







































Ecology, Economy and Society–the INSEE Journal 6(1): 53-80, January 2023 

 

RESEARCH PAPER 

Sustaining the Terrestrial Biosphere in the Anthropo-
cene: A Thermodynamic Earth System Perspective 

Axel Kleidon 

Abstract: Many aspects of anthropogenic global change, such as shifts in land cov-
er, the loss of biodiversity, and the intensification of agricultural production, threat-
en the natural biosphere. The implications of these specific aspects of environmen-
tal change are not immediately obvious; therefore, it is hard to obtain a bigger pic-
ture of what these changes imply and distinguish the beneficial from the detri-
mental, where human impact is concerned. In this paper, I describe a holistic ap-
proach that allows us to obtain such a bigger picture and use it to understand how 
the terrestrial biosphere can be sustained in the presence of increased human activi-
ty. This approach places particular emphasis on the free energy generated by pho-
tosynthesis—energy that is required to sustain both the dissipative metabolic activi-
ty of ecosystems and human activities (with the generation rate being restricted by 
the physical constraints of the environment). Thus, one can then identify two types 
of human influence on the biosphere and their resulting consequences: the detri-
mental effects caused by enhanced human consumption of this free energy and the 
beneficial effects that allow for more photosynthetic activity and, therefore, more 
dissipative activity within the biosphere. I use examples from the terrestrial bio-
sphere to illustrate this view and global datasets to indicate how this can be quanti-
fied. Thereafter, I discuss how certain aspects of modern technology can enhance 
free energy generation within the terrestrial biosphere, which can, in turn, safeguard 
its sustenance even as human activity increasingly shapes the functioning of the 

Earth system. 

Keywords: Global change, Sustainability, Maximum power, Exergy, Planetary 
boundaries 

1. SUSTAINABLE ENERGY AS THE CORE PROBLEM OF THE 
ANTHROPOCENE 

 
 Max-Planck-Institut für Biogeochemie, Hans-Knöll-Str. 10, 07745 Jena, Germany, aklei-
don@bgc-jena.mpg.de  

Copyright © Kleidon 2023. Released under Creative Commons Attribution © 

NonCommercial 4.0 International licence (CC BY-NC 4.0) by the author.  

Published by Indian Society for Ecological Economics (INSEE), c/o Institute of  Economic 
Growth, University Enclave, North Campus, Delhi 110007.  

ISSN: 2581–6152 (print); 2581–6101 (web).  

DOI: https://doi.org/10.37773/ees.v6i1.915  

mailto:akleidon@bgc-jena.mpg.de
mailto:akleidon@bgc-jena.mpg.de
https://doi.org/10.37773/ees.v6i1.915


Ecology, Economy and Society–the INSEE Journal [54] 

 

 

Energy is at the core of many aspects of global change we currently face, 
including those that challenge the functioning of the biosphere. What I aim 
to show here is that a focus on energy and how it is variously transformed 
within the Earth system helps us to get a clearer, bigger picture of how cur-
rent human activity inevitably results in a diminished biosphere. However, 
using certain forms of technology, we can make informed choices that will 
contribute to supporting and sustaining the natural biosphere as human 
activities increasingly shape planetary functioning. 

Let us first look at how current global changes are related to energy with 
the help of a few examples. An obvious place to start is with global climate 
change or global warming. The increased consumption of fossil fuels direct-
ly relates to the increased energy needs that human societies have to fuel 
their socioeconomic activities. The inevitable consequence of this is in-
creased greenhouse gas concentrations within the atmosphere, which con-
sequently causes the climate to change. Thus, increased human energy con-
sumption has a direct connection to global warming. 

The link is not as obvious when we look at tropical deforestation as another 
example. Tropical deforestation is mainly caused by the conversion of natu-
ral forests into pastures and croplands. This conversion aims at producing 
more food, which relates to calories that human metabolism needs for sus-
tenance. Thus, an expansion of agricultural area relates to an increase in 
food production, which is equivalent to the energy stored in chemical com-
pounds in food. Thus, tropical deforestation can also be linked directly to 
increased human energy needs. 

The loss of biodiversity is the last example I would like to examine. While 
many factors are considered detrimental to biodiversity (IPBES 2019), such 
as land cover shifts, habitat destruction, and intensified agriculture, energy is 
a central factor at play. Each organism needs chemical energy to sustain its 
metabolism, and this energy comes from photosynthesis. Several hypothe-
ses explain biodiversity patterns in terms of energy (for example, reviews by 
Currie et al. 2004 and Clarke and Gaston 2006). In essence, these hypothe-
ses start by recognizing that tropical regions have more energy available due 
to their higher productivity. Sunlight and water are abundantly available 
throughout the year, resulting in high sustained rates of photosynthesis by 
terrestrial ecosystems. This higher rate of photosynthesis generates more 
free energy, allowing tropical ecosystems to sustain the metabolisms of 
more organisms, and, thus, higher diversity levels, which is reflected, for 
instance, in greater species richness. Therefore, when humans convert and 
use land more intensively for food production, there is less energy available 
for the metabolic activities of the natural biosphere. Hence, the loss of bio-



[55] Kleidon 

 

 

diversity with increased and intensified land use also seems to be a direct 
consequence of greater human energy demands.  

These examples illustrate a general dilemma resulting from human activity. 
As human activity increasingly appropriates energy from the biosphere, less 
energy remains for the sustenance of the natural biosphere (Figure 1). A key 
element of this dilemma is that the biosphere’s productivity has natural lim-
its set by the environment. This, in turn, sets limits to the sustainable 
growth of human societies, as described in detail in the seminal work The 
Limits to Growth by Meadows et al. (1972). When human societies grow and 
develop, and increasingly appropriate their energy from the biosphere, this 
inevitably results in a deteriorated energy supply for the natural biosphere, 
thus posing a serious threat.  

I propose a general approach to understand how this deterioration of the 
natural biosphere can be avoided by decoupling an increase in energy con-
sumption by human societies from a proportional decrease for the rest of 
the biosphere. To do so, we need to evaluate how technology can be used 
to enhance photosynthesis beyond its natural limits, thus ensuring that a 
larger amount of energy would be available for use by human societies 
without compromising on the share available to the natural biosphere 
(marked in Figure 1 as ‘Feedback’). Such technologies have been used in the 
past. Irrigation-based agricultural techniques (using river water or manmade 
reservoirs) have been in use for thousands of years to enhance agricultural 
productivity. The river Nile in Egypt is a good example of this. Diversion 
makes water available for terrestrial productivity that cannot be achieved by 
natural means, that is, without the technology associated with building dams 
and irrigation channels. In the future, technologies may be used to accom-
plish this task with a much greater impact, particularly, by using methods 
related to seawater desalination and photovoltaics. Seawater desalination by 
membranes is a more efficient means of desalination than the natural hy-
drologic cycle of evaporation and subsequent precipitation. Similarly, pho-
tovoltaics is much more efficient than natural photosynthesis for energy 
generation. These technologies can decouple the energy and water needs of 
human societies from natural systems and simultaneously provide an im-
mense boost to energy availability for human societies. This would then 
allow for a large amount of naturally generated energy to be available to 
sustain the natural biosphere, potentially resulting in positive feedback (as 
indicated by the dotted line in Figure 1). 



Ecology, Economy and Society–the INSEE Journal [56] 

 

 

Figure 1: A Basic Dilemma Emerges from How the Energy Generated by Photo-
synthesis Is Being Used to Sustain Nature or Human Societies 

 

Source: Author 

To substantiate this approach and its implications for a more optimistic, 
sustainable future, it is necessary to clarify the use of the term “energy”. 
The focus here is on free energy—energy generated by work that can per-
form further work. Examples of free energy include the kinetic energy of 
atmospheric winds and river currents as well as the chemical energy stored 
in the molecular bonds of carbohydrates. Other examples include power 
generated by transforming the chemical energy in fossil fuels into electricity 
in power plants or transforming solar energy into electrical energy using 
photovoltaics. The energy that human societies need for food and various 
other activities, as indeed does the rest of the biosphere, is free energy. 
Therefore, we need to understand how free energy is generated by the 
Earth system by transforming energy received by the sun and how techno-
logical innovations can help us perform this very same task with a higher 
degree of efficiency.  

This paper is accordingly structured as follows. In the next section (Section 
2), I will start by describing how free energy is generated in general from 
solar forcing. In Section 3, I then describe how photosynthesis generates 



[57] Kleidon 

 

 

free energy from sunlight and provide an explanation as to why it has such 
a low degree of efficiency. This proposition is substantiated using maps 
derived from a simple physical description of this limitation, which can be 
used to provide first-order estimates of the magnitude of free energy gener-
ation by the natural, terrestrial biosphere. In Section 4, I will use an example 
to illustrate how the biosphere has the means to push its physical limits to 
higher levels, thereby altering environmental conditions such that they are 
more conducive to performing photosynthesis and, thus, generating more 
energy to fuel greater activity. This example can substantiate the notion that 
natural systems have a tendency to push their physical limits, which is very 
likely a general feature of an evolving thermodynamic system that may also 
apply to human systems. In Section 5, I will describe the rate of energy con-
sumption by human societies and estimate the level of damage the terrestri-
al biosphere has suffered as a result of human activities. These estimates 
exemplify how important human activity has become as an Earth system 
process in quantitative, physical terms. I will then provide a few examples in 
Section 6 examining how manmade technologies can meet the demands of 
human energy consumption and, at the same time, sustain or enhance the 
activity of the natural biosphere. I will close with a summary and conclu-
sions. 

2. HOW TO GENERATE FREE ENERGY FROM SOLAR FORC-
ING 

Before I describe how photosynthesis generates free energy, it is important 
to define this term briefly, to explain what makes it so different from “just” 
energy and to understand how Earth system processes generate it. Free en-
ergy is simply energy without entropy, capable of performing work, result-
ing in so-called dissipative dynamics. It is sometimes referred to as “exergy” 
(for example, in Hermann 2006). The kinetic energy associated with atmos-
pheric motion is an example of free energy, which is dissipated by friction 
(that is, converted into heat), as is the chemical energy stored in carbohy-
drates and biomass, which is dissipated by metabolisms or by combustion. 
Free energy plays a central role in the dynamics of the Earth system, driving 
the physical dynamics that shape climate, biospheric dynamics with their 
associated food chains, as well as socioeconomic dynamics. These dynamics 
are driven by the dissipation (or consumption) of this free energy, forming 
dissipative systems that are thermodynamically very different from those in 
thermodynamic equilibrium. 

To understand how free energy is generated from solar forcing, we need to 
look at entropy—a key aspect of energy. Entropy was introduced empirical-
ly with the growing popularity of steam engines in the nineteenth century, 



Ecology, Economy and Society–the INSEE Journal [58] 

 

 

to describe how much work could be derived from a heat source. The con-
cept received a physical interpretation due to the work of Boltzmann in the 
late nineteenth century; Planck subsequently extended this theory to apply it 
to the treatment of radiation, together with the notion that energy at the 
atomic scale came in discrete amounts called “quanta”. This set the founda-
tion for the revolution of quantum physics in the early twentieth century. In 
modern physics, entropy plays a key role in describing many facets of the 
quantum world of atoms and molecules in terms of comparatively simple, 
macroscopic characteristics that describe how energy is stored and convert-
ed by solids, liquids, and gases.   

As stated, at the microscopic atomic scale, energy comes in discrete 
amounts called quanta. Energy as radiation is in the form of photons dis-
tributed across different wavelengths, and energy in chemical bonds repre-
sents the discrete distribution of electrons across different atomic shells, 
while heat refers to the random motion, vibrations, or rotations of mole-
cules. All these microscopic aspects are represented by discrete amounts of 
energy being distributed over a finite number of states. They can thus be 
counted and assigned probabilities as to certain ways of distributing these 
quanta of energy across states. At the macroscopic scale, however, we are 
typically not interested in these details. Then, we can assume that a given 
amount of energy is distributed in the most probable way. This is measured 
by entropy, as expressed by Boltzmann’s famous equation, S = k log W, 
where S represents entropy, k is a constant, and W is the number of possi-
ble ways to distribute energy. The assumption of the most probable distri-
bution represents a maximum in entropy and is referred to as the so-called 
thermodynamic equilibrium. Since, at the microscopic scale, energy is dis-
tributed across photons, electrons, and molecules, we have three forms of 
entropy that are important to Earth system science: radiative, molar, and 
thermal entropy. 

Systems become interesting when they are not in equilibrium, and this 
brings us to the concept of free energy. For disequilibrium to occur, we 
need to have differences in entropy. Here, the second law of thermodynam-
ics applies, requiring that whatever will happen, it needs to yield an overall 
increase in entropy. For the Earth system, the major driver for disequilibri-
um is the difference in the kind of radiation that the Earth receives and 
emits to space (Figure 2). At the planetary scale, energy fluxes are roughly 
balanced such that about as much solar radiation enters the Earth system as 
is reflected and emitted to space. But these energy fluxes differ vastly in 
their radiative entropies. Solar radiation is emitted from the sun at a very 
high emission temperature of about 5500°C, which results in radiation with 
short wavelengths, mostly in the visible range, comparatively few photons 



[59] Kleidon 

 

 

of high energy, and very low radiative entropy when this radiation reaches 
the Earth’s orbit. After absorption and further transformation, the Earth 
emits this energy as terrestrial radiation at a much lower radiative tempera-
ture of about -18°C. This radiation is represented by infrared wavelengths, 
many more photons of lesser energy, and thus has a much higher level of 
entropy. This results in a massive thermodynamic disequilibrium between 
the solar radiation the Earth receives and the radiation the Earth emits.  

Figure 2: Planetary Energy Conversions on Earth Are Driven by the Difference in 
Entropy between Solar and Emitted Radiation 

 

Source: Author 

The simplest way to destroy this disequilibrium is to absorb and re-emit 
radiation at a lower temperature. This increases the level of entropy yet 
does not drive dissipative dynamics. More relevant are the cases in which 
this disequilibrium is used to generate free energy. There are various mech-
anisms by which this can be accomplished (yellow boxes in Figure 2); yet, 
the rules for these mechanisms are the same and are set by the laws of 
thermodynamics.  

The physical mechanism to generate free energy can be illustrated by a con-
ventional power plant (Figure 3). Heat is generated by fuel combustion at a 
high temperature, yielding heat at a low entropy level. That it has a low en-



Ecology, Economy and Society–the INSEE Journal [60] 

 

 

tropy level can be seen by Clausius’ expression, which defines a change in 
entropy as ∆S = ∆Q/T, with ∆Q being the heat added or removed and T 
being the temperature (in units of Kelvin) at which heat is exchanged. Since 
combustion occurs at a high temperature, the added level of entropy to the 
power plant is comparatively small. The steam released by the cooling tow-
ers expels some of that heat from the power plant but at much colder tem-
peratures, thus exporting heat with a much higher level of entropy. To fulfil 
the second law of thermodynamics, at least as much entropy must be re-
leased from the cooling towers as is added by combustion. When these en-
tropy fluxes balance each other, with entropy entering the power plant at 
the same rate as entropy exiting through the cooling towers, this yields the 
upper limit on how much energy without entropy can be generated—free 
energy. This limit is known as the Carnot limit. It limits how much work 
can best be performed and how much electricity—free energy in electric 
form—can best be generated by the power plant. 

The physical Earth system operates much like such a power plant. The heat 
source is the absorption of solar radiation at the surface (as opposed to be-
ing released by combustion) and the emission of radiation from the atmos-
phere serves as a cooling tower that exports entropy from the Earth system 
to space in the form of radiation. The work done is that of generating mo-
tion, whether in the form of buoyancy, driving vertical convective motions, 
or horizontally, in the form of regional circulations (such as a sea breeze 
system), even large-scale circulations (such as the Hadley circulation), or 
mid-latitude winds. Comparison to observations indicates that atmospheric 
motion operates at this thermodynamic limit, working as hard as it can 
(Kleidon 2021a). This maximization of power is reflected in characteristic 
surface energy balance partitioning, temperature patterns, and evaporation 
rates that fit very well with observations (Kleidon 2021b).  
 



[61] Kleidon 

 

 

Figure 3: Free Energy Generation by a Power Plant and Its Subsequent Dissipa-

tion by a Dissipative System1 

 

Source: Author. 

This motion then drives other physical processes, such as the generation of 
waves over the ocean, hydrologic cycling, and the production of renewable 
wind energy. Or, it is dissipated back into heat via friction. The work in-
volved is, however, relatively small and the conversion has low efficiency. 
This is because only differences in radiative heating and cooling serve as a 
heat source and the temperature differences are relatively smaller when 
compared to that of a power plant. This amounts to an overall low conver-
sion efficiency of less than 1% of the incoming solar radiation, which is 
converted to free energy as kinetic energy.  
This low conversion efficiency for physical Earth system processes is inevi-
table. Once solar radiation is absorbed by the Earth’s surface and converted 
into heat, most of its low entropy is already lost because the Earth’s surface 

 
1 Illustration of free energy generation using a power plant as an example (as seen 
in the box on the left). The same thermodynamic rules also apply to energy conver-
sions within the Earth system. Once free energy is generated, it drives the dynamics 
of dissipative systems (as seen in the box on the right). 
 



Ecology, Economy and Society–the INSEE Journal [62] 

 

 

is at a much colder temperature than the emission temperature of the sun. 
Absorption thus turns solar radiation into the heat of relatively high entro-
py. The temperature differences when converting this energy further are 
thus set by the difference between the Earth’s surface temperature and the 
Earth’s radiative temperature (for vertical motion) or the difference in tem-
peratures between the tropics and polar regions (for horizontal motion). 
This difference is relatively small (about 33 K) and yields a low conversion 
efficiency.  

Thus, to enhance the conversion efficiency of solar radiation into free ener-
gy, certain mechanisms are necessary to circumvent the intermediate step of 
conversion into heat. Two such alternatives are shown in Figure 2 (in the 
yellow boxes): photosynthesis and photovoltaics. I will now turn to photo-
synthesis, as this is the process by which free energy is generated from sun-
light for dissipative activities within the biosphere. 

3. ENERGY GENERATION BY THE NATURAL BIOSPHERE 
AND ITS PHYSICAL LIMITS 

To evaluate the biosphere’s capacity for converting solar energy into chemi-
cal energy using this thermodynamic approach, the key question is how and 
how much free energy can be generated by photosynthesis, which then con-
strains the level of metabolic activity within the biosphere. Photosynthesis 
is generally described as a chemical conversion process that converts carbon 
dioxide and water into carbohydrates and oxygen, using solar radiation as 
the energy source. The resulting carbohydrates then contain about 40 kJ of 
chemical free energy per gram of carbon. This energy feeds the metabolic 
activities of producers—known as autotrophic respiration—as well as those 
of living organisms—or heterotrophic respiration—which make up the bio-
sphere (Figure 4). This metabolic activity uses the chemical free energy con-
tained in the organic carbon compounds generated by photosynthesis as 
well as oxygen and dissipates this free energy back as heat, thereby produc-
ing entropy. While this examination of photosynthesis does not tell us how 
and how many organisms are being fed by this chemical free energy, its 
generation nevertheless creates thermodynamic disequilibrium (in the form 
of reduced organic carbon compounds and atmospheric oxygen) and it sets 
a limit for dissipative activities within the biosphere. Thus, we will first look 
at the energy conversions involved in photosynthesis in somewhat greater 
detail, estimate their conversion efficiencies, and evaluate whether these 
operate at their thermodynamic limit, just as atmospheric motion does in 
the climate system.  

The first step of photosynthesis involves light reactions in photosystems 
during which light is absorbed. Here, light does not turn into heat—the 



[63] Kleidon 

 

 

random motion of molecules—but instead performs photochemistry as it 
splits water into its compounds and further splits hydrogen into its nega-
tively charged electron and its positively charged nucleus. In other words, 
the photosystems perform the work of charge separation, generating elec-
tricfree energy. Photosynthesis requires about 8–10 quanta of light of wave-
lengths of about 700 nm to split the hydrogen atoms involved in binding 
one molecule of carbon, as described by the well-established concept of 
quantum yield efficiency (Emerson 1958). These quanta carry about 1.8 eV 
of energy each, with 1 eV = 1.6 x 10-19 J being a unit of energy at the quan-
tum scale and the amount calculated by h c / λ, with h ≈ 6.63 x 10-34 J being 
the Planck constant, c ≈ 3 x 108 m s-1 the speed of light, and λ = 700 x 10-9 
m being the wavelength of the photon. Taken together, this yields energy 
from absorbed radiation of about 14.4–18 eV. For comparison, this amount 
is slightly more than the bare minimum of 13.6 eV, which is needed to per-
form the work of charge separation of the hydrogen atom. On a mol basis, 
photosynthesis uses at least Na x 14.4 eV = 1387 kJ mol-1 to split one mol 
of water, with Na being the Avogadro constant, Na = 6.022 x 1023 mol-1. 
Hence, this first step is highly efficient, with a conversion efficiency of 
about 76–94%.  

The generated electric energy is then incorporated into longer-lived chemi-
cal compounds, like NADP and ATP, before these are used (as per the Cal-
vin cycle) to convert this energy further and store it in the form of carbo-
hydrates. This requires carbon dioxide, which needs to be taken in from the 
surrounding air. This particular step is far less efficient. Using the 1,387 kJ 
of energy from the absorbed photons, this cycle produces one mol of car-
bon in the form of glucose with an energy content of merely 480 kJ. This 
corresponds to an overall conversion efficiency (from radiative to chemical 
energy) of 480 kJ/1387 kJ = 34%. Laboratory measurements in low-light 
conditions have found that plants operate close to this efficiency (Hill and 
Rich 1983). When we consider that photosynthesis can only utilize about 
55% of the solar spectrum (photosynthetically active radiation or PAR), the 
efficiency of carbon fixation is reduced to less than 19% for converting the 
energy contained in sunlight into carbohydrates. 

However, observations from terrestrial ecosystems indicate that, in general, 
the efficiency of photosynthetic carbon uptake is substantially lower than 
this efficiency, with values typically falling under the 3% mark (Monteith 
1972, 1977; Kleidon 2021b). This much lower efficiency can be attributed 
to the restrictive role of the gas exchange associated with carbon and water 
between the vegetation canopy and the surrounding air (Kleidon 2021b). 
Vegetation needs to take in carbon dioxide from the air, and while doing so, 
it inadvertently loses water vapour. This gas exchange with the atmosphere 



Ecology, Economy and Society–the INSEE Journal [64] 

 

 

occurs at a relatively fixed ratio of about 2 grams of carbon taken in for 
each kg of water evaporated—the water use efficiency (Law et al. 2002). It 
can be inferred that when we want to identify the primary limitation for 
photosynthesis, and thus for the free energy generation within the bio-
sphere, we need to understand what limits the gas exchange between the 
surface and the atmosphere or the closely associated rate of evaporation. 

Figure 4: Generation and Dissipation of Free Energy by the Biosphere and Its 
Relation to Chemical Disequilibrium 

 

Source: Author 

This brings us back to the restrictive role of thermodynamics, not in terms 
of the energy conversion from sunlight to carbohydrate but in terms of how 
motion is generated, which simultaneously sustains the gas exchange to 
supply vegetation with the carbon dioxide it needs to assimilate and allows 
vegetation to evaporate water into the atmosphere. This evaporation rate 
from the surface to the atmosphere is strongly controlled by thermodynam-
ics when water is sufficiently available and this control enters twice in the 
process. First, when solar radiation heats the surface, it generates buoyancy 



[65] Kleidon 

 

 

and vertical, convective motion. The more updrafts develop, the greater the 
quantity of heat and moisture taken from the surface into the atmosphere 
and carbon dioxide is replenished near the surface. With stronger updrafts, 
however, the surface is cooled more efficiently. This leads to a maximum 
power limit, as in the case of large–scale motion, determining the magni-
tude of turbulent fluxes at the surface. The second instance where thermo-
dynamics acts as a constraint is in the partitioning of the absorbed radiation 
into heating and moistening the near-surface air. At thermodynamic equilib-
rium, this sets up a partition between the sensible and latent heat fluxes, 
known in micrometeorology as equilibrium partitioning. The fluxes drawn 
from these thermodynamic constraints fit very well with observations 
(Kleidon et al 2014; Conte et al 2019). This implies that thermodynamics 
imposes a major constraint on the biosphere through the gas exchange of 
water vapour and, thus, for carbon dioxide, limiting the rate at which the 
terrestrial biosphere can use the absorbed solar energy in photosynthesis to 
generate chemical-free energy. 

I illustrate this reasoning with data from continental-scale estimates of the 
energy balance and the water and carbon cycles (Stephens et al 2012; Oki 
and Kanae 2006; Beer et al 2010) and then go into greater detail using global 
radiation and precipitation datasets (Loeb et al. 2018; Kato et al 2018; Adler 
et al 2016), as in Kleidon (2021b). Continental evaporation is estimated to 
be about 66 x 1012 m3/a (Oki and Kanae 2006). If we assume that the ma-
jority of evaporation takes place through the vegetative cover and apply the 
mean water use efficiency as 2 gC/kg H2O, we obtain a gross photosynthet-
ic uptake of 131 x 1015 gC/a. This estimate corresponds with the estimate 
of 123 x 1015 gC/a by Beer et al (2010). Bearing in mind that each gram of 
carbon contains about 40 kJ of energy in the form of carbohydrates, this 
corresponds to a power of 152 x 1012 W. When we then divide this power 
by the 165 W m-2 of energy absorbed as solar radiation at the surface (Ste-
phens et al 2012) and the land area (29% of 511 x 1012 m2), we obtain a 
mean efficiency of 0.6% of the photosynthetic land carbon uptake. This 
confirms the very low efficiency by which the biosphere generates free en-
ergy from sunlight, as mentioned earlier. 

This estimate is, of course, very rough, as it neglects, for example, variations 
in water availability across regions. These drawbacks can be seen when this 
analysis is conducted spatially using global datasets. Such an analysis is rep-
resented in Figure 5 using annual means, as in Kleidon (2021b) and as 
summarized in Table 1. This estimate uses the absorbed solar radiation at 
the surface (Figure 5a) from the CERES global radiation dataset (Loeb et al 
2018; Kato et al 2018) as the starting point, estimates evaporation from the 
maximum power limit without water limitation (the so-called potential 



Ecology, Economy and Society–the INSEE Journal [66] 

 

 

evaporation rate, as seen in Figure 5b) and uses the mean precipitation rate 
(Figure 5c) taken from the GPCP dataset (Adler et al. 2016) to restrict evap-
oration in the presence of water availability, thus yielding the so-called actu-
al evaporation rate (Figure 5d). 

Figure 5: Maps of (a) Mean Annual Solar Radiation, (b) Potential Evaporation, (c) 
Precipitation, and (d) Actual Evaporation Estimated by the Maximum Power Limit 
and Water Availability 

 
 
Source: Author  
 

Applying the observed mean water use efficiency value to the thermody-
namically–derived evaporation rate then yields an estimate for the photo-
synthetic carbon uptake and its associated thermodynamic conversion effi-
ciency (Figure 6). We can see that there are clear variations in efficiency 
among regions, with humid regions indicating a greater efficiency of up to 
3%, while desert regions have no marked productivity due to the lack of 
water there. This supports the well–established notion that water availability 
is a major issue for the terrestrial biosphere, shaping the spatiotemporal 



[67] Kleidon 

 

 

patterns of its productivity. What this estimate implies is that the limits set 
by gas exchange and water availability can clearly explain the observed pat-
terns of carbon uptake in the terrestrial biosphere. 

Figure 6: Maps of (a) Mean Annual Photosynthetic Carbon Uptake and (b) Ther-
modynamic Efficiency Estimated from the Evaporation Rate Shown in Figure 5 

Source: See Footnote2  

To conclude this discussion on free energy generation by the terrestrial bio-
sphere, it should be noted that thermodynamics does not act directly to 
limit energy conversions from sunlight to carbohydrates. After all, photo-
systems are highly efficient when it comes to the first step to converting 
solar energy. It would seem, then, that it is the rate of gas exchange that 
limits photosynthetic carbon uptake, as it provides the necessary supply of 
carbon dioxide from the surrounding air. This interpretation can explain the 
very low efficiency in observed photosynthetic carbon uptake rates within 
natural ecosystems. It represents an indirect thermodynamic constraint that 
requires an Earth system view, which describes biosphere productivity as a 
process that is intimately linked to, and constrained by, physical transport 
processes within the Earth’s environment. 

 

 
2 After Kleidon (2021b), uptake (via photosynthesis) of terrestrial vegetation is estimated 
from constant water use efficiency and the thermodynamically constrained evaporation rate 
as shown in Figure 5(b). The thermodynamic efficiency with regard to converting absorbed 
solar radiation into chemical free energy is based on Kleidon (2021b). 

 



Ecology, Economy and Society–the INSEE Journal [68] 

 

 

Table 1: Summary of Annual Mean Estimates of Energy-, Water-, and Carbon 
Fluxes Described in the Text  

 

Natural limits of terrestrial productivity 

Absorbed 
solar radiation 

141 W/m2 

20,726 TW 
Calculated directly from CERES (Loeb et al 
2018; Kato et al 2018). Shown in Figure 5a. 

Potential 
evaporation 

2.84 mm/day 
153 x 103 
km3/year 
12,091 TW 

Calculated from the maximum power limit and 
thermodynamic equilibrium partitioning using 
CERES forcing. 

Precipitation 2.18 mm/day 
117 x 103 
km3/year 

Calculated directly from GPCP (Adler et al 
2016). 

Evaporation 1.65 mm/day 
88 x 103 
km3/year 
7,015 TW 

Calculated by gauging the minimum of poten-
tial evaporation and precipitation at the annual 
scale. Shown in Figure 5d. Compare to the 
observed estimate of 66 x 103 km3/year (Oki 
and Kanae 2006). 

Gross primary 
productivity 
(Net photo-
synthesis) 

405 
gC/m2/year 
177 GtC/year 
224 TW 

Calculated by converting evaporation to car-
bon uptake with a fixed water use efficiency of 
2 gC/kg H2O. Shown in Figure 6a. Compare 
to the observed estimate of 120 GtC/year 
(Beer et al 2010). 

Net primary 
productivity 
(Biomass pro-
duction) 

202 
gC/m2/year 
89 GtC/year 
112 TW 

50% dissipation by autotrophic respiration by 
plants. 

Pushing the limits using seasonal soil water storage 

Evaporation 
without sea-
sonal water 
storage 

1.47 mm/day 
79 x 103 
km3/year 
6244 TW 

Calculated by presupposing that monthly 
evaporation is the minimum of potential 
evaporation and precipitation (i.e., no seasonal 
water storage). 

Enhancement 
by vegetation 

0.18 mm/day 
+12% 
9 x 103 
km3/year 
711 TW 

Calculated by presupposing that evaporation is 
the minimum of potential evaporation and 
precipitation at the annual scale (i.e., seasonal 
water deficits are compensated by water stor-
age variations within the rooting zone). 



[69] Kleidon 

 

 

Enhancement 
of net primary 
productivity 

25 gC/m2/year 
+12% 
10 GtC/year 
12 TW 

Converted with a fixed water use efficiency of 
2 gC/kg H2O. 

Human appropriation of productivity 

Absorbed 
solar radiation 

111 W/m2 

5,449 TW 
The weighted average over the cropland and 
pastures as shown in Figure 7. 

Evaporation 1.38 mm/day 
24.8 x 103 
km3/year 
1,963 TW 

The weighted average over the cropland and 
pastures as shown in Figure 7. 

Net primary 
productivity 

503 
gC/m2/year 
25 GtC/year 
31 TW 

Calculated by converting evaporation to car-
bon uptake with a fixed water use efficiency of 
2 gC/kg H2O. Reduced by 50% dissipation via 
autotrophic respiration by plants. 

Pushing limits using technology 

Runoff poten-
tially available 
for irrigation 
and additional 
evaporation 

0.53 mm/day 
29 x 103 
km3/year 
+32% 

Difference between current climatological 
precipitation and evaporation on land. 

Enhancement 
of terrestrial 
net primary 
productivity 

193 
gC/m2/year 
28 GtC/year 
36 TW 
+32% 

Calculated by converting evaporation to car-
bon uptake with a fixed water use efficiency of 
2 gC/kg H2O. Reduced by 50% dissipation via 
autotrophic respiration by plants. 

Area needed 
for photovol-
taics to gener-
ate current 
human prima-
ry energy de-
mand of 18 
TW 

550 000 km2 Calculated using the global mean absorption 
of solar radiation of 165 W m-2 and photovol-
taic efficiency of 20%. 



Ecology, Economy and Society–the INSEE Journal [70] 

 

 

Area needed 
for generating 
as much 
freshwater by 
seawater de-
salination as is 
currently in 
continental 
runoff 

177 000 km2 Calculated using an energy demand of 4 kJ per 
litre of desalination using membrane technol-
ogy and energy generation by photovoltaics, 
using 165 W m-2 and an efficiency of 20%. 

Source: Author 

 

4. THE BIOSPHERE PUSHES ITS LIMITS 

While these constraints limit the activity of the terrestrial biosphere, the 
latter nevertheless acts and affects the environment in such a way that 
pushes these limits further to achieve higher levels of activity. The means 
and mechanisms employed are different compared to the atmospheric heat 
engines described above. This relates to the effects biotic activity has on the 
environment and the consequences of these for the conditions required to 
generate and dissipate free energy. The overall dynamics surrounding the 
concept of “pushing the limit” appear to reflect, nevertheless, the same un-
derlying evolutionary dynamics as the physical dynamics of the climate sys-
tem: to maximize power and dissipation. 

To illustrate this push, I will take the example of the depths of the rooting 
zone of vegetation and its effects. As plants grow, they allocate some of 
their energy to growing rooting systems in the soil. A deeper rooting zone 
allows them to access a greater amount of the water stored in the soil for 
evaporation, particularly during dry periods. These periods are characterized 
by potential evaporation exceeding the rate of precipitation. Water stored 
within the soil can be used to compensate for this lack of precipitation in-
put, allowing vegetation to maintain evaporation during such periods.  

By building root systems and enhancing soil water storage, the biosphere 
benefits by elongating the period over which gas exchange can be main-
tained and productivity sustained. It thus makes the biosphere more pro-
ductive. However, this enhancement is not infinite but limited by the clima-
tological water balance. In humid regions with dry periods, vegetation needs 
only to store the water required to overcome the water deficit during the 
dry season. In arid regions, vegetation cannot store more water than the 
water surplus during the wet season. The required water storage volume 
needed for this seasonal compensation reproduces the observed rooting 



[71] Kleidon 

 

 

depths in different vegetation types quite well (Kleidon and Heimann 1998). 
Figure 7 illustrates these considerations, using monthly mean fields of pre-
cipitation and the thermodynamically–constrained evaporation estimate to 
infer the actual evaporation rate in the absence of seasonal water storage 
and its enhancement through soil water storage facilitated by root systems. 
This effect of rooting systems enhances terrestrial carbon uptake by roughly 
10% (Table 1), increasing the power and dissipative activity of the terrestrial 
biosphere. 

Other biotic effects can act similarly to enhance terrestrial productivity. 
Vegetated surfaces are typically darker (they have a lower surface albedo) 
than bare ground, enhancing surface heating as a driver for gas exchange, 
an aspect that has not been considered here. The highly heterogeneous 
canopies of forested surfaces represent a much greater leaf surface area, 
which facilitates a higher rate of gas exchange. Stomates, small openings in 
the leaves which regulate gas exchange, can vary in size and number and 
operate to maximize the carbon gain while water is evaporated by the leaves 
(Cowan and Farquhar 1977; Medlyn et al 2011). This means enhancing 
productivity comes with environmental consequences, such as enhanced 
moisture recycling on land. On longer time scales, the activity of the bio-
sphere has profoundly altered the atmospheric composition and the 
strength of the greenhouse effect, changing the planetary disequilibrium 
state and energy fuels for the biosphere (Judson 2017). These effects all 
influence the physical environment and provide means to maximize free 
energy generation further, resulting in environmental conditions that sustain 
the current high (possibly even maximized) levels of biotic activity on the 
planet. Even though the means by which the biosphere would achieve this 
maximization are very different from physical heat engines, the outcome 
would be the same: to maximize free energy generation and its dissipation. 

 



Ecology, Economy and Society–the INSEE Journal [72] 

 

 

Figure 7: Effects of deep-rooted vegetation on evaporation and associated gas 
exchange as an example of how the biosphere pushes its limits 

Source: Author  

5. HUMAN SOCIETIES AS ADDITIONAL ENERGY DISSIPA-
TION PROCESSES 

Let us now turn to human activity as a thermodynamic Earth system pro-
cess. To do so, we must start with the consumption of free energy, which is 
at the very core of human existence as well as our socioeconomic activities. 
Humans need energy to sustain their metabolism, just like any other living 
organism. This energy comes in the form of the food we eat as reflected in 
the calories that food contains (1 cal = 4.184 J). As this energy is consumed 
by metabolic activity, it converts the chemicalfree energy associated with 
the disequilibrium of carbohydrates and oxygen back into carbon dioxide, 
water, and heat. Likewise, human societies consume free energy mostly in 
the form of chemical energy stored in fossil fuels. Upon combustion, this 
free energy is converted into heat and subsequently into work, for example, 
by generating motion, electricity, or transforming materials. Thus, primary 
energy consumption correlates strongly to economic activity (e.g., Cleveland 
et al 1984; Ayres and Nair 1984). Viewing human activity primarily through 
the lens of energy allows us to describe it as a dissipative Earth system pro-
cess and place it into the same thermodynamic framework we utilized 
above for physical and biotic Earth system processes. Using this frame-
work, we will evaluate whether human activity acts to deplete or enhance 
the dissipative activity of the biosphere and link this to sustaining the bio-
sphere. 



[73] Kleidon 

 

 

Human activity dissipates the free energy generated by the Earth system, 
specifically the chemicalfree energy generated through photosynthesis. Pho-
tosynthesis fuels the plants grown in agriculture and the resulting products 
feed livestock and human metabolisms. A fraction of the productivity of 
the biosphere is thus appropriated by agricultural activities. This share—the 
human appropriation of net primary productivity (Vitousek et al. 1986; 
Haberl, Erb, and Krausmann 2014)—is considerable, estimated to be 13–
25% of the total terrestrial productivity. The free energy associated with this 
productivity is thus diverted to direct or indirect human use, such as food 
production, feeding livestock, or biofuel production. It is no longer availa-
ble to the natural biosphere, reducing its level of dissipative activity and 
sustaining fewer natural living organisms. 

To illustrate the magnitude of human appropriation using the aforemen-
tioned estimates, I used the land cover datasets provided by Ramankutty et 
al (2008) as masks to describe where terrestrial productivity is appropriated 
by human use, either in croplands or rangelands (Figure 8). The estimate of 
carbon uptake shown in Figure 6a was reduced by 50% to account for the 
metabolic activity of the producers (the autotrophic respiration) and then 
summed up over the areas of human land use, yielding the estimates shown 
in Table 1. It indicates that in these human-dominated areas, about 31 TW 
(or 28%) of the net primary productivity on land takes place—an estimate 
that is consistent with the more elaborate estimates by Haberl, Erb, and 
Krausmann (2014). It must be noted, however, that at present, not all of 
this energy is appropriated for human use, as some of it feeds natural graz-
ers (or “pests”) or is used in the decomposition of belowground organic 
carbon by soil organisms that also draw from this free energy to sustain 
their metabolisms. Yet, with the intensification of agricultural activity, 
which aims at increasing yield, this will inadvertently result in a greater share 
of human appropriation instead of feeding the natural biosphere. We can 
thus anticipate that with agricultural expansion and intensification, the trend 
of greater appropriation will continue, depleting the likelihood of feeding 
the dissipative activity of the natural biosphere further.  

The consumption of primary energy due to socioeconomic activities repre-
sents further energy consumption by human societies. At present, this con-
sumption amounts to about 18 TW, which is mostly consumed in the form 
of fossil fuels. This chemical energy was generated by photosynthesis in the 
Earth’s geological past, followed by the subsequent burial of a fraction of 
the resulting biomass by geologic processes, thus creating the chemical dis-
equilibrium of hydrocarbons in the geological reservoirs and atmospheric 
oxygen. Using fossil fuels depletes this disequilibrium. It increases the at-
mospheric concentration of carbon dioxide, enhances the associated green-



Ecology, Economy and Society–the INSEE Journal [74] 

 

 

house effect, and causes global warming. Irrespective of these global ef-
fects, fossil fuels are a finite resource and their use (at current rates) is not 
sustainable. If, for simplicity’s sake, we were to assume that this use of en-
ergy was being replaced by appropriating more of the net primary produc-
tivity as an energy resource (for example, firewood or biofuels), this would 
draw away another substantial fraction of the free energy available to the 
natural biosphere. Thus, this would further deplete the ability to sustain the 
dissipative activity of the natural biosphere. 

Figure 8: Human Impact on the Terrestrial Biosphere as Reflected by Its Land Use 
in Croplands and Rangelands 

 

Source: Datasets from Ramankutty et al. (2008) 

This description of human activity as an additional dissipative Earth system 
process suggests that more human activity would inevitably come at the 
expense of diminished biospheric activity. Since terrestrial productivity op-
erates at its limit, the total consumption of the generated free energy to ei-
ther sustain the dissipative activity of the natural biosphere or human activi-
ty is fixed and appears to be a zero-sum game. It seems to imply that the 
only way to improve and sustain the conditions of the natural biosphere 
would be for human societies to consume less energy. 

6. TECHNOLOGY PUSHES THE LIMITS TO HIGHER LEVELS 

There is another route by which to sustain the biosphere and that relates to 
mechanisms that may “push the limit”, which is similar to how the bio-
sphere pushes its limits. This involves certain types of manmade technolo-



[75] Kleidon 

 

 

gies. Examples of existing technologies include the use of river water for 
irrigation in arid regions or the damming of water flow to form reservoirs 
for irrigation during dry periods. This makes water available for enhancing 
plant productivity at places or times in which the precipitation input is too 
low to meet the potential evaporation rate. The additional water made avail-
able through the use of these technologies can act to enhance productivity 
by supplementing the means of storing and redistributing water that was 
previously unavailable to the natural biosphere. This water can then push 
the limit of productivity to a higher level by making more water available. 

A look at Table 1 gives us a broad estimate of the magnitude by which such 
technologies could, in principle, enhance terrestrial productivity by storing 
or redistributing water. If we consider all of the continental river discharge 
(or runoff), which, in the climatological mean, balances the difference be-
tween precipitation and evaporation on land and make it available for evap-
oration by storing or redistributing it, this would enhance continental evap-
oration by 32%. Utilizing the water use efficiency for conversion into a 
productivity increase, as was done before, would yield about three times as 
much productivity enhancement due to the seasonal water storage main-
tained by deep-rooted vegetation. What is not accounted for here are possi-
ble climate effects. The enhanced evaporation would result in more conti-
nental moisture recycling, cloud cover, and precipitation, thus altering the 
environmental conditions on land. Nevertheless, this example is put for-
ward simply to indicate that existing technology can provide alternative 
means to enhance productivity and its human appropriation that does not 
come at the cost of appropriating more of the natural productivity of the 
biosphere. 

When we look into the future, a far greater effect can be achieved with 
modern technology. Photovoltaics provides technology that generates free 
energy directly from sunlight much more efficiently than heat engines or 
photosynthesis can achieve. Solar radiation is directly converted into elec-
tricity, avoiding the inevitable, irreversible losses through conversion into 
heat. Thus, photovoltaics is much more efficient than heat engines of the 
atmosphere. Additionally, energy generation by photovoltaics is not con-
strained by gas exchange and water availability, as is the case for photosyn-
thesis—because photovoltaics exports its free energy in the form of elec-
tricity—and does not require gas exchange. With photovoltaics, human so-
cieties can become producers of free energy for the Earth system and 
thereby decouple their demand from the supply by the biosphere. In other 
words, human societies can sustainably grow further for some time but this 
does not need to come at the expense of the biosphere. 



Ecology, Economy and Society–the INSEE Journal [76] 

 

 

It would require relatively little area to meet the current demands for prima-
ry energy using photovoltaics. With a typical efficiency of about 20% for 
solar panels and a mean absorption of solar radiation of 165 W m-2, it 
would merely require about 550,000 km2 or less than 0.4% of the land sur-
face to meet the current primary energy consumption. The use of photovol-
taics would thus eliminate the pressure imposed due to meeting the primary 
energy consumption via the appropriation of energy from the biosphere, 
such as fossil fuels or biofuels, or via the renewable energy generated direct-
ly or indirectly by the heat engines of the atmosphere, such as wind or hy-
dropower. 

This novel supply of primary energy can then be supplemented by other 
technologies to alleviate other natural limits of the biosphere, particularly 
the ones imposed by water availability. Seawater desalination using mem-
brane technologies requires a very small fraction of the energy involved in 
the natural desalination process using evaporation and subsequent precipita-
tion. While it takes about 2.5 MJ to evaporate and desalinate a litre of sea-
water—known as the latent heat of vaporization—membranes only require 
about 4 kJ to achieve the same result (Elimelech and Phillip 2011). To put 
these numbers in a global perspective, at present, it requires 3650 TW of 
solar energy or 3% of the absorbed solar radiation to evaporate water to 
feed the net convergence of moisture transport to land of 46 x 103 km3 per 
year (Oki and Kanae 2006; estimate in Table 1 is 29 x 103 km3 per year). To 
obtain the same freshwater production rate by seawater desalination using 
membrane technology, it would require 6 TW of energy, which could be 
achieved by photovoltaics installed over 177,000 km2 of area (using global 
means). 

These are, of course, rough estimates that do not take into account the 
many practical challenges that must be overcome to make this a reality. 
Changing the terrestrial hydrologic cycle at this magnitude would result in 
climatological changes, likely enhancing continental precipitation. Yet, the 
observation I wish to put forward with these estimates is that there are 
manmade technologies already available that can achieve the outcome of 
natural processes with much greater efficiency. This, in turn, could decou-
ple the growth in food and energy needs of human societies from their nat-
ural sources, decreasing the magnitude of appropriation while potentially 
resulting in positive feedback on photosynthetic carbon fixation (cf. Figure 
1). This decoupling could reduce the impact on the natural biosphere by 
allowing it to use its free energy to feed the dissipative activity of its natural 
food webs and thus sustain the activity of the natural biosphere at higher 
levels. 



[77] Kleidon 

 

 

7. A SUSTAINABLE FUTURE FOR THE TERRESTRIAL BIO-
SPHERE 

I used a thermodynamic Earth system perspective to evaluate how the ac-
tivity of the natural biosphere could be sustained in the presence of increas-
ing human activities. I first reviewed the application of thermodynamics to 
indicate to what extent it restricts the physical functioning of the climate 
system and, thereby, the activity of the terrestrial biosphere. This results in a 
basic trade-off: increased human appropriation of energy seems to come at 
the cost of reducing the dissipative activity of the natural biosphere. The 
solution to this dilemma is by using novel technology, particularly photo-
voltaics. This allows human societies to generate free energy from sunlight 
more efficiently than we do by using natural means, particularly unproduc-
tive areas that are currently not generating free energy, such as deserts. The 
use of this energy can then decouple human energy needs from the supply 
by the natural biosphere. It is through this decoupling that human activity 
could, in principle, grow sustainably to some extent, with this growth com-
ing not at the expense of shrinking the natural biosphere further but by 
providing a possibility to sustain and even enlarge the natural biosphere in 
the Anthropocene.  

Such a trajectory of sustainable growth would likely lead to quite a different 
physical environment. When this energy is used to generate more resources, 
such as freshwater, to extend agriculture into arid regions instead of further 
deforesting humid regions, it would simultaneously strengthen hydrologic 
cycling and alter the physical climate system. Yet, human activities consume 
energy at rates of a similar magnitude to natural processes. It is hard to im-
agine that this consumption could voluntarily be drastically reduced in the 
future. With this impediment, it would seem inevitable that to preserve the 
natural biosphere, the only option left to human societies would be to “en-
large” the biosphere into areas that are not currently productive, such as 
desert regions, to sustain the dissipative activity of the natural biosphere at 
current levels. 

I hope that this energy-oriented view of the biosphere and sustainability of 
human activity at the very large planetary scale can serve as a useful model 
for practical applications to evaluate human interactions and how detri-
mental or beneficial these may be for the natural biosphere to persist in 
times of greater human influences. 

DATA AVAILABILITY 

The datasets used to create the figures and to make the estimates shown in 
Table 1 are available at https://doi.org/10.17617/3.F0Q6X2 . 

https://doi.org/10.17617/3.F0Q6X2


Ecology, Economy and Society–the INSEE Journal [78] 

 

 

 

REFERENCES 

Adler, Robert, Jian-Jian Wang, Matthew Sapiano, George Huffman, Long Chiu, 
Ping-Ping Xie, Ralph Ferraro, et al. 2016. “Global Precipitation Climatology Project 
(GPCP) Climate Data Record (CDR), Version 2.3 (Monthly).” NOAA National 
Centers for Environmental Information. https://doi.org/10.7289/V56971M6. 
Ayres, Robert U, and Indira Nair. 1984. “Thermodynamics and Economics.” Physics 
Today 37: 62–71. https://doi.org/10.1063/1.2915973.  
Beer, Christian, Markus Reichstein,

 
Enrico Tomelleri,

 
Philippe Ciais,

 
Martin Jung, 

Nuno Carvalhais,
 
Christian Rödenbeck, et al. 2010. “Terrestrial Gross Carbon Di-

oxide Uptake: Global Distribution and Covariation with Climate.” Science 329 
(5993): 834–838. https://doi.org/10.1126/science.1184984.  
Clarke, Andrew, and Kevin J Gaston. 2006. “Climate, Energy and Diversity.” Pro-
ceedings of the Royal Society B 273 (1599): 2257–2266. 
https://doi.org./10.1098/rspb.2006.3545.  
Cleveland, Cutler J, Robert Costanza, Charles A S Hall, and Robert Kaufmann. 
1984. “Energy and the U.S. Economy: A Biophysical Perspective.” Science 225 
(4665): 890–897. https://doi.org/10.1126/science.225.4665.890.   
Conte, Luigi, Maik Renner, Paulo Brando, Claudinei Oliveira dos Santos, Divino 
Silvério, Olaf Kolle, Susan E Trumbore, and Axel Kleidon. 2019. “Effects of Trop-
ical Deforestation on Surface Energy Balance Partitioning in Southeastern Amazo-
nia Estimated from Maximum Convective Power.” Geophysical Research Letters 46 (8): 
4396–4403.   https://doi.org/10.1029/2018GL081625.   
Cowan, Ian R, and Graham D Farquhar. 1977. “Stomatal Function in Relation to 
Leaf Metabolism and Environment.” Symposia of the Society for Experimental Biology 31: 
471–505.  

Currie, David J,
 
Gary G Mittelbach, Howard V Cornell, Richard Field, Jean-

Francois Guégan, Bradford A Hawkins, Dawn M Kaufman, et al. 2004. “Predic-
tions and Tests of Climate-based Hypotheses of Broad-scale Variation in Taxo-
nomic Richness.” Ecology Letters 7: 1121–1134. https://doi.org/10.1111/j.1461-
0248.2004.00671.x.  

Elimelech, Menachem, and William A Phillip. 2011. “The Future of Seawater De-
salination: Energy, Technology and the Environment.” Science 333 (6043): 712–717. 
https://doi.org/10.1126/science.1200488.  

Emerson, Robert. 1958. “The Quantum Yield of Photosynthesis.” Annual Review of 
Plant Physiology 9: 1–24. https://doi.org/10.1146/annurev.pp.09.060158.000245.  

Haberl, Helmut, Karl-Heinz Erb, and Fridolin Krausmann. 2014. “Human Appro-
priation of Net Primary Production: Patterns, Trends, and Planetary Boundaries.” 
Annual Review of Environment and Resources 39: 363–391. 
https://doi.org/10.1146/annurev-environ-121912-094620.  

Hermann, Weston A. 2006. “Quantifying Global Exergy Resources.” Energy 31 
(12): 1685–1702. https://doi.org/10.1016/j.energy.2005.09.006. 

https://doi.org/10.7289/V56971M6
https://doi.org/10.1063/1.2915973
https://doi.org/10.1126/science.1184984
https://doi.org./10.1098/rspb.2006.3545
https://doi.org/10.1126/science.225.4665.890
https://doi.org/10.1029/2018GL081625
https://doi.org/10.1111/j.1461-0248.2004.00671.x
https://doi.org/10.1111/j.1461-0248.2004.00671.x
https://doi.org/10.1126/science.1200488
https://doi.org/10.1146/annurev.pp.09.060158.000245
https://doi.org/10.1146/annurev-environ-121912-094620
https://doi.org/10.1016/j.energy.2005.09.006


[79] Kleidon 

 

 

Hill, Robert, and Peter R Rich. 1983. “A Physical Interpretation for the Natural 
Photosynthetic Process.” Proceedings of the National Academy of Sciences 80 (4): 978–
982. https://doi.org/10.1073/pnas.80.4.978.  

IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem 
Services). 2019. “Summary for Policymakers of the Global Assessment Report on 
Biodiversity and Ecosystem Services of the Intergovernmental Science-Policy Plat-
form on Biodiversity and Ecosystem Services.” IPBES. Germany. 
https://doi.org/10.5281/zenodo.3553579.  

Judson, Olivia P. 2017. “The Energy Expansions of Evolution.” Nature Ecology & 
Evolution 1 (0138). https://doi.org/10.1038/s41559-017-0138.  

Kato, Seiji, Fred G Rose, David A Rutan, Tyler J Thorsen, Norman G Loeb, David 
R Doelling, Xianglei Huang, William L. Smith, Wenying Su, and Sueng-Hee Ham. 
2018. “Surface Irradiances of Edition 4.0 Clouds and the Eart’s Radiant Energy 
System (CERES) Energy Balanced and Filled (EBAF) Data Product.” Journal of 
Climate 31 (June): 4501–4527. https://doi.org/10.1175/JCLI-D-17-0523.1. 
Kleidon, Axel. 2021a. “Physical Limits of Wind Energy Within the Atmosphere 
and its Use as Renewable Energy: From the Theoretical Basis to Practical Implica-
tions.” Meteorologische Zeitschrift 30 (3): 203–225. 
https://doi.org/10.1127/metz/2021/1062.   

———. 2021b. “What Limits Photosynthesis? Identifying the Thermodynamic 
Constraints of the  
Terrestrial Biosphere Within the Earth System.” Biochimica et Biophysica Acta (BBA) - 
Bioenergetics 1 (1862). https://doi.org/10.1016/j.bbabio.2020.148303.   

Kleidon, Axel, and Martin Heimann. 1998. “A Method of Determining Rooting 
Depth from a Terrestrial Biosphere Model and its Impacts on the Global Water 
and Carbon Cycle.” Global Change Biology 4 (3) (March): 275–286. 
https://doi.org/10.1046/j.1365-2486.1998.00152.x.  

Kleidon, Axel, Maik Renner, and Phillip Porada. 2014. “Estimates of the Climato-
logical Land Surface Energy and Water Balance Derived from Maximum Convec-
tive Power.” Hydrology and Earth System Sciences 18: 2201–2218. 
https://doi.org/10.5194/hess-18-2201-2014.  

Law, Beverly E, Eva Falge, Lianhong Gu, Dennis D Baldocchi, Peter Bakwin, P 
Berbigier, Kenneth Davis, A Johannes Dolman, et al. 2002. “Environmental Con-
trols over Carbon Dioxide and Water Vapor Exchange of Terrestrial Vegetation.” 
Agricultural and Forest Meteorology 113 (1–4): 97–120. 
https://doi.org/10.1016/S0168-1923(02)00104-1.  

Loeb, G Norman, David R Doelling, Hailan Wang, Wenying Su, Cathy Nguyen, 
Joseph G Corbett, Lusheng Liang, Cristian Mitrescu, Fred G Rose, and Seiji Kato. 

2018. “Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced 
and Filled (EBAF) Top-of-Atmosphere (TOA) Edition 4.0 Data Product.” Journal 
of Climate 31 (2): 895–918. https://doi.org/10.1175/JCLI-D-17-0208.1.  

Meadows, H Donella, Dennis L Meadows, Jørgen Randers, and William W Behrens 
III. 1972. The Limits to Growth: A Report for the Club of Rome’s Project on the Predicament 
of Mankind. New York: Universe Books. 

https://doi.org/10.1073/pnas.80.4.978
https://doi.org/10.5281/zenodo.3553579
https://doi.org/10.1038/s41559-017-0138
https://doi.org/10.1175/JCLI-D-17-0523.1
https://doi.org/10.1127/metz/2021/1062
https://doi.org/10.1016/j.bbabio.2020.148303
https://doi.org/10.1046/j.1365-2486.1998.00152.x
https://doi.org/10.5194/hess-18-2201-2014
https://doi.org/10.1016/S0168-1923(02)00104-1
https://doi.org/10.1175/JCLI-D-17-0208.1


Ecology, Economy and Society–the INSEE Journal [80] 

 

 

Medlyn, Belinda E, Remko A Duursma, Derek Eamus, David S Ellsworth, I Colin 
Prentice, Craig V M Barton, Kristine Y Crous, Paolo de Angelis, Michael Freeman, 
and Lisa Wingate. 2011. “Reconciling the Optimal and Empirical Approaches to 
Modelling Stomatal Conductance.” Global Change Biology 17 (6): 2134–2144. 
https://doi.org/10.1111/j.1365-2486.2010.02375.x.  

Monteith, John Lennox. 1972. “Solar Radiation and Productivity in Tropical Eco-
systems.” Journal of Applied Ecology 9 (3): 747–766. 
https://doi.org/10.2307/2401901.  

———. 1977. “Climate and the Efficiency of Crop Production in Britain.” Philo-
sophical Transactions of the Royal Society B 281 (980): 277–294. 
https://doi.org/10.1098/rstb.1977.0140.  

Oki, Taikan, and Shinjiro Kanae. 2006. “Global Hydrological Cycles and World 
Water Resources.” Science 313(5790): 1068–1072. 
https://doi.org/10.1126/science.1128845.  

Ramankutty, Navin,
 
Amato T Evan,

 
Chad Monfreda,

 
and Jonathan A Foley. 2008. 

“Farming the Planet: 1. Geographic Distribution of Global Agricultural Lands in 
the Year 2000.” Global Biogeochemical Cycles 22 (1). 
https://doi.org/10.1029/2007GB002952.  

Stephens, L Graeme, Juilin Li, Martin Wild, Carol Anne Clayson, Norman Loeb, 

Seiji Kato, Tristan L’Ecuyer, Paul W Stackhouse Jr, Matthew Lebsock,
 
and Timo-

thy Andrews. 2012. “An Update on Earth’s Energy Balance in Light of the Latest 
Global Observations.” Nature Geoscience 5: 691–696. 
https://doi.org/10.1038/NGEO1580.  

Vitousek, Peter M, Paul R Ehrlich, Anne H Ehrlich, and Pamela A Matson. 1986. 
“Human Appropriation of the Products of Photosynthesis.” BioScience 36 (6): 368–
373. https://doi.org/10.2307/1310258.  

 

https://doi.org/10.1111/j.1365-2486.2010.02375.x
https://doi.org/10.2307/2401901
https://doi.org/10.1098/rstb.1977.0140
https://doi.org/10.1126/science.1128845
https://doi.org/10.1029/2007GB002952
https://doi.org/10.1038/NGEO1580
https://doi.org/10.2307/1310258

