Video Transcript
What would happen if all of the
greenhouse gases were removed from the atmosphere? (A) The average global temperature
would become very hot. (B) The average global temperature
would return to the temperature it was around 1750. (C) The average global temperature
would stay the same. (D) The average global temperature
would become very cold.
Some of the gases found in Earth’s
atmosphere, both naturally and through human activity, are greenhouse gases. Some examples of greenhouse gases
include carbon dioxide, water vapor, methane, and nitrogen oxides. Greenhouse gases absorb and emit
infrared or IR radiation emitted by the Earth’s surface, clouds, and the
atmosphere. This contributes to the greenhouse
effect.
The greenhouse effect is the
process through which gases in the Earth’s troposphere trap the Sun’s heat in the
form of IR radiation. Let’s take a closer look at this
process. As ultraviolet or UV radiation and
visible light from the Sun move through the atmosphere, some of the radiation is
reflected back into space by the atmosphere and the Earth’s surface. In addition, some of the
ultraviolet radiation is absorbed by the ozone layer in the stratosphere. Some of the ultraviolet radiation
and visible light that reach the Earth’s surface are absorbed by the Earth. Some of the absorbed radiation is
emitted as infrared or IR radiation. Most of this IR radiation is
absorbed by greenhouse gases in the troposphere.
The energy is then released from
the gas molecules as thermal energy that warms the Earth. The greenhouse effect is a natural
process that is essential for maintaining a temperature in which life on Earth can
be sustained. But a change in the amount of
greenhouse gases in the atmosphere can create an imbalance. An increase in the amount of
greenhouse gases in the atmosphere results in more heat being trapped, which in turn
can cause global warming, an increase in the average global temperature. But if the greenhouse gases were
removed from the atmosphere, the infrared radiation emitted from the Earth’s surface
would not be trapped. The thermal energy would be lost in
space, and the average global temperature would be considerably colder.
So, if all of the greenhouse gases
were removed from the atmosphere, the average global temperature would become very
cold, answer choice (D).