1. Introduction Is the world getting warmer?
If so, are the actions of mankind to blame for earth’s temperature increases?
What can/should be done about these issues?
In examining global warming, we will be looking at questions such as 
Is the world getting warmer? 
If so, are the actions of mankind to blame for earth’s temperature increases? 
What can or should be done about global warming? 
Are the potential resolutions to global warming worth the cost to implement them? 

2. History of Earth’s Climate
Earth formed ~4.6 billion years ago
Originally very hot
Sun’s energy output only 70% of present
Liquid water present ~4.3 billion years
This is a big picture examination of the earth’s climate 
The Earth was formed around 4.6 billion years ago 
And was originally very hot 
However, the Sun’s energy output was only 70% of what it is presently 
Liquid water was present on the surface around 4.3 billion years ago

3. History of Earth’s Climate
Life appeared ~3.8 billion years ago
Photosynthesis began billion years ago
Produced oxygen and removed carbon dioxide and methane (greenhouse gases)
Earth went through periods of cooling (“Snowball Earth”) and warming
Earth began cycles of glacial and interglacial periods ~3 million years ago
The first life forms appeared ~3.8 billion years ago 
Photosynthesis began billion years ago, 
which produced oxygen and removed carbon dioxide and methane, which are greenhouse gases, from the atmosphere 
As a result, the Earth went through periods of cooling, commonly referred to as “Snowball Earth” and subsequent warming 
Earth began its current cycles of glacial and interglacial periods around 3 million years ago 

4. Earth’s Temperature Solar Energy Solar Energy Sun
The temperature of the earth is directly related to the energy input from the Sun.  Some of the Sun’s energy is reflected by clouds.  Other is reflected by ice. The remainder is absorbed by the earth. 

5. Earth’s Temperature Solar Energy Radiation Cooling Sun
 If amount of solar energy absorbed by the earth is equal to the amount radiated back into space, the earth remains at a constant temperature. 

6. Solar Energy Earth’s Temperature Sun Radiation Cooling
 However, if the amount of solar energy is greater than the amount radiated, then the earth heats up. 

7. Radiation Cooling Earth’s Temperature Sun Solar Energy
 If the amount of solar energy is less than the amount radiated, then the earth cools down. 

8. Sun
Greenhouse Effect
To a certain degree, the earth acts like a greenhouse.  Energy from the Sun penetrates the glass of a greenhouse and warms the air and objects within the greenhouse. The same glass slows the heat from escaping, resulting in much higher temperatures within the greenhouse than outside it. 

9. Earth’s Atmospheric Gases
Nitrogen (N2)
Non- Greenhouse
Gases
99%
Oxygen (O2)
Water (H2O)
Greenhouse
Gases 1%
Likewise, the earth’s atmospheric gases affect the ability of the earth to radiate the Sun’s energy back into space.  Nitrogen and  Oxygen  make up 99% of the earth’s atmospheric gases  and are non-greenhouse gases.  Water,  Carbon Dioxide,  and Methane  make up 1% of the earth’s atmosphere,  but are greenhouse gases, since they cause the earth to retain heat. 
Carbon Dioxide (CO2)
Methane (CH4)