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A.
A simple view
Many environmental problems appear to have
simple causes and effects; for example:See Diagram (Table)
https://i.servimg.com/u/f40/11/10/02/04/a10.jpg
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A broader & deeper view
Most environmental problems have complex
causes & consequences; for instance:See Diagram (Table)
https://i.servimg.com/u/f40/11/10/02/04/b_10.jpg
C.
Downstream and upstream effects
In the above diagram only the effects of
plastic bottles accumulating are noted, that is, downstream from or after
the stress of accumulation.
Processes that precede and lead
to the piling up of plastic bottles may also have significant environmental
effects. These may be called upstream effects.
In the above example, what upstream effects might we identify,
in addition to the downstream effects which are diagrammed in the model?
To answer the question, first try to list the major processes that must
occur in order for plasic bottles to accumulate. Then attempt to
determine the environmental consequences of each of these necessary upstream acts.
For instance:
| Some processes necessary for plastic bottles to pile up | Some environmental effects of such action-- upstream effects |
| Extract petroleum from which to make plastics | Oil spills |
| Make petrochemicals | Air pollution, water pollution |
| Make plastic bottles | Air pollution, electricity use |
| Ship containers to bottler | Transportation impacts |
| Produce beverages (contents) | Resource use for contents |
| Bottle beverages | Impacts of making and operating bottling equipment |
| Truck beverages to retailer | Transportation impacts, including energy use |
| Store beverages at retailer | Energy used for lights, refrigeration, store operation |
| Purchase and consume contents | Possible health effects |
| Dispose of plastic bottle (after one use!) | Energy and other costs of handling waste bottles |
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The environmental costs of another everyday product: French fries!
A written description, but analogous to
our model in terms of sifting out important effects of a common practice-- eating commercial french fries--
is online for you to read. It is condensed from a chapter in Stuff;
The Secret Lives of Everyday Things, by John C. Ryan and A.T. Durning,
1997, Northwest Environmental Watch, Seattle. The book also analyzes the
environmental costs of coffee, newspaper, T-shirt, shoes, bike and car,
computer, hamburger, and cola.
E.
Further complexity in the model
Despite our "broader and deeper"
view of causes and effects of environmental stress, reality is usually much
more complex that such models suggest. Webs of cause-and-effect
linkages are more realistic than an isolated, linear chain of links.
A major fault with our linear model is that it largely fails to recognize feedback loops, whereby one factor influences other processes, which in turn interact and circle back to change the initial factor. This dynamic interaction and feedback is inherent in nearly all environmental issues, but it is virtually impossible to comprehend in detail. Using computers, extremely complex models with thousands of interacting variables are sometimes employed in an attempt to simulate and understand real-world problems. Such models are beyond our consideration in this course.
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