Geoscience Reference
In-Depth Information
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Ye a r
Fig. 7.2
Worldwideaveragewealth(annualincome)perpersonin2011USdollars.Wealthpercapitaisexpressedhere
notasworldgrossdomesticproduct(GDP)inatraditionalsensebutasgrossnationalincome(formerlygross
nationalproduct)perperson.Itincludesincomefrominvestments.Itiscalculatedhereontheexchange-rate
basisasopposedtothepurchasingparitybasis.Thesecaveatsarementionedincaseyoucomeacrossother
globalwealthindicators.ThedatafromthegraphwasdownloadedfromtheWorldBank'swebsiteat
http://data.worldbank.org/indicator/NY.GDP.PCAP.CDinNovember2011.
affluence is reflected in parameters such as household size (number of occupants),
which is one of the key indicators of a populations' environmental impact, although
the relationship is not a linear or a proportional one. The broad reason for this is that a
building or apartment consists of a fixed mass, volume and area so that even if the food
and water and other consumables used by a household of three are approximately half
those of a household of six, the same volume of air and bricks needs to be warmed
with both households, irrespective of the number of people living there. In short,
there is a decrease in energy intensity per person as the number of occupants in a
household increases.
Furthermore, a halving of household size for a fixed population means that the
number of houses required for that population doubles. Take both factors (energy
intensity and number of households) together and it can be seen that a halving
of household size more than doubles the environmental impact. This decrease in
household size is manifest in both less-developed and developed nations, albeit more
markedly in the latter (see Figure 7.3).
Decline in household size is just one aspect of the way affluence generates envir-
onmental impact irrespective of population size. Affluence, among other things, also
affects annual per-capita distance travelled and consumption of material goods, water
and food. In terms of greenhouse impact, goods and services each have an inherent
energy content (energy intensity) associated with their production and delivery. If
this energy comes from fossil fuel then there will be an associated greenhouse cost.
This cost might be met (say by chemically capturing the carbon dioxide emitted from
the power station [see Chapter 8], through planting new woodland, etc.) and the cost
covered by the price of the energy sold. Or, alternatively, this greenhouse cost may
not be met, in which case the greenhouse gas escapes, to warm up the planet. In this
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