Geoscience Reference
In-Depth Information
combustion engine (together with inexpensive steel, aluminium, explosives, syn-
thetic fertilizers and electronic components), marked a technical watershed in recent
economic history.
1.4.7 Energy and Environment
Among the different sources of energy, only the exploitation of wind, water and
direct solar energy do not modify the environment since they do not cause a change
in the molecular or atomic composition of matter. Whenever, by contrast, either the
molecular or nuclear composition of matter is modi
ed, even by the mere digestion
of food, some change is introduced in the environment and some waste is produced.
It is known that some environmental effects were produced by humans in past
civilisations and that deforestation was not unknown in ancient economies. Lead in
the atmosphere was notable in Roman antiquity due to melting metals, as the ice of
Antarctica and Greenland has shown.
19
In any case, much heavier were the con-
sequences of the environment on energy consumption by the humans than of
human energy consumption on the environment. Both annual changes in temper-
ature and rain, and long-term climatic cycles resulted in changes in the available
energy, and subsequently in the level of the economic activity.
The 45
50-fold growth of energy consumption on the World scale, in the last
200 years, and the higher emissions by fossil fuels resulted in a dramatic rise in the
level of gases in the atmosphere. Carbon dioxide (CO
2
), water vapour, methane,
nitrous oxide, and a few other gases are de
-
ned greenhouse gases. Their presence in
the air has risen fast since the introduction and ever increasing use of coal and the
other fossil carriers. Remarkable differences, however, exist among them: natural
gas is much less polluting than oil, which is less polluting than coal. According to
most paleo-climatologists the rise in temperature during the last century can be
explained only as a consequence of the modern energy system and emissions of
carbon dioxide into the atmosphere. Although the declining energy intensity from
the 1990s results in a relatively lower impact of energy consumption on the
environment, the fast rising energy consumption in absolute terms more than
counterbalances the positive effect. On one hand, CO
2
emissions tend to decrease in
relation with per capita GDP, since in rich countries energy intensity diminishes
(Table
1.8
). On the other hand, however, as a consequence of the high production
per capita, per capita emissions in absolute values are much higher in rich than in
poor countries. On the World scale, during the
rst decade of the third millennium,
emissions averaged 4.5 tons per capita per year.
CO
2
emissions increased from 18,500 million of metric tons in 1980 to almost
30,000 million in 2006: a 60 % rise in less than 30 years. On the other hand,
attempts at
the reduction of CO
2
emissions in order
to stabilize or reduce
19
As stated by Rossignol and Durost (
2007
).
