Vol. 1(2) SEP 2011 - SAVAP International

Academic Research International
ISSN: 2223-9553
Volume 1, Issue 2, September 2011
Percentage increase in emissions
low income lower-middle income upper-middle income high income
1.58 1.97 1.42 0.83
In other words, in lower-middle income countries the elasticity of emissions with respect to
population is nearly two, while in high income countries it is less than one.
Since developing countries have relatively low per capita incomes compared with
developed countries,we see that the impact of population growth on emissions is bigger
in developing than in developed countries. This conclusion with carbon dioxide stands
somewhat in contrast with the conclusion of York et al (2003b) for ecological footprints,
mentioned above. And we note that most future population growth will be in developing
countries.
Shi's overall conclusion is that population growth has had a severe adverse effect
globally on emissions over the last two decades.
Shi went on to prepare forecasts of global emissions up to 2025, using the United Nations
low, medium and high population growth variant projections for population data. The 1990
global population was 5.266 billion and total carbon emissions were 6 gigatons. With the low
variant projection, global CO 2 emissions will reach about 12.4 Gt of carbon. With the high
variant, the figure is 14.2 Gt of carbon. The implications for global warming are terrible.
Cole and Neumayer (2004) made a study of the relationship of demographic factors to CO 2
and SO 2 emissions, : for CO 2 , they worked with data from 86 countries over a period of 24
years (1975-1998); with SO 2 , the data came from 54 countries and twenty years (1971 -
1990). There were important differences between the results for the two pollutants.
With CO 2 , population increases were matched by proportional increases in emissions: the
elasticity of emissions with respect to population were approximately unity over the entire
range of country population sizes. The authors comment that their results of unit elasticity
with CO 2 confirm the results of Dietz et al (1997) and York et al (2003a). They also question
the validity of Shi's much higher elasticity estimates on statistical methodology grounds.
The authors also found, first that a higher urbanization rate increased emissions, a result
consistent with the findings of York et al (2003a) we mentioned earlier; second that lower
average household size increased emissions.
With SO 2 , results were different: there was a U-shaped relationship with population.
Population - emission elasticity was negative for very small populations but rose rapidly as
population increased. The turning point was about 5.4 million people. So “population
generates an increase in emissions for all populations over 5.4 million”. Now only a quarter
of all countries in the sample have a population below this threshold, so for most countries,
an increase in population causes an increase in emissions. Further, urbanization and
household size did not make significant contributions to change in SO 2 emissions.
What do the authors think are the reasons for the differences between the two pollutants
"The most likely explanation is that SO 2 and CO 2 emissions differ in their sources. CO 2
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