Environmental Engineering Reference
In-Depth Information
The Nasty Gases
Many of the gases humans add to the atmosphere, as well as the soot
spewing from our fossil fuel-consuming inventions, are contributing to
global warming. Thirty-two percent of the greenhouse gases are gener-
ated from transportation, 43 percent from electricity production, and 25
percent from other sources.
Carbon Dioxide
Since the Industrial Revolution, the global atmospheric concentration of
carbon dioxide has increased by 36 percent and is now 388 parts per
million (ppm), the highest concentration in the past 800,000 years. It is
rising at about 2 ppm per year. About 6.725 billion tons of carbon
dioxide were emitted in the United States in 2007, an increase of 20
percent since 1990 and 2.5 percent since 2000.
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Total world emissions
of carbon dioxide are over 30 billion tons a year at present.
Excluding water vapor, carbon dioxide is the major gaseous contribu-
tor to global warming (40 percent), not only because of its dominance
volumetrically, but also because of its lifetime in the atmosphere. A large
number of sources, sinks, and feedback loops are involved in the cycling
of carbon dioxide, so the lifetime of the gas in the atmosphere cannot be
calculated accurately. However, experts agree that it will require at least
hundreds, and probably thousands, of years for all of the carbon dioxide
humans have put in the atmosphere to be removed by natural processes.
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Because of slow removal processes, atmospheric carbon dioxide will con-
tinue to increase in the long term even if its emission is substantially
reduced from today's levels. We have created a monster that untold
numbers of generations will have to contend with during their lifetimes.
There is no question that Western industrialized nations are respon-
sible for most of the carbon dioxide that has been added to the atmo-
sphere. However, on a volume basis, developing countries, particularly
China, are racing to catch up. China's annual energy-related carbon
dioxide emissions surpassed those of the United States in 2006, years
ahead of published international and Chinese forecasts. But the size of
China's enormous population virtually guarantees the country will never
catch up to the United States on a per capita basis.
Almost all (94 percent) of the carbon dioxide humans spew into the
atmosphere comes from the burning of fossil fuels: coal, oil, and natural
gas.
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(This has recently been disputed. The World Bank estimates that
when the entire life cycle and supply chain of the livestock industry is
