Donald G Rogich and Grecia R Matos

Movements and transformations, material flows, in the environment are continuous. These can be driven by solar energy and geologic processes, or by living organisms which are part of the natural environment. They can also be the result of human activity. All movements and transformations cause change, and these changes may or may not be compatible with sustaining the environmental conditions that exist. Where changes in one part of an ecosystem are useful to, or reversed by, another component of the same system, the system will remain in balance because the cycle of change is closed. With the exception of energy from the sun, natural systems have closed cycles, things that die and decay, the outputs from one part of the system, produce the nutrients for other living things, which in turn provide the basis for new growth. In contrast, the majority of the outputs from industrial activities have no utility to any other part of the environment, they are wastes, and the cycle of change is open: 'the industrial system is an open one in which nutrients are transformed into "wastes", but not significantly recycled. The industrial system, as it exists today, is therefore ipso facto unsustainable' (Ayres and Ayres 1998).

When humans lived as hunter-gatherers they were part of the closed natural system. With the rise of agriculture and the creation of concentrated settlements (cities), they began to live in more open systems, separate at first, but increasingly interconnected. The material flows (movements and transformations of physical material) associated with our emerging open systems grew slowly until the advent of the industrial revolution about 300 years ago, at which time they began to increase exponentially in the countries which were industrializing. Currently, material flows in the USA exceed 20 billion metric tons per year, about 80 tons of material for every person in the country. However, the USA is not alone; studies (Adriaanse et al. 1997; WRI 1997) have shown that the material flows in Germany, Japan, the Netherlands and Austria are of equal per capita magnitude. We are busy creatures, and we are changing our environment.

Figure 22.1 presents a conceptual model of material flow in an industrial economy. In this representation inputs are obtained from the domestic environment, and outputs are returned to it. These actions modify the domestic environment. Imports from, and exports to, other countries affect the environment in the country where they are created and disposed. The inputs from the environment are renewable or non-renewable (created in geologic time) resources and pre-existing landforms. Landforms, which are modified to increase their economic utility, change the environment in a 'permanent' manner. Resource inputs extracted from the environment move through a material cycle to a stage where they are ready for use. At each point in this cycle there are process outputs (some of these flows may be recaptured, on the basis of economic and technical considerations)

and losses which are a consequence of inefficiencies in the process. After going through all the necessary processing stages the material enters the use stage, where the residence time can vary considerably depending on the material and its use. Some flows result in 'permanent' additions to the stock of built infrastructure; others are discarded after only days or years of useful life. The use of materials such as fertilizers and pesticides results in an immediate, dissipative, release to the environment. As shown in Figure 22.1, some process wastes and post-use discards may be recaptured, and re-used as inputs. The recapture of material flows emitted in process is not always feasible, and those used in a dissi-pative manner are not recoverable. While in economic terms the value added to the material is consumed by use, the physical material, often in a changed form, continues to exist after it exits from the economy.

Renewable and non- INPUTS FROM Existing renewable resources ENVIRONMENT landforms

Renewable and non- INPUTS FROM Existing renewable resources ENVIRONMENT landforms

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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