Developing Pressure Indicators for Europe
Edited by Anil Markandya and Nick Dale
Chapter 24: Human pressure on environmental systems: the need for change
24. Human pressure on environmental systems: the need for change A. Renzoni 1. NATURAL SYSTEMS AND HUMAN PRESSURE Human population density has, for the ﬁrst time, reached an average density of around ten inhabitants/km2 for the total surface of the earth, or 100 inhabitants/ km2 for total usable land. Wastes and over-exploitation of natural resources are now generating dramatic new problems for present and future generations. The use of large quantities of fossil fuels is, at present, one of the main causes of environmental degradation at both local and global level. Atmospheric chemistry is changing with consequences for the earth’s temperature. The deposition of nitrogen and sulphur oxides originating from combustion processes has caused acidiﬁcation of soils and vulnerable freshwater systems (Scorer, 1994). Even non-toxic substances derived from concentrated human activities can have harmful environmental impacts. For example, the excess of nutrients and non-toxic organic matter discharged into the sea modiﬁes biological (especially microbiological) community composition, reducing species abundance and diversity, and transforming coastal waters into a malodorous gelatinous soup. The Northern Adriatic Sea has increasingly frequent and intense proliferations of mucilages. Past use of recalcitrant chemicals in agriculture and in vector control operations is generating worldwide contamination (without damage to biological systems) and inadvertent, and still little known, pollution (with damage to biological systems). When toxic substances are released into natural systems, they move from release points, in the case of the so-called point-sources such as chimneys and sewage outfalls, or areas, in the case of pesticide...
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