Page 36 - Alternative Energy Systems in Building Design

INDUSTRIAL SOURCES OF ATMOSPHERIC POLLUTION 13

LAND USE

Prior to the widespread use of fossil fuels, humanity’s largest effect on local climate
likely resulted from changes to the environment. For example, human activities change the
amount of water going into and out of a given location. They also change the local
ecology by influencing ground cover and altering the amount of sunlight that is absorbed.
Historical evidence suggests that the climates of Greece and other Mediterranean
countries were permanently changed between 700 BC and 1 AD because of widespread
deforestation (the wood was used for shipbuilding and construction). This finding is
supported by the archeologic discovery of a species of tree that was used for ship-
building in the ancient world but which can no longer be found in the area.
There are also hypotheses that suggest that the rise of agriculture and the accompa-
nying deforestation led to increases in CO and methane gases during the period
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5000–8000 years ago. The increases in CO may have been responsible for delaying
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the onset of a more severe glacial period (Fig. 1.8).
In 2007 it was found that the average temperature has risen about 2°F over the past
50 years, with a much larger increase in urban areas. This change was attributed mainly
to extensive human development of the landscape.

LIVESTOCK

According to a 2006 United Nations report, livestock is responsible for 18 percent of
the world’s greenhouse gas emissions, as measured in CO equivalents. This includes
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land deforestation in order to create grazing land. In the Amazon Basin, 70 percent of
deforestation has been to make way for grazing land. In addition to CO emissions,
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Figure 1.8 The main greenhouse gases. Courtesy of United Nations Environmental Program/GRID-Arendal.