It’s easy enough to find definitions of the principles and goals of sustainability. It is less easy to envision what actions either promote or hinder achievement of sustainability.

The International Brundtland Commission Report of 1987 issued a widely quoted definition: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”

I often say that it means practices we can continue indefinitely without causing harm to the environment, the economy, or to people.

But how can we determine what practices are indeed sustainable? An international initiative called The Natural Step defines four core systemic conditions for a sustainable society in a way we can actually form a practical mental image.

Metaphors

The Natural Step presents two important metaphors to help us understand the problems and suggest directions toward solutions.

First, the current model of development resembles a funnel. Right now, worldwide, the demand for and consumption of resources has outgrown nature’s ability to replenish. As demand increases, capacity to meet it declines. Over time, societies move to the narrower part of the funnel, where there are fewer options. We need to open the funnel.

Second, we are beginning to recognize that we must examine whole systems, how everything works together. Consider a tree. For any large system, the trunk and branches of a tree represent the core framework, the basic operating principles of the system.

The leaves represent the details. To reword a familiar cliché, we can’t afford to be like someone who can’t see the tree because of all the leaves.

If the funnel represents how we damage nature by systematically increasing demands on it, the tree trunk represents areas where we must stop this systematic increase.

The Natural Step has worked out four principles it considers both necessary and enough to achieve sustainability. They apply to any scale of any activity, and they do not overlap.

The repeated use of the phrase “systematic increase” explicitly means that the principles do not include prohibitions of any of the actions described. A sustainable society can still cut down trees, mine for metals, eat fish, and so on. It just can’t keep doing so past nature’s ability to replenish.

Extraction of substances

“To become a sustainable society we must eliminate our contributions to 1) the systematic increase of concentrations of substances extracted from the Earth’s crust (for example, heavy metals and fossil fuels).”

The Earth’s crust is the outer layer that we live on. We share it with other animals and plants. We have cut down trees, eaten and clothed ourselves with animals and animal products and depended on the soil to grow crops for millennia.

Humans have extracted resources from beneath the surface from the first time anyone recognized the usefulness of metals. In addition to ancient metals like iron, copper, gold, and silver, we have in recent centuries identified and found uses for mercury, zinc, platinum, aluminum, and many others. The Earth’s crust provides its substances in limited amounts.

We have already used up all of the petroleum and natural gas in North America that is easily accessible. And so we must engage in more expensive processes and more hazardous activities like deep sea drilling and fracking in order to extract any more.

Concentration of substances

“To become a sustainable society we must eliminate our contributions to 2) the systematic increase of concentrations of substances produced by society (for example, plastics, dioxins, PCBs and DDT).”

If you have ever read about ancient practices for tanning leather or making metal alloys, you know that humanity has a long history of making and using noxious substances in unsafe working conditions.

Today, we have greater concern for workplace safety, but the number and scale of manmade substances has greatly increased over the past century, or even the past few decades.

Unlike manmade substances of the past, the ones The Natural Step explicitly mentions do not naturally break down and become something else. Plastic breaks down into smaller and smaller pieces, but remains plastic. We do not yet know all of the ecological consequences of all the little bits of plastic in soil, rivers, or oceans. What we do know is troublesome.

Dioxins, a family of toxic and often carcinogenic chemicals, basically have no use whatsoever. PCBs (polychlorinated biphenyls) used to be manufactured in large quantities until banned in 1977. Otherwise no one manufactures them. They are unintended byproducts of combustion that first pollute the air and then settle on land and in water.

From there they enter the food supply and bioaccumulate. That is, just like mercury, organisms low on the food chain ingest them. They remain in the bodies of organisms higher on the food chain and never go away. Levels of dioxins in the environment have declined since the banning of PCBs, but not enough for exposure levels to remain a concern. Most people have detectable levels in their bodies.

Physical degradation of nature

“To become a sustainable society we must eliminate our contributions to 3) the systematic physical degradation of nature and natural processes (for example, over harvesting forests, destroying habitat and overfishing).”

Cape Cod in Massachusetts was named for a fish that seemed to be in infinite supply. Not any more. Cod is but one kind of fish subject to severe restrictions on fishing and not the most seriously overfished.

Much of the world used to be covered with trees. Too often, in recent years, people have clear-cut trees in order to put the land to other uses. Adverse environmental consequences of deforestation are too numerous even to begin to describe in this post.

Trees and fish are renewable resources, but not if they are harvested or destroyed at a rate beyond their capacity to reproduce. How can any society thrive after the last tree has been cut down and the last edible fish eaten?

Basic human needs

” To become a sustainable society we must eliminate our contributions to 4) conditions that systematically undermine people’s capacity to meet their basic human needs (for example, unsafe working conditions and not enough pay to live on).”

Sustainability is often described as having three pillars: environmental, economic, and social. The Natural Step’s principles do not directly address economic sustainability, but they do make the point that environmental sustainability cannot happen apart from social sustainability.

• Everyone’s living conditions are viable with a combination of environmental and economic sustainability—at least until social unrest overwhelms it.
• Everyone’s living conditions are bearable with a combination of environmental and social sustainability—at least until they all run out of money to keep it going.
• Everyone’s living conditions are equitable with a combination of social and economic sustainability—at least until the environment degrades to a point that the earth can no longer sustain life.
• Everyone’s living conditions are sustainable only where the three basic kinds of sustainability intersect.

Social sustainability doesn’t require the absence of unemployment, hunger, or violence. It doesn’t require the elimination of all social inequality. These problems are hardwired into human nature. All human society at any time or any place on earth has included some kind of evil exploitation of the weak by the strong.

But today, we can no longer think of any one society as unrelated to all or most others on the planet. Social sustainability means that regardless of social class or nationality, no one finds it impossible to meet their basic needs.

So far, this post has described the trunk and branches of the tree. We mustn’t neglect the leaves. Probably no one of us can relate to the daunting task of keeping the entire tree of sustainability healthy. But we can envision a cluster of leaves along one small branch.

We can look out for the sustainability of our own individual lifestyle and the community in which we live. We can be mindful of people across the world—or across town—that suffer from inequality and injustice. We can remember that everyone is interconnected with everyone else. We can think globally and act locally.

We will have a sustainable world when we all take responsibility for our own part in opening the funnel by greening our lifestyles — when sustainability does not seem like something for some diffuse and indefinable “them” to do, but rather something concrete and visible for “us” to do.

Photo credits.
Circle of hands. Source unknown
Tree. Photo by David M. Guion
Plastic bottles. Some rights reserved by Paul Simpson.
Deforestation. Some rights reserved by Daniel Beilinson