Page 14 - Managing Global Warming

8 Managing Global Warming

cycles; cosmic ray effects; and atmospheric aerosols. The first of these, relating to
possible variations in solar radiation, has been investigated by many scientists, and
all agree that this is not the main cause of our present situation [20]. Volcanic activity
on earth has in the past resulted in short-lived climate changes, but experts working in
the field state that this could not possibly be responsible for our present climate change
[21]. The earth’s wobble as it moves around the Sun is another possible culprit for
inducing climate change. However, Lourens and Truter, scientists working in this
area, have stated that from all the evidence, it is most likely that the climate change
that we are currently experiencing is not due to variations of the earth’s orbital move-
ments [22]. Solar activity and cosmic ray bombardment from space is yet another
possible cause of climate change, but experts S. Cohen and G. Stanhill feel that these
effects cannot possibly be responsible for our present global warming [23].
Recent work by Macott et al. has prompted these researchers to write: “The earth’s
climate is complex and responds to multiple forcings, including CO 2 and solar inso-
lation. Both of those have changed very slowly over the past 11,000 years. But in the
last 100 years, the increase in CO 2 through increased emissions from human activities
has been significant. It is the only variable that can best explain the rapid increase in
global temperatures” [24].
Superimposed on the scenario of global warming is the effect of global dimming
[20]. This effect was especially noticeable between the 1950s and 1980s when it was
found that the sun’s energy reaching places on the surface of the earth were less than in
previous years—the reduction being of the order of a few percent. It was attributed to
aerosol formation and particulates in the atmosphere resulting from the burning of
coal and other hydrocarbons [25]. These particles were reflecting the sun’s rays back
into space, resulting in a dimming of the solar radiation. This effect does partially
compensate for global warming. This is an important issue as the presence of partic-
ulate matter is responsible for major smog problems in some parts of the world,
especially in China. Furthermore, particulates in the atmosphere are also related to
illnesses suffered by asthmatics and other people with lung problems. These two
issues have precipitated a drive to reduce particulates in the air by introducing precip-
itators at coal-burning power stations and replacing coal burning with renewable
forms of energy. Reducing particulates in the atmosphere would reduce the global
cooling effect and as a result could trigger a major increase in global warming unless
there is a serious commitment to replacing fossil fuel burning processes with nonfossil
fuel forms of energy.
In this chapter, the major greenhouse gas discussed has been CO 2 , but there are
other gases that are far more effective greenhouse gases. These include chlorofluoro-
carbons (CFCs) and nitrogen oxide (NOx) compounds. Fortunately, these are in very
low concentrations in the air. These have been discussed by Tuckett [13]. Further-
more, a recent study of the effects of CFCs on global warming by Quing-Bin Lu
of the University of Waterloo, has confirmed that these compounds are serious
contenders for the most potent of greenhouse gases. It is not only their potency that
is an issue but also their long lifetime in the atmosphere (see Table 1.3). In spite of
their present low concentrations, they should be banned from production as their
build-up in the atmosphere could be very damaging to future generations [26].