Causes of Climatic Variability
- Solar output: An increase in solar output by 0.3% when compared to 1650–1700 A.D. data.
• Orbital variation:
1. Earth orbit varies form almost a complete circle to marked ellipse (Eccentricity).
2. Wobble of earth’s axis (Precession of equinox)
3. Tilt of the earth’s axis of rotation relative to the plane of the orbit varies between 21.8º and 24.4º.
• Changes in the atmospheric composition-change in the green house gases especially CO2
• Land surface changes particularly the afforestation and deforestation
• The internal dynamics of southern oscillation–changes in the sea surface temperature in western Tropical Pacific (El-Nino/La-Nina) coupled with Southern Oscillation Index, the Tahiti minus Darwin normalized pressure index leading to the ENSO phenomena
• Anthropogenic causes of climate variation in green house gases and aerosols.