MarkSustainability in ecological time is a bit like a neglected indoor swimming pool that will eventually become an ugly, green puddle. It is subject to nature’s laws which we have tried to bend. The injection of exogenous energy in the fossil fuel pulse has allowed humans to reproduce and use resources way beyond the earth’s natural capacity to capture and cycle energy and nutrients.
Conventional wisdom has sustainability meaning “the ability to be maintained at a certain rate or level“. This can translate to ‘keep going’ so that constancy is maintained.
This idea is attractive because it implies opportunity and survival compared to the alternative of decline or collapse. Maintained also suggests it is always possible—whatever “it” might be will continue forever.
The snag is that nature still needs to get the memo.
She does not stay the same ever. Instead, nature is constantly in flux through a fantastic ability to adapt and bend with whatever environmental changes happen.
Nature must be flexible and change because all ecological processes are governed by basic thermodynamics.
Let’s consider sustainability from these laws of nature to understand why the typical definitions of sustainability are misleading and find ecological time a much better option, especially for sustainable food and the global challenge of feeding everyone well..
Sustainability with thermodynamics?
What happens if we look at sustainability via the laws of thermodynamics?
Polish-American chemical engineer and physicist Tadeusz Patzek goes back to nature to find a definition of sustainability that considers basic physics.
Patzeks definition of sustainability is
A cyclic process is sustainable if and only if (i) It is capable of being sustained, i.e., maintained without interruption, weakening or loss of quality ‘forever,’ and (ii) The environment on which this process feeds and to which it expels its waste is also sustained forever.
Professor Tadeusz Patzek
Forever is not what nature does.
Natural processes decay because they must comply with the Second Law of Thermodynamics, which is the tendency of natural processes to lead towards spatial homogeneity of matter and energy, especially of temperature.
Physicists measure this with entropy. In an isolated thermodynamic system left to spontaneous evolution, entropy cannot decrease with time, and isolated thermodynamic systems always arrive at a state of thermodynamic equilibrium, where the entropy is highest.
In short, nature decays.
Even great mountain ranges are eroded to flat plains, weakening the power of water to erode.
Here is the fantastic part.
Biology is a system to defy entropy, at least for a time. Organisms are thermodynamic systems that stave off entropy using energy to put off the inevitable thermodynamic equilibrium for as long as it takes to grow and reproduce.
Organisms maintain complex internal and external organisation using energy to do it. Humans do this for our bodies with energy from food, but we have also managed to capture exogenous energy, first with fire and then fossils. Extra energy maintains our environments for the best comfort and convenience.
What about waste—complications from the first law of thermodynamics
The first law of thermodynamics states that when energy passes into or out of a system (as work, heat, or matter), the system’s internal energy changes in accordance with the law of conservation of energy.
And the law of energy conservation states that an isolated system’s total energy remains constant; it is said to be conserved over time—energy can neither be created nor destroyed, only be transformed or transferred from one form to another.
If defying entropy uses energy, then that energy must go somewhere. It dissipates into the environment. Organisms are waste machines. Because the earth is finite, it cannot be a bottomless pit for waste materials or energy.
The organism does not perceive the waste. In real-time, it just happens, apparently without consequence.
Nor does the organism perceive the finite.
Sustainability is impossible for an organism that defies entropy and generates waste.
Standard definitions of sustainability
Presumably, thermodynamics was not considered in the social definition of sustainability provided in 1987 by the United Nations Brundtland Commission and most commonly cited by proponents:
Meeting the needs of the present without compromising the ability of future generations to meet their own needs.
Here sustainability seems to be about avoiding the depletion of natural resources to maintain an ecological balance and has something to do with intergenerational equity—a colossal challenge thermodynamically.
In crude terms, keep what you have today so future generations can use the resource.
But sustain means to keep going, not to stop.
Popular definitions assume that resource use is a given because humanity needs food, water and shelter sources. Each person has that divine right to use resources for our needs directly from our DNA. Resource use is what we do.
In practice, most sustainability responses proposed to date conserve, not abstain. Turn off the lights, change incandescent bulbs to LEDs, reduce waste, and recycle plastics, with a host of ‘saving’ actions. These make us feel good because we can do something ourselves but still need to tackle the longer-term challenge of resource use.
And so we arrive at ecological time.
The real challenge—sustainability in ecological time
In a word, time.
Use without using up is acceptable in a moment. But what if that is a year, a generation, or 100 years?
Since we started using crude oil in earnest, the total consumption will reach about 1.65 trillion barrels (roughly 262 trillion litres) by 2022, 11% of it in the last five years.
As I write, it is December 2022, and the estimate for global oil consumption is 97 million barrels a day, with a projected increase to 104 million per day by 2026.
At the current yearly consumption of 35.4 billion barrels, humanity will use another 1.65 trillion barrels in just 47 years—1.65 trillion barrels is the volume of proven oil reserves worldwide as of 2016.
This rate of energy use cannot meet a thermodynamic definition of sustainability.
We are already cooking under the waste energy.
And what else happened to all that exogenous energy from fossils? We made more people—we eat and drink fossil fuels—so turning the fossil fuel pulse into a population spike.
In ecological time, typically decades to centuries, where organisms interact with the environment, humans have appropriated external energy sources to inflate our population artificially and ecologically overshoot to consume more resources than there are available.
Ecological time for our species is longer than a human lifetime and much longer than a product cycle or the term of office of the elected. We tend not to think about it.
We are as blind to sustainability in ecological time as we are energy blind.
An impossible sustainability nirvana
The consequence of being blind to sustainability in ecological time is that we ignore thermodynamics, especially the second law.
Until 12,000 years ago, nature was a vast human playground, an endless landscape of opportunity. There was no way a tribe of our hunter-gatherer ancestors could imagine there was a limit so long as they kept moving. A handful of the lucky ones living on the shores of lakes or river banks or next to the ocean did not even have to move very far.
What they knew was daily, seasonal and yearly change. Nature was cycling around them, coming and going with the tides and the weather.
Water flows over the waterfall and always will. The falls cascade only after storms or during the rainy season, and it can be down to a trickle in the dry season. Severe winters might cause the water to freeze. No constancy then, but water flows sustainably over the waterfall.
When humans invented agriculture, initially, little changed. A few sedentary cultures came and went, but most humans still had to move around on what must have felt like a vast empty planet.
Resources were scarce, but they replenished themselves, and the water went over the waterfall.
Then when agriculture became the dominant source of food—the energy source to power human bodies so they can defy entropy—the fields and grasslands were a net energy source. The sun’s energy and some human and animal labour went in, and the food came out.
At a planet-scale this was similar to what happened before agriculture when the vegetation fixed the sun’s energy and the animal biodiversity processed and cycled it along with nutrients.
In principle, agriculture that mimicked nature as a net energy source with internal cycling of nutrients met sustainability in ecological time. It wasn’t all that different to the ecology that had been going on through evolutionary time since plants first colonised the land 470 million years ago.
The second law still applies—isolated thermodynamic systems always arrive at a state of thermodynamic equilibrium, where the entropy is highest—but nature had been defying this law all along by cycling energy and nutrients and absorbing the energy waste. It is the miracle of life.
In ecological time, nature appeared consistent, stable even.
But the reality was that the waste released from all the energy use was filling up the earth’s capacity to absorb the excess energy.
Early agriculture changed the balance. Most fields are less productive and less ecologically efficient than natural vegetation. They are also designed to export energy and nutrients to the human population, who increasingly consume them away from farms. Some additional waste energy dissipated into the atmosphere when the vegetation was cleared for the fields.
Then came the Haber-Bosch process and the mechanisation of agriculture to deliver an exponential increase in the use of nitrogen fertiliser. This new, intensive agricuture was a huge energy sink. More energy went in than came out as food, even though the amount coming out was huge and was converted into a population spike. But thermodynamics still applies to the energy added, it heads for thermodynamic equilibrium.
Where did the waste energy go? Into the sink that is the planet. It had nowhere else to go.
Ecological time
At sustainably FED we focus on ecological time.
As a rule of thumb, this is 10s to 100s of years, typically longer than a human life but not long enough for the climate to shift. Periods where there is a predictability to what nature will do.
Ecological time is perhaps easily imagined as the generation time of the longest-living organism in a habitat, more often than not, that will be a tree.
Several spotted gum trees in my garden will live for 200 or more years.
Each will experience numerous fires, droughts, and occasional flooding. Hundreds of strong winds, storms, frosts, and high temperatures will occur.
Each tree will be utilized by any number of organisms across its lifetime.
Its roots will spread out through the soil to stabilize the tree as it gets larger often up to 30 or more metres in height and steadily, those roots will remove nutrients from the soil carried up to the leaves using the process of transpiration.
Whilst the house was placed in my backyard 30 years ago, the trees have been around a lot longer than that. The ecological time frame of my garden is likely to outlive most of my house’s features.
Ecological time is longer than you think. Ecological processes operate beyond people’s lifetime and many of the structures they create.
How to interpret ecological time
Here are some simple rules of thumb to figure out an ecological time for your own backyard
- Get to know the ecological system
- Find out the driver’s of that system
- Look for cycles in those drivers or patterns in the system
- Find out what disturbs the system and how often do those disturbance occur
- Try to understand changes in the structure composition and function of the ecological system
All this is a kind of “ecological read”, an interpretation not just of what you see but how it works and changes over time.
If you need a specific number—a period of ecological time for your system—look to the longest-lived organism and use its lifetime as the rule of thumb.
Typically it will be from 100 years to a millennium.
Getting to a number gives you a time frame against which to assess actions that are considered sustainable, recalling that sustainability requires no change.
An impossible sustainability nirvana
The consequence of being blind to sustainability in ecological time is that we ignore thermodynamics, especially the second law.
Until 12,000 years ago, nature was a vast human playground, an endless landscape of opportunity. There was no way a tribe of our hunter-gatherer ancestors could imagine there was a limit so long as they kept moving. A handful of the lucky ones living on the shores of lakes or river banks or next to the ocean did not even have to move very far.
What they knew was daily, seasonal and yearly change. Nature was cycling around them, coming and going with the tides and the weather.
Water flows over the waterfall and always will. The falls cascade only after storms or during the rainy season, and it can be down to a trickle in the dry season. Severe winters might cause the water to freeze. No constancy then, but water flows sustainably over the waterfall.
When humans invented agriculture, initially, little changed. A few sedentary cultures came and went, but most humans still had to move around on what must have felt like a vast empty planet.
Resources were scarce, but they replenished themselves, and the water went over the waterfall.
Then when agriculture became the dominant source of food—the energy source to power human bodies so they can defy entropy—the fields and grasslands were a net energy source. The sun’s energy and some human and animal labour went in, and the food came out.
At a planet-scale this was similar to what happened before agriculture when the vegetation fixed the sun’s energy and the animal biodiversity processed and cycled it along with nutrients.
In principle, agriculture that mimicked nature as a net energy source with internal cycling of nutrients met sustainability in ecological time. It wasn’t all that different to the ecology that had been going on through evolutionary time since plants first colonised the land 470 million years ago.
The second law still applies—isolated thermodynamic systems always arrive at a state of thermodynamic equilibrium, where the entropy is highest—but nature had been defying this law all along by cycling energy and nutrients and absorbing the energy waste. It is the miracle of life.
In ecological time, nature appeared consistent, stable even.
But the reality was that the waste released from all the energy use was filling up the earth’s capacity to absorb the excess energy.
Early agriculture changed the balance. Most fields are less productive and less ecologically efficient than natural vegetation. They are also designed to export energy and nutrients to the human population, who increasingly consume them away from farms. Some additional waste energy dissipated into the atmosphere when the vegetation was cleared for the fields.
Then came the Haber-Bosch process and the mechanisation of agriculture to deliver an exponential increase in the use of nitrogen fertiliser. This new, intensive agricuture was a huge energy sink. More energy went in than came out as food, even though the amount coming out was huge and was converted into a population spike. But thermodynamics still applies to the energy added, it heads for thermodynamic equilibrium.
Where did the waste energy go? Into the sink that is the planet. It had nowhere else to go.
Science source
Carroll, S. P., Hendry, A. P., Reznick, D. N., & Fox, C. W. (2007). Evolution on ecological time‐scales. Functional Ecology, 21(3), 387-393.
Patzek, T. W. (2004). Thermodynamics of the corn-ethanol biofuel cycle. Critical Reviews in plant sciences, 23(6), 519-567.
Hero image from photo by Darla Hueske on Unsplash
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