Unit 4 Climate change

Unit 4:  Climate Change & Sustainability Changing weather patterns Natural vs. Anthropogenic influence Socioeconomic factors Feedback loops Humans Impact Sustainability

• How does the Sun Warm the Earth?

Radiation !!!

Solar radiation warms Earth and its atmosphere.

The balance between the inflow  and outflow of radiation results in  a relatively constant temperature

Like all warm objects, Earth gives off  radiation and cools. 

Infrared Radiation cools Earth​.

Solar Radiation warms Earth 

Electromagnetic radiation is a type of solar radiation that heats the earth. This includes:
· ultraviolet light (short wavelength) 

· visible light (medium wavelength)  

· infrared light (long wavelength) 

Earth's Atmosphere & Temperature

The earth would be much cooler if not for its atmosphere. Certain gases in the atmosphere, greenhouse gases, absorb infrared radiation and slow its escape into space. The result is that the temperature of Earth is warmer than it would be if there were no atmosphere. Without its atmosphere, Earth's oceans would freeze and life as we know it would be difficult.

Greenhouse gases keep Earth warmer and support life.

Earth's Atmosphere

Earth's atmosphere is mostly composed:
Nitrogen (N2), Oxygen (O2) and Argon (Ar).
These 3 gases make up 99.96% of the Earth's atmosphere.

But, infrared light passes right through those; they don't help keep Earth warm.

The trace gases that comprise the remaining 0.04% of the atmosphere, along with water vapor, are what moderate Earth's temperature.

These are called greenhouse gases. CO2 comprises 93% of those trace gases.

A Warm Planet

The predominant gases in the atmosphere don't warm Earth since  they don't absorb infrared radiation.

Earth is kept warm by these greenhouse gases: 

· Water Vapor (H₂O) 

· Carbon Dioxide (CO₂) 

· Methane (CH₄) 

· Nitrous Oxide (N₂O)

The Greenhouse Effect 

Water vapor (H₂O), carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) absorb the infrared energy that the Earth gives off.
These gases are warmed, causing atmospheric warming. 

The warm gas molecules in the atmosphere radiate heat in all  directions, including back to Earth, helping to keep it warm.

​Greenhouse Effect

​The Greenhouse Effect is due to the absorption of infrared  radiation from Earth by greenhouse gases in the atmosphere and  its radiation of this heat back to earth. 

Too little greenhouse gas in the atmosphere: Earth cools off.
Too much greenhouse gas in the atmosphere: Earth warms up. 

​A Warming Earth 

Greenhouse gases are crucial to human life on Earth.
Without them, Earth would be far cooler than we would like.
The problem we are facing now is having too much of them.

Multiple Choice

The gases responsible for the Greenhouse Effect include all of these but: ____

• oxygen

• methane

• carbon dioxide

• water vapor

Multiple Choice

Earth is kept warm by all of these except ____.

• argon

• carbon dioxide

• methane

• nitrous oxide

Multiple Select

Earth's atmosphere is composed of which gases (check all that apply): _____

• nitrogen

• oxygen

• argon

• methane

Multiple Choice

The earth is warmed by: ____

• infrared radiation

• visible light

• ultraviolet radiation

• All the above

Multiple Choice

The earth is cooled by _____

• conduction

• convection

• infrared radiation

• ultraviolet radiation

Multiple Choice

True of False. Greenhouses gases are essential to life on Earth.

• True

• False

Multiple Choice

True or False: Too much Greenhouses gases is a problem

• True

• False