John C. Ayers is a Professor of Earth and Environmental Sciences at Vanderbilt University. As a geochemist he specializes in sustainability and also the chemistry of natural waters.
The following is the introductory chapter for a book Professor Ayers is writing titled “Sustainability: Reducing Risk and Living Well in a World of Shrinking Resources”.

There is enough in the world for everyone’s need, but not enough for everyone’s greed. – Frank Buchman
I know of no restorative of heart, body, and soul more effective against hopelessness than the restoration of the Earth. – Barry Lopez, Helping Nature Heal
I start with a fanciful retelling of the story of Adam and Eve that comes closer to telling the true story of humans on earth: When Adam and Eve ate from the Tree of Knowledge, they gained not only knowledge but also an insatiable appetite. They used their knowledge to harvest all of the resources in the Garden of Eden and built a large mansion to isolate them from nature. Eventually Eden, which supplied all of their needs, became a wasteland. Because they did not act as good stewards of nature as God commanded, and instead consumed all of the resources, they lost their home and were forced to move to more marginal lands in order to survive. They were not forced by God to leave Eden; they destroyed Eden.
The concept of sustainability didn’t become concrete until the U.N. World Commission on Environment published “Our Common Future” in 1987. The report is often referred to as the “Brundtland Report” because the Commission was chaired by the female Norwegian prime minister Gro Harlem Brundtland. They defined sustainable development as development that “meets the needs of the present without compromising the ability of future generations to meet their needs [9].” It therefore concerned intragenerational and intergenerational equity.
We use a different approach to define sustainability. In general use, sustainability refers to the long-term ability to maintain an ecosystem or human society. Here we define the sustainable state of a system as one that can be sustained indefinitely; this is characterized as a steady state in which the amounts of various types of capital (economic, environmental, and social) remain unchanged because inputs equal outputs. Sustainability is a balance between supply and demand, between what is produced and consumed. When the amount of resources we consume equals the amount we produce, we are “net zero”. A home is sustainable if it consumes no more resources than it produces. Thus, it is net zero for energy, water, and food.
Since to achieve sustainability we must not only achieve this balance between supply and demand (inflows and outflows), but also decrease the amount of waste produced so as not to exceed the waste absorption capacity of the environment, we must also apply the “net zero” concept to waste. We must strive to produce zero waste by closing resource loops. We must produce as much resource as we consume, and we must consume as much waste as we produce. How do we consume waste? By treating it as a resource and finding ways to use it. We must change our practices so that nature can continue to sustain us.
True sustainability requires zero growth of population and the economy. Because sustainable development requires development, which is synonymous with growth, the phrase is actually a contradiction. Sustainable development is preferable to unsustainable development, but it cannot create sustainability (Ehrenfeld). Ehrenfeld uses the term “flourishing”, being healthy and living the good life, as a symbol of sustainability, and this is a symbol we can aspire to as individuals and as a society.
Thus, it is not enough to stop unsustainable practices; we must create new, sustainable practices. This type of thinking is exemplified in McDonough and Braungart’s very influential book “Cradle to Cradle” (2002). They argue that we can do more than just reduce pollution and waste. Our approach should be not to just reduce our negative impacts, but in fact create positive effects, and move from being “eco-efficient to eco-effective”. McDonough and Braungart (2010) encourage businesses to use sustainable design to make products that will enhance economic, environmental, and social health. Products should be designed so that at the end of their life cycles they will become food rather than waste, i.e., that they be biodegradable. Rather than taking up space in a landfill, smart products can be converted into soil by microorganisms. This is true recycling, not downcycling in which the product is recycled into a degraded form. The Cradle to Cradle (C2C) approach advocates that human industrial systems be designed using biomimicry, i.e., by mimicking natural cycles in which nutrients (resources or materials) are safely circulated in closed loops.
In a sustainable state, there is no risk of running out of resources such as food or water. Thus, a sustainable state is also the state of minimum risk to current and future generations. Sustainable living minimizes risk for individuals and their offspring. We can never completely eliminate risk, but we can greatly reduce it by reducing the probability of running out of essential resources (food, water, and energy) and of being exposed to a harmful environment. We will discuss how to reduce the following types of risk: economic, shortages of food, water, and energy, global climate change, pollution, and natural hazards.
Humans consciously and unconsciously make decisions in order to avoid pain. Thus, we can go a step further and say that the motivation for sustainable living is to reduce risk in order to avoid pain. Sustainable living is a risk and pain avoidance strategy that increases our odds of survival and of propagating our genes. When risks such as natural resource shortages were in the distant future, the motivation to achieve sustainability was altruistic.
Cold hard facts version: Sustainability is a risk and pain avoidance strategy. It increases our odds of survival and of propagating our genes.
All of the advice in this book can be considered as a strategy to minimize your risk as an individual. When this strategy is adopted by all of the members of a community, that community will become sustainable. What is a sustainable community? It is a community that is designed to maximize and maintain social, economic, and environmental capital. They have reduced the level of danger and increased survival rate and therefore longevity by securing multiple reliable, sustainable sources of water, food, and energy. They conserve these resources and use them efficiently. These actions minimize risk and make the community autonomous and self-reliant.
A sustainable community also reduces waste and pollution by closing resource loops, reusing materials when possible and recycling them when not. They have a high-quality education system so that everyone in the community can make informed choices. People are healthy because they all spend time performing manual labor such as organic gardening and they are not exposed to harmful chemicals. This means that as workers they remain productive for a long time. The community guarantees quality health care and a minimum wage above the poverty level. Because everyone has the physical resources they need (remember to distinguish need from want), it is rare for individuals to engage in crime or for the community to engage in war (only in self-defense). With low risk levels, individuals have less anxiety and experience less stress. This and a sense of community further improve the physical and psychological health of the community, and reduce costs for physical and mental health care. Is this Utopia? Not necessarily. Perhaps everyone is living at the subsistence level. However, as a community they have achieved more than our society, especially in the U.S. Great wealth does not seem to have reduced risk in the U.S., and it certainly hasn’t reduced anxiety or stress.
Important components of sustainability are illustrated in Fig. 1.

Fig. 1
As shown in the figure, the three pillars of sustainability are Social, Economic, and Environmental (or the equivalent three P’s: People, Prosperity, and the Planet). A more accurate figure makes clear that in fact the economy is a subset of society, which is a subset of the environment.

Fig. 1a
We cannot have a healthy, sustainable economy without a sustainable society, which in turn requires a sustainable environment. As we’ll discuss below, our human population continues to increase at an exponential rate, which requires us to accommodate that growth in our temporary plans. However, we must remember that exponential rates of change of any kind are unsustainable and lead to unstable systems. To provide for growth in a sustainable fashion we must engage in sustainable development, which will allow us to leave future generations the capacity to live as well as we do today (Brundtlandt Commission), but at the same time we must decrease the rate of growth until it drops to zero.
Sustainability can also be defined as the preservation of economic, environmental, and social capital for future generations. Preserving capital requires reducing economic, environmental, and social risk. Capital is preserved when the rate of consumption (demand) is not greater than the rate of production (supply). Sustainability can be achieved through conservation and efficient use of capital, build capital reserves, using triple bottom line accounting to keep track of all three types of capital, and diversifying by adding redundancy to capital supply systems. We will explore these strategies throughout this book.
Social, economic, and environmental sustainability require that society preserve or increase the amounts of social, economic, and environmental capital defined as follows (modified from [97]):
Social capital:
Includes human, social, and institutional capital. “Human capital includes the health, skills and knowledge embodied in people, as well as the physical ability to do work. Human capital can be enhanced through education and training, and through improved nutrition and physical and mental health. Social and institutional capital includes networks of relationships between people, rules and governance arrangements, and shared norms and culture. Social capital contributes to well-being directly, such as through relationships and sense of identity. It also has an important role in facilitating the coordination and use of other forms of capital to promote human well-being.” Institutions such as employers or the government can preserve or increase social capital by providing support services such as childcare, counseling, and rehabilitation of criminals.
Economic capital:
(often referred to as “Produced” capital, which is sometimes split into physical and financial capital): “includes tools and equipment, buildings, books, vehicles, and physical infrastructure such as roads, bridges, pipes and powerlines. This group also includes financial assets and access to credit and insurance, which are essential components of household livelihood strategies and regional or national development success.”
Environmental capital:
“includes all environmental resources and processes that provide value to people, such as food, fiber, clean air and water, energy and waste processing. It also includes non-renewable resources, such as minerals, oil and coal.”
Sustainable strategies maintain all three types of capital through effective use, protection, and diversification of assets. For example, beauty is an asset, and like all assets it must be used and protected. In the movie Monty Python and the Holy Grail, the father lists for his son the assets of a prospective spouse: “she’s beautiful, rich, she’s got huge (gestures to indicate her breasts, then thinks better)”¦tracts of land”. But beauty is fleeting, so the person who is fortunate to be beautiful can use that beauty to diversify their assets and build social and economic capital. Some beauties make the mistake of relying solely on beauty, which increases their risk: what happens if an accident or old age steals their beauty? They must diversify their assets to reduce their risk. If a person lacks physical beauty, they must rely on other assets such as intelligence or wealth in order to build their assets, diversify, and reduce risk. Throughout this book we will examine strategies for effectively using, protecting, and diversifying social, economic, and environmental capital in order to reduce risk.
To protect social, economic, and environmental capital, society must rely only on the interest and not the principal in each category. The interest is the renewable portion, and it shouldn’t be used faster than the rate of renewal. Fiscal conservatives use this approach to achieve economic sustainability. Relying on renewable resources (interest) rather than non-renewable resources (principle) allows us to achieve both economic and environmental sustainability.
“One approach to sustainable development, described as weak sustainability, assumes that it is possible to compensate for a reduction in one type of capital (typically reduced natural capital) with an increase in another type of capital (typically produced capital). This approach defines sustainability in terms of an increase in the total value of the aggregate capital stock. Strong sustainability, by contrast, argues that substitution is not always possible between different types of capital. It is widely accepted, for example, that natural capital is special, as the loss of specific natural assets–such as a species–is usually irreversible, and that other types of capital cannot provide perfect substitutes or compensation for the reduced or lost functions or ecosystem services. Similar arguments apply to social capital, which is difficult to repair if lost. [97]“
“The sustainable development debate is based on the assumption that societies need to manage three types of capital (natural, economic, and sociopolitical), which may be non-substitutable and whose consumption might be irreversible (ibid.).” For example, economic capital cannot necessarily substitute for social or natural capital. Furthermore, social and natural degradation may be irreversible. Thus, in this book we advocate strong sustainability, in which sustainable development and sustainable maintenance require that the books for all three pillars of sustainability be balanced independently.
One of the main messages of this book is that our society will experience resource shortages in the near future because we have been using these resources unsustainably, either because they are nonrenewable or because we used renewable resources faster than they could be replenished. Some resources will become of short supply within the lifetimes of my generation (baby-boomers). Others will become scarce during the lifetimes of our children. To understand this problem, we must introduce some terms and concepts. Natural processes can replace renewable resources, but can’t replace non-renewable resources, or replace them at such a low rate that we essentially have a fixed supply of them. Non-renewable resources are fixed in quantity, so the faster you use them, the faster they run out. Fossil fuels fall into this category because it takes millions of years for nature to produce oil and coal from plants. In general, we are more at risk of running out of non-renewable resources. However, we can also run out of renewable resources if we use them much faster than they are replaced. For example, marine fisheries are collapsing worldwide because overfishing has decreased the populations of certain fish species to critically low levels or even caused them to become extinct. If left alone to breed they may regenerate their populations to preexisting levels, but that could take many decades. You may have noticed that certain species of fish such as cod have essentially disappeared from grocery shelves; this is because the commercial catch of cod has declined rapidly in recent years, to the point where in the year 2000 the World Wide Fund for Nature (WWF) added cod to its list of endangered species, stating that the worldwide cod catch had decreased 70% in the preceding 30 years, and was at risk of becoming extinct within 15 years. Environmentally-minded consumers should avoid eating cod, as the cod-fishing industry is unsustainable.
Fig. 1b Resource Pools shows how the amount of a resource can grow or shrink, depending on the relative rates of replenishment (input) and extraction (output). Our cod example is of type (b), where the rate of extraction exceeds the rate of replenishment. Resources that fall in this category are the ones we must be concerned about, and we will examine many examples, particularly water. In case (a), the rate of input equals the rate of output, and we have what’s called a steady-state in which the amount of resource available for use remains constant. Steady-state systems are stable because they don’t change with time. The sustainable approach to managing renewable resources is to harvest the resource at the same rate it is produced, maintaining a steady state. Sustainable use of renewable resources is desirable because it guarantees long-term availability of those resources.
For individuals, sustainability is almost synonymous with self-reliance, and for communities it is synonymous with autonomy. In developing countries individuals and communities can’t rely on their government to provide necessities like clean water. Even when countries develop enough infrastructure to deliver necessities to homes, service may not be completely reliable. For a critical resource like fresh water that families can only live a few days without, it makes sense to learn to have back-up plans if services are interrupted briefly (e.g., a storm-induced outage) or permanently (due to energy shortages or war). Your plans for providing resources for your family should have some built-in redundancy, and provide for both temporary and permanent interruption of services. For example, plans for a temporary water shortage could involve long-term storage of water in barrels. If the service interruption is expected, you can fill your bathtub and other large containers with water before the water is shut off. For long-term or permanent interruption, you must have a plan to use natural sources of water, which should include rainwater collection and purification. The primary duty of parents is to provide for their children; you must learn self-sufficiency so that you can provide for your family even if the government can no longer help you.
Citations
1. Dresner, S., The Principles of Sustainability. 2nd ed. 2008, London, UK: Earthscan. 205.ISBN: 978-1-84407-496-9.
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