Global warming is the slight but steady increase
in the earth’s average temperature. It is natural and
has happened before in the earth’s history. But recently
global temperatures have become the highest ever recorded,
causing some scientists to believe that the increase in greenhouse
gasses, due to human activity, is affecting the earth’s
Greenhouse gasses, which include water vapor,
nitrous oxides, carbon dioxide, methane, and chlorofluorocarbons
(CFCs), can be beneficial; they trap solar heat close to the
earth’s surface, which keeps the earth warm. The concern
among some scientists is that an increase in the amount of
greenhouse gasses in the atmosphere will lead to an overheating
of the earth. The earth’s surface temperature is predicted
to rise between two to seven degrees Fahrenheit in the next
century, which may not sound like much, but it is warmer than
the earth has been in the last 10,000 years. Its average temperature
has risen by about one degree in the past century, with much
accelerated warming during the past two decades. This warming
trend, according to these scientists, will also cause changes
in precipitation, sea levels, wildlife habitat, and many other
environmental factors. It has been predicted that one third
of the world’s forests
(both its flora and fauna) will be significantly affected
by global warming.
Greenhouse gasses are increasing due to human
activities. The amount of carbon dioxide in the atmosphere
has increased due to the fossil fuels that are burned for
factories, transportation, heating, and electricity. Since
the Industrial Revolution, carbon dioxide in the atmosphere
has increased by more than 30%.
The United States alone accounts for 23% of all
carbon dioxide emissions caused by human activity. Methane
has increased 151% due to agriculture
and the use of fossil fuels. The use of aerosol propellants
and refrigerants has caused an increase in the amount of CFCs
in the atmosphere as well. Ozone holes, which are thin spots
in the layer that protect the earth from radiation, are also
attributed to increases in CFCs. Nitrous oxides in the atmosphere
have increased 17% since the Industrial Revolution and are
also a major cause of acid rain.
Global warming isn’t just an issue for
icebergs and shorelines—it affects Indiana as well.
The average temperature in Bloomington has increased 1.8°
F during the last 100 years, and precipitation has increased
10%. Gary, Indiana, has been classified as having severe ozone
and global warming problems due to extensive industrial
pollution. These issues have a major effect on agriculture,
which significantly influences the state’s economy.
A 10% decrease in global crop yields would cause an extreme
increase in world hunger and major changes in global economy.
Indiana Dept. of Environmental Management.
"Global and Regional Air Quality." State of
the Environment Report 2002. 28 Oct. 2002. <http://www.in.gov/idem/
G. Tyler, Jr. Environmental Science: Working with the
Earth. 8th ed. Pacific Grove, CA: Brooks/Cole, 2001.