Human Causes of Climate Change:
Greenhouse effect:
● Greenhouse effect = naturally occurring phenomenon tha t keeps the Earth warm enough to sustain life
○ Without greenhouse effect, Earth would be 33°C colder → life wouldn’t exist
○ Process:
1. Sun’s infrared rays enter Earth’s atmosphere
2. Heat is reflected from Earth’s surface
3. Natural layer of greenhouse gases allow some heat to reflect out of Earth’s atmosphere
4. Some of Earth’s infrared heat is trapped in the atmosphere → keeps Earth warm
● Enhanced greenhouse effect = the warming of Earth’s atmosphere due to human activities
○ Increases the layer of greenhouse gases
○ Less heat escapes from Earth’s atmosphere – more is trapped by the thicker layer of gases
○ Earth warms up even more → global warming
● Greenhouse gases consist of:
○ 77% CO 2
○ 14% CH 4
○ 8% NO 2
○ 1% CFC
■ CO 2 makes up majority of the greenhouse gases
● Each molecule of CH 4 is 25 times the global warming potential compared to CO 2
● Each molecule of NO 2 is 125 times the global warming potential compared to CO 2
Human activities contributing to global warming/climate change:
● Natural causes cannot count for increases in temperature since the 1970s
● Human activities have now caused an increase in greenhouse gases and so global warming
● Increasing CO 2 levels have been closely linked to rising global temperatures
○ Humans generate more than 130 times the volume of CO 2 than volcanoes
⇒ Different human activities that increase greenhouse gases:
