Environmental Engineering Reference
In-Depth Information
in its most elemental form. Accelerated by human
interference, it has become the most serious
environmental problem facing some of the
countries of the earth's arid zones. Climatologists,
agronomists, foresters and scientists from a
number of United Nations organizations have
been wrestling with it for nearly forty years, yet
even now it receives less public recognition than
the drought and famine with which it is
associated. Despite this lengthy investigation,
attempts at the prevention and reversal of
desertification have met with only limited success.
In part, this appears to be the result of
misinterpretation of the evidence, and all aspects
of the problem—from identification, through
causes, to response—are currently undergoing
rigorous reassessment. Like most environmental
issues, desertification is not just a physical
problem. It has socio-economic and political
aspects—ranging from the depressed economies
of many Third World nations to the civil strife in
countries like Ethiopia and Somalia—which
complicate the search for appropriate solutions.
Public interest in drought, famine and
desertification will continue to fluctuate.
Heightened concern, followed by increased
financial, nutritional and food aid, may help to
alleviate some of the immediate effects of the
problems, but it is the steady, less volatile interest
of the scientific community which has the
potential to bring about longer-term relief.
have been resolved. There are indications that
lakes and forests are showing some signs of
recovery in the most vulnerable areas of North
America and Europe, although this is still a
matter of some dispute.
Developments such as these have created the
perception that the acid rain problem is being
solved. Interest has declined, and the research
funds available have been diverted to causes—
such as ozone depletion and global warming—
that now appear more relevant. Although acid
rain is arguably a less serious problem than it
once was, it has not been solved. It has changed
in nature and geographical extent, however. In
the developed nations, NO
X
is gradually making
a larger contribution to acidity as levels of SO
2
decline. In less developed areas, from eastern
Europe to China and parts of the southern
hemisphere, the full impact of acid rain may still
be in the future, and the research activities
currently winding down may have to be revived
to deal with it.
Ozone depletion and global warming
Ozone depletion and global warming currently
enjoy a much higher profile than the other
environmental issues, both in the media and in
the scientific community. They are the focus of
major research efforts costing millions of dollars
aimed at deciphering the causes and effects of
the problems so that solutions can be identified.
The intensity of the research effort has ensured
some success, but in many cases the search for
information has done little more than confirm
the complexity of the earth/atmosphere system.
Interest in the topics has been developed and
maintained through a continuing series of high
level international conferences, some of which
concentrate on the technical aspects of the
problems, while others involve policy
development and decision-making. These are
complemented by national and regional
conferences dealing with specific aspects of the
problems.
Progress in the development of the topics has
not been even. Consideration of ozone depletion
Acid rain
The study of acid rain has declined remarkably
since the early 1980s, when it was viewed by
many as the major environmental problem facing
the northern hemisphere. This decline has led one
writer to wonder, 'Whatever happened to acid
rain?' (Pearce 1990). It certainly has not
disappeared, but it is one environmental issue in
which abatement programmes have met with
some success. Sulphur dioxide levels continue to
decline, the rain in many areas is measurably less
acid than it was a decade ago, and the
transboundary disputes which absorbed large
amounts of time, energy and money in the 1980s,
