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Chapter Five: Coal and the Environment
A Warmer Earth
Global warming is predicted not only to make
the Earth’s air, land, and water hotter, but
also to change patterns of weather, create
more storms and other extreme events, bring
droughts and floods to new regions, and
warm the oceans, which will kill corals and
marine life. It will melt glaciers and ice caps
to raise the sea level and flood vast low-lying
areas. And there are probably many more, as
yet unknown, effects of global warming.
Greenhouse Gas
Almost any kind of burning produces carbon dioxide. It is called a greenhouse gas
because, in the atmosphere, it helps to trap and hold heat—much like the panes of
glass in a greenhouse. Along with other greenhouse gases, such as methane, carbon
dioxide is causing the surface temperature of the Earth to rise, a phenomenon
termed
global warming.
Nearly all scientists now agree that global warming is here,
that it is increasing, that it is caused by human activities—chiefly, burning fossil
fuels.
In North America, carbon dioxide accounts for about four-fifths of all greenhouse
gas emissions. About one-third of this carbon dioxide comes from electricity
generation, and coal creates around two-fifths of these emissions. Taking into account
other coal uses, coal is responsible for broadly 30 to 35 percent of US greenhouse
gas emissions. (Similar calculations show that petroleum oil is the source of up to 40
percent of US greenhouse gas emissions.)
Methane constitutes around one-tenth of North America’s greenhouse gas
emissions. Methane is very powerful—it is more than 20 times more effective at
trapping heat than carbon dioxide over a time span of 100 years. However, methane
does not last in the atmosphere as long as carbon dioxide does. So its greenhouse
effects are bigger over a short period, while carbon dioxide’s are not as big but last
longer, since it persists for 100 to 200 years. Low-level methane seeping from surface