Environmental Engineering Reference
In-Depth Information
seen that especially for noble metals like gold and platinum, the eco-rucksack is
huge, which means that enormous amounts of residues and wastes are discharged
to the environment in extracting and producing them. The environmental impact
of mineral extraction can thus also be huge; as one example, a nickel mine in New
Caledonia takes nickel from an ore containing only ~ 2 % nickel, which is also
unevenly distributed beneath the ground surface. Obtaining nickel thus requires
destruction of the previous forest ecosystems, in which 95 % of the plants were
endemic species. This ecosystem is destroyed in the mining operations, and soil
washed away from the mine causes severe damage to the ecological system of the
adjoining Coral Sea. Such mining developments thus seriously conflict with the
environment and the people living there. Similar effects are seen around the world
as demand for minerals grows; one of the most recent being the destruction of hun-
dreds of square kilometers of Canadian forest to extract bitumen from the tar sands
underground. With the continued rapid growth in demand for metals and rare earth
elements, the importance of recovering the elements after use and 'urban mining'
thus takes on a greater significance and urgency than ever before.
The Ecological Footprint
represents the amount of biologically productive land
and sea area necessary to supply the resources that a human population consumes,
and to absorb or mitigate the associated waste (Wackernagel and Rees
1995
). It is
expressed by the area (hectare) needed to support a sustainable life for one person,
and in 1995 the average across the world was 1.8 ha/person. If the total area cur-
rently demanded by the global population and its lifestyles is calculated, the sum
now exceeds 150 % of the total surface area of the earth. This means that our world
has already overshot a sustainable level for society. For example, the USA is the
largest, with the average American requiring 9.70 ha to support their lifestyle. In
contrast, the lowest per person is Mozambique with a demand which is just 1/10 of
the average Japanese footprint. It can be easily seen that 5.3 earths are needed if all
the people living in the world attained the affluent lifestyle of the USA.
The relation between eco-footprint and the human development index (HDI) is
shown in Fig.
3.5
for various developing and developed countries. HDI is used by
the United Nations and indicates the average of life expectancy, education and GDP,
which may describe the development level of countries more accurately than GDP
alone. In Fig.
3.5
, there is a general trend to increase the ecological footprint as the
HDI increases. However, there are exceptions and Cuba appears to be a remarkable
country that achieves low eco-footprint and simultaneously a high HDI. I will return
to this towards the end of this chapter.
Factor X
refers to the possibility of reducing the rate of mass-throughput in
society by increasing the efficiency with which society uses resources and energy.
If Factor X = 10, then society needs only 10 % of the current resources to support its
activities which can make a considerable contribution to its sustainability. We can
calculate what might be the conditions for a sustainable world if we make certain
assumptions (Yamamoto
2001
):
A is the consumption of resource/energy per billion people/year for 4.8 billion
in developing countries
B is the consumption of resource/energy per billion people/year for 1.2 billion
in developed countries
