2. Human Causes of Climate Change

3. Greenhouse Effect
The greenhouse effect is what keeps the Earth warm by trapping heat in the atmosphere.
This keeps the Earth warmer than direct heating by the Sun.

4. Earth The Greenhouse Effect Atmosphere Sun
Greenhouse gases in the atmosphere prevent some of that energy from leaving back into space, by sending some of the Sun’s energy back to earth.
Sun
The Sun’s energy reaches the Earth’s surface, and some of it warms the ground.
The rest bounces back and enters the atmosphere.
Atmosphere
Earth

5. History of the Greenhouse Effect
During the Jurassic Period, the Earth’s global temperature was much higher than it is today.
Carbon dioxide levels were five times higher than today!

6. However…
Historically it has taken Earth about 5,000 years to warm by 5°C.
From 1850 to 2015, the Earth’s average temperature has already increased by 1°C

7. How are Humans Affecting the Greenhouse Effect?
Humans are increasing the amount of greenhouse gases in the atmosphere.
This makes the greenhouse effect stronger, which means it traps more of the suns energy, causing the global temperature of the Earth to increase.

8. There are five main greenhouse gases:
Carbon dioxide
Methane
Surface ozone (smog)
Nitrous oxide and fluorinated gases
Water vapour
Beijing 2015

9. Why is carbon dioxide (CO2) such a big deal?
Most emitted greenhouse gas
CO2 emission is increased by burning fossil fuels
CO2 removal is decreased by deforestation
It will stay in the atmosphere for approximately 200 years on average, but can last for up to 1000 years.

10. Media and Images

11. Front of the Classroom 1 2 1 2 5 3 5 3 4 4