Theories to account for climate change. Each theory is helpful in explaining some of the historical record, usually focusing on different time scales. A. Plate tectonics - As we will soon learn, the continents are not permanently anchored in place, but move across the lithosphere. Places like Antarctica, which today straddles the south pole, were once equatorial latitudes. About 100,000 yr cycle.
Helps account for pattern of glacial advances and retreats.
The axis wobbles on about 26,000 yr cycle. Changes the seasonal timing of perihelion and aphelion. C. Solar variability . Changes in amount of radiation emitted by the sun. We are just learning about this possibility.