S e c o n d e d I t I o n 1 Reading for the Real World 1

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

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