The atmosphere and carbon dioxide

In a nutshell

The Earth's atmosphere is made up of different gases, including carbon dioxide. Atmospheric carbon dioxide is increasing due to human activity. This contributes to an increase in the greenhouse gas effect, global warming and climate change.

Atmosphere

Atmosphere is the layer of gases that surrounds a planet. The two most abundant gases in the Earth's atmosphere are nitrogen and oxygen. Other gases present in the Earth's atmosphere include carbon dioxide, water vapour and the noble gases.

Note: Noble gases are the elements in Group $0$ of the periodic table.

ATMOSPHERIC GAS	PERCENTAGE ABUNDANCE ( $\%$ )
Nitrogen	$78$
Oxygen	$21$
Other gases	$1$

Climate change

Climate change is the global, long-term changes in weather patterns and temperature. A key aspect of climate change is global warming. Global warming refers to an increase the Earth's average temperature

The greenhouse gas effect

Greenhouse gases (atmospheric gases that absorb infrared radiation) prevent thermal energy from escaping back to space, which causes the Earth's surface to become warmer. The greenhouse gas effect is required, as otherwise all heat would be re-emitted back to space and the Earth would be too cold for most species to survive. However, human activity has led to an unusual increase in the greenhouse gas effect, which has led to global warming and climate change.

Science; Earth and atmosphere; KS3 Year 7; The atmosphere and carbon dioxide

Key steps

1.	Electromagnetic radiation is emitted by the sun, reaching the Earth's atmosphere.
2.	Most of the electromagnetic radiation is re-emitted back into space.
3.	Some heat, in the form of infrared radiation, is absorbed by greenhouse gases in the Earth's atmosphere; this is the greenhouse gas effect.

Carbon dioxide

Carbon dioxide is an example of a greenhouse gas. Carbon dioxide ( $CO_2$ ) is a molecule consisting of one carbon atom bonded to two oxygen atoms. Human activity has led to an unusually high increase in atmospheric levels of carbon dioxide since $1750$ . This has increased the greenhouse gas effect, causing global warming and climate change

Effects of global warming

Global warming has many negative impacts on the environment.

Examples

Rising sea levels
Increase in extreme weather events, such as floods
Loss of habitats