Plants Theory (recent):
- Given by University research team
- Global cooling was caused by reduction of carbon in the atmosphere due to the first appearance of plants (photosynthesis)
- Less greenhouse gas (carbon) to prevent escape of infrared radiation which leads to cooler temperatures (less heat trapped)
- Plants (ex. moss) extract calcium, magnesium, phosphorus and iron which weathers the land
- Weathering triggers more carbonate rocks and carbon burial bodies of water
Continental Drift Theory:
- Given by A. Wegner in 1922
- Continents move on the surface of the globe
- Movements of the poles
- Supports developments of ice sheets
Astronomic theories
1.) A change in the eccentricity of the earth’s orbit
- Earth’s orbit is altered (made more/less eccentric) by gravity of other planets or special bodies
- Causes temperature on earth to be colder or warmer (further or closer from the sun)
- Alters the distribution of solar radiation
- Cold can contribute to positive feedback loop of ice (Aledo)
2.) The earth’s tilt changes
- Earth’s tilt causes more extreme temperatures in summer and winter
- As tilt gets larger, so do the extremities in temperature
- Tilt changes about every 40,000 years
3.) The earth’s wobble (precession)
- Earth has a precession cycle of about 23,000 years
- Affects the climate temperatures in various parts of the world as the wobble changes where the axis is pointing (changes where there’s summer and winter)
- When earth is in a position where the poles get even colder temperatures, it makes the entire earth colder (possible cause of ice ages)
