SummingAny given environmental problem may have a variety of components
that score differently for the same descriptor. For example, in the case of
Stratospheric Ozone Depletion, persistence times of some CFCs are 10
years whereas others are 110 years. As a result, a summing rule has been
chosen for each descriptor, as noted throughout and explained below:
|1. ||Total: add up over all components;|
|2. ||Highest Significant Score: give the highest score for which a significant
portion of the problem would score (significant portion is defined as
about 20 per cent);|
|3. ||Weighted Average: take a weighted average over all components of the
Material flux descriptors
1. Spatial Extent
This measures the spatial extent of a single release or event for which
there is a significant change in the material levels in the environment. The
quantitative scale is based on linear dimensions, whereas the categorical
scale is on common geographical units (table 2.1A).
Questia, a part of Gale, Cengage Learning. www.questia.com
Book title: Global Environmental Risk.
Contributors: Jeanne X. Kasperson - Editor, Roger Kasperson - Editor.
Publisher: United Nations University Press.
Place of publication: New York.
Publication year: 2001.
Page number: 95.
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