1. Are they Human or Natural?
Are they Cooling or Warming?
Causes of climate change

2. The earths rotation and orbit
As the earth orbits the sun, it wobbles slightly on its axis. These wobbles are named after Milankovitch who discovered them.
In the past the Milankovitch cycles have coincided with ice ages.
http://www.wwnorton.com/college/geo/egeo/flash/18_2.swf
Natural
Human
Cooling
Warming
3. El Nino
Occurs in the Pacific Ocean, where the normal circulation slows, stops and reverses.
This causes the surface of the ocean to become warmer and causes significant changes in the weather patterns around the Pacific and globally
Natural
Human
Cooling
Warming
4. Ice albedo effect
Ice and snow (being white) reflect incoming solar radiation. Albedo means reflectivity.
Where there is a lot of ice it reflects enough energy to reduce global temperature
http://svs.gsfc.nasa.gov/vis/a010000/a010000/a010021/a010021_H264_640x480.mp4
Natural
Human
Cooling
Warming
5. Deforestation of Tropical Rainforests
Tropical rainforest is a natural carbon sink (it absorbs a massive amount of carbon from the atmosphere), reducing CO2 levels.
Evaporation from the Tropical Rainforest is very high and this causes clouds to form which reflect the suns energy
When the rainforest is removed less CO2 is absorbed and less clouds form.
Natural
Human
Cooling
Warming
6. Fossil fuel burning
Burning fossil fuels releases large quantities of CO2 into the atmosphere causing the enhanced greenhouse effect.
Natural
Human
Cooling
Warming
7. Deforestation of boreal (conifer) forest (in Siberia and Northern Canada)
When forest is cleared in the far north it increases the albedo (reflectivity) of the earth because the forest is dark in colour and snow stays longer on the ground
Natural
Human
Cooling
Warming
8. Volcanic activity
Large volcanic eruptions create huge quantities of particles which encircle the earth in the upper atmosphere.
These reflect radiation and shade the earth for up to 5 years.
Natural
Human
Cooling
Warming
9. La Nina
Occurs after El Nino. The Pacific circulation restarts, stronger than usual, this means that the surface waters have less time exposed to the sun, and to warm up.
The ocean surface is cooler.
Natural
Human
Cooling
Warming