Vocabulary Preview
Match each word or phrase with the correct definition.
1. consequence
a. a meeting between heads
of governments or officials
2. delegate
b. unlikely; not very possible
3. improbable
c. something given off or released into the air
4. emission
d. a person acting as a representative
5. protocol
e. a result
6. summit
f. a first draft from which a treaty is prepared
Pre-Reading Questions
Think about the following questions.
1. What produces greenhouse gases?
2. Why is the greenhouse effect bad?
3. Is the yearly rate of air pollution in your country now better or
worse than the rate in 1990?
A Plan to Curb
Greenhouse Gases
E n v i ro n m e n t a l I s s u e s 2
U N
I
T
5
60
A Plan to Curb Greenhouse Gases
5
10
15
20
25
A
s sunlight shines on the Earth, solar radiation is absorbed and then
radiated back into space as thermal radiation (heat). However, some
of this heat is trapped by gases in the atmosphere. The trapped heat
increases the temperature of the Earth’s surface and atmosphere. The process is
similar to the way a greenhouse is kept warm. The Earth’s
natural levels of water
vapor and other gases produce this greenhouse effect, making life on Earth
possible. However, some scientists are now predicting that higher levels of
certain greenhouse gases are causing temperatures to rise beyond natural limits.
Since the beginning of the industrial age, carbon dioxide (CO
2
) has been
building up in the Earth’s atmosphere
as a result of the burning of fossil fuels
(coal, oil, natural gas). CO
2
is considered the major cause of global warming on
Earth. Other natural greenhouse gases include water vapor, methane (CH
4
),
nitrous oxide (N
2
O), and ozone (O
3
). Additionally, several man-made gases are
also thought to contribute
to the greenhouse effect, namely chlorofluorocarbons
(CFCs), hydrochlorofluorocarbons (HCFCs), and sulfur hexafluoride (SF
6
).
Researchers have estimated that the atmospheric
concentration of CO
2
has
increased by at least 30 percent since the 1800s. Industrial processes have also led
to a 145 percent increase in CH
4
, and 15
percent increase in N
2
O in the atmosphere.
The buildup of these gases is believed to be the major cause of higher than
normal average global temperatures in recent
years. Consequences of such global warming
could include higher sea levels,
the spread of
deserts in areas around the Earth’s
equator, and
the drying up of fresh water sources.
In December 1997, at a United Nations
summit on global warming in Kyoto, Japan,
2
radiate --- to send out like light
10
fossil fuel --- fuel made from fossil remains of plants and animals
16
concentration --- the amount of a specific
thing found in an area
23
equator --- the imaginary line around the Earth at O(zero)º latitude
