AN INTRODUCTION
The earth’s climate is predicted to change because human activities are
altering the chemical composition of the atmosphere through the buildup
of
greenhouse gases—primarily carbon dioxide, methane, and nitrous oxide.
The
heat-trapping property of these gases is undisputed. Although uncertainty
exists
about exactly how earth’s climate responds to these gases, global temperatures
are rising.
This Graph shows the annual amount of CO2 being given off into the atmosphere
by certain sources. The
down arrows represent the taking in of CO2, and the up arrows represent
the giving off of CO2.
The measurement is given in billions of metric tons.
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