Video Transcript
Which of the following greenhouse
gases, which accounts for approximately two-thirds of the total greenhouse gases
produced, is generated largely through the burning of fossil fuels? (A) Methane, (B) carbon monoxide,
(C) water vapor, (D) nitrogen, (E) carbon dioxide.
A greenhouse gas is a gas found in
Earth’s atmosphere that absorbs infrared radiation, causing the atmosphere to heat
up. When the Earth is warmed by the
Sun, short-wavelength radiation, such as visible light and ultraviolet, are
absorbed. The warmed Earth then emits
infrared radiation of a longer wavelength, most of which passes into space. Some of this longer-wavelength
radiation is absorbed by gases in the Earth’s atmosphere. This has a heating effect on the
atmosphere.
Approximately 78 percent of the
Earth’s atmosphere is nitrogen gas. Nitrogen does not absorb infrared
radiation, and it is not a greenhouse gas. Since nitrogen is not a greenhouse
gas, it cannot be the correct answer to this question.
The greenhouse gases methane,
carbon monoxide, water vapor, and carbon dioxide are found in Earth’s atmosphere in
varying amounts. Of all the greenhouse gases
produced, carbon dioxide is present in the largest amount. Man-made carbon dioxide emissions
primarily originate from the burning of fossil fuels, such as coal and oil
products. Carbon dioxide could be the correct
answer to this question.
Methane emissions make up a smaller
amount of the total greenhouse gases produced. It can escape from oil wells and
where decaying matter lies underground. Methane is a fossil-fuel product,
and when it is burnt, carbon dioxide gas is produced. Although methane is a greenhouse
gas, it is not generated through the burning of fossil fuels. Methane is not the correct
answer.
Other greenhouse gases exist in
Earth’s atmosphere in very small amounts. When fossil fuels are burnt in
insufficient oxygen, small amounts of carbon monoxide may also be produced. Since the level of carbon monoxide
in Earth’s atmosphere is very small compared to the level of carbon dioxide, carbon
monoxide is not the correct answer.
Water vapor is generated naturally
through the evaporation of water from the seas and oceans. Although small amounts are formed
from the burning of fossil fuels, water vapor is not the correct answer.
The correct answer to “Which of the
following greenhouse gases accounts for two-thirds of the total greenhouse gases
produced that is generated largely through the burning of fossil fuels?” is answer
choice (E), carbon dioxide.
