources, yielding simple, emergent functioning as a consequence of systems operating at their thermodynamic limits. This short course provides the basics to understand why entropy is so important and how it shapes Earth system functioning.
Continue reading “Short course on „Thermodynamics and Optimality in the Earth system“ – live in Florence and accessible online. If you ever wanted to know why the second law is so important, come and join!”
Over land, there is a marked variation in surface and air temperature during day and night, with the amplitude described by the diurnal temperature range. What are the main factors that determine its magnitude across regions and how much is it shaped by evaporation? This is what Annu Panwar looked at in her last part of her PhD using FluxNet observations and the ERA 5 reanalysis products, with the results just published online in the Journal of Climate. What this analysis shows is that energy balances go a long way to explain the main influences and that evaporation does not have quite such a strong effect as one may think.
Continue reading “How much does evaporation affect temperature variations during the day? That’s what we looked at in a paper just published online in the Journal of Climate. @annuPanwar_sci @ametsoc @MPI_BGC”Corona is still around, also in Vienna, but the EGU General Assembly will nevertheless happen again, in a hybrid form. We are thrilled to be there physically, giving our 6 minute short talks on our work, and look forward to seeing and talking to you there!
Thermodynamics, entropy and life — does this sound intriguing but also confusing to you? As part of the virtual Spring School on Physics and Mathematics applied to Ecology, organized by Oliver Lopez Corona, I give a lecture where I will cover how thermodynamics applies to the biosphere and the planetary environment, and how it connects to concepts such as the Gaia hypothesis or planetary boundaries. Hopefully, after the lecture, it is clearer to you what entropy is, how it applies to the Earth system, its biosphere, and their interactions. And why it is so important! If you are interested to learn more, this blogpost provides some links to literature mentioned in the lecture.
Continue reading ““Thermodynamics and Optimality of the Biosphere” – online lecture, today, Friday, March 25, at 17:00 Jena time (CET) or 10:00 in Mexico. Interested? You can join too, if you like, here’s the link and background material.”The position is in my research group, which focuses on how the Earth functions as a whole system, the role of life within it, and what a sustainable human future might look like. We take a unique Earth system approach that focuses on thermodynamics, energy conversions, and limits/optimality such as maximum power.
We are seeking a motivated and interested person to help us further develop this approach, evaluate it using observational data, and/or compare it to climate model results. More details are provided in the formal job announcement, which you can find here. More background information in this post.
Continue reading “Interested in how the Earth system works? I have a #PostDoc opening available in my group, applying thermodynamics, max. power, and optimality to Earth system science. @MPI_BGC”
Evaporation cools, right? What may sound so obvious was the topic of Annu’s PhD thesis: to look into observations and find the effects of evaporation in how surface and near-surface air temperatures vary throughout the day. The results are not quite as obvious, and we learned a lot. Here is a brief summary of her thesis, with its contents spread over three papers. Very nice work!
Continue reading “Last week our group member @annuPanwar_sci successfully defended her PhD thesis on diurnal temperature variations and how they are affected by evaporation and vegetation. Very well done, and congratulations, Annu! @mpibgc”
In Germany, the construction of Tesla’s Gigafactory near Berlin draws its attention, including its substantial need for freshwater. Despite its many lakes, the area around Berlin is among the driest in Germany. The atmosphere contains water vapor, and it seems like a tempting source for freshwater, just sitting there to be harvested by some form of technology. This is what a company claims to do (and quite a few others elsewhere as well). But can this promise hold up?
Continue reading “Can we solve the freshwater problem by taking moisture out of the atmosphere with dehumidifiers? When we look at how the hydrologic cycle does its work, we get a straight and clear answer: no, we don’t solve the problem!”
Die Erde arbeitet wie ein Kraftwerk, indem sie Sonnenenergie in andere Formen umwandelt, die die Winde der Atmosphäre, den Wasserkreislauf, und auch das Leben und die Menschheit auf der Erde erhalten. Diese Umwandlungen folgen den Gesetzen der Thermodynamik, die sowohl die Richtung als auch die Grenzen setzt. Aber Erdsystemprozesse beeinflussen sich auch gegenseitig, sodass man einen Blick auf das Gesamtsystem braucht. In diesem Vortrag zeige ich, dass man allein durch diesen grundlegenden physikalischen Ansatz schon erstaunlich viel vom Erdsystem verstehen kann – über die fundamentalen Rolle von Energie und Entropie, wie Leben den Planeten verändert, aber auch zu angewandten Themen wie dem Klimawandel und warum die Photovoltaik die Technologie ist, die bei weitem den größten Beitrag zur Energiewende liefern wird.
Continue reading ““Kraftwerk Erde: Wie der belebte Planet Energie umwandelt” – Vortrag bei #FasziAstroOnline, heute Abend, 13.01.2022, 19 Uhr, live auf youtube. Mehr Infos im Blog. @MPI_BGC @HdAstro”Im Rahmen der Ringvorlesung “Lectures for Future”, zusammen veranstaltet von der Hochschule München und der LMU, hält Axel Kleidon einen Vortrag zu unserem thermodynamischen Erdsystemansatz und was man daraus für Nachhaltigkeit lernen kann. Der Vortrag ist öffentlich und kann über diesen Zoom Link gesehen werden.
Continue reading ““Was leistet die Erde und was trägt die Menschheit dazu bei? Nachhaltigkeit aus thermodynamischer Sicht.” zoom-Vortrag, öffentlich, Montag, 13.12.2021, 18:00, tinyurl.com/HM-ForFuture”Corona has not yet gone away, but the AGU Fall Meeting nevertheless takes place, in a hybrid format. Annu Panwar will be physically there, giving an invited talk on her PhD thesis on diurnal temperature variations (see, e.g., her paper in HESS) and a poster, while Sarosh Alam Ghausi will be giving his poster on precipitation scaling virtually.
Continue reading “At #AGU21, we present updates on understanding diurnal temperature variations on land and on deriving precipitation sensitivities from observations using “clear-sky” temperatures and maximum power”Global warming, biodiversity loss, freshwater shortages, food crisis — there are many reasons to think that the planetary future looks rather grim for human societies. Is there any hope that things can turn out well? It is quite hard to remain optimistic, yet when looking at it from basic physics one can find a way forward. In this book chapter that has just been published online I looked at the issue of sustainability and the role of technology using our thermodynamic Earth system approach.
Continue reading “Empowering the Earth system with technology: Using thermodynamics to illustrate the possibility of sustained future growth of human societies”Wieviel erneuerbare Energie gibt es eigentlich? Reicht sie für die Energiewende in Deutschland? Die Antworten liefern einfache, physikalisch-basierte Abschätzungen, bei der das Erdsystem im Mittelpunkt steht sowie die Umwandlungen von der Energie im Sonnenlicht in andere Formen. Und dabei steht etwas Physik, genauer gesagt, die Thermodynamik im Mittelpunkt. Das Ergebnis ist nicht ganz so, wie man es vielleicht erwarten würde. Nämlich, dass es zwar jede Menge erneuerbare Energie gibt, aber auch, dass die Nutzung der Solarenergie mit großem Abstand auf Platz 1 liegt, und nicht die Windenergie. Selbst im nicht ganz so sonnigen, aber oft windigen Deutschland.
Continue reading ““Erneuerbare Energien – einfach nachgerechnet” – unser Beitrag zum MINT Festival der @UniJena am Donnerstag. Hier gibt’s weitere Infos und Links. #moMINTmal21 @MPI_BGC”
With summer coming to a close, we are back to present new insights from ongoing research in extreme precipitation events, offshore wind energy and thermodynamics at the European Meteorological Society Annual Meeting 2021. The event, which will be held online next week (6 – 10 September 2021), focuses on weather and climate research and services for the achievement of the UN Sustainable Development Goals. Read on to find out more details about when and what each of us will be presenting.
Continue reading “#vEMS21: Our updates on using #thermodynamics for land-atmosphere interactions, the precipitation response to #globalwarming, and the #windenergy potential in the German bight”
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.
Continue reading “#goldschmidt2021 We contribute our work on dissipative dynamics and frequency distributions in river geochemistry and an update on the thermodynamics of planetary evolution.”
Denmark plans to expand offshore wind energy, and to do so, wants to create an artificial island in the North sea. This plan is based on a cost-benefit analysis, which is based on an estimate of how much electricity generation can be expected from wind turbines in that region. Such wind resource estimates use highly resolved wind fields, turbine characteristics as well as their spatial arrangement, but they typically neglect the atmospheric response to the turbines. Each turbine removes kinetic energy from the atmosphere to generate its electricity, so more turbines remove more energy from the atmosphere, leaving a greater impact behind. What this means is that such estimates typically turn out to be too high (see e.g., here), with a greater bias with greater installed capacity, as we have shown for German offshore scenarios, or in a new study just published. So when a colleague asked me about my opinion, I thought this is a good occasion to use our KEBA approach, which takes the atmospheric response into account, and redo the estimate.
Continue reading “The Danish energy island in the North sea: By how much could the atmospheric response to many wind turbines lower the expected yields? Using KEBA to derive a simple, physical answer.”
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”
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.”
From time to time I get e-mails asking me about what our work on wind energy limits implies for the German transition to sustainable energy. With the substantial expansion of wind power in Germany over the last decade, are we getting close to the limits of wind energy that the atmosphere can provide? I looked at the latest ERA-5 weather data product to get answers, and instead of just e-mailing answers, I wrote this blogpost as well to share the insights.
Continue reading “How close is German wind energy use to its limit? A quick check using climate data shows that it currently represents a few percent of the maximum, but may get quite close to its limits by 2050.”Corona has impeded everything in 2020 including researchers’ involvement in scientific conferences. However, innovation and the internet made it possible to contribute to large and much anticipated conferences like the AGU Fall Meeting ‘20. Thus, 2 of our PhD researchers, Annu Panwar and Jonathan Minz, presented their scientific results, keeping the spirit of science communication alive, despite tough times.
Continue reading “AGU Fall Meeting 2020: A brief summary of our contributions and takeways”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.”
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.”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”
Photosynthesis 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?
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.”
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.”
Winds over the ocean typically have higher wind speeds, resulting in high efficiencies of wind turbines and making this an attractive environment for generating a lot of renewable energy. But how efficient are turbines going to be when offshore wind farms become larger and larger? Continue reading “More offshore wind energy is likely to reduce turbine efficiencies, but still a lot of renewable energy can be generated. This is what a new @AgoraEW study shows to which we contributed.”
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.”
In meteorology, air temperature measurements are typically taken 2m above the surface. It is a routine measurement at weather stations, and this temperature is the basis for analyzing trends, such as global warming. The temperature of the surface is not so often measured, but it can be inferred by satellites from how much radiation is being emitted by the surface. Being only 2m apart, one may think that the temperatures basically reflect more or less the same, given their close proximity. We actually found out that this is not the case: surface temperature responds much more strongly to a lack of water than air temperature. This finding was just published in our article in the journal Geophysical Research Letters. Continue reading “If you think surface and air temperature are basically the same thing, think again. Or read our new paper.”
I thought it might be a good idea to meet with wind energy critics to hear what they have to say. But my experience told me otherwise. Perhaps I should have been warned. They are associated with a German organization called „Vernunftkraft“, which has „sensible“ in its name. How presumptuous! It should have been a red warning flag for me. Continue reading “Making sense of German wind energy”
Why do I start writing a blog? Well, I see a few reasons: Continue reading “Starting a blog”
Earthsystem.org 