One Hypothesis in Glaciation Cycles of the Earth: (II) A Cause of Appearance of Oscillatory Climate in the Pleistocene

Abstract

With use of a simple climate model, we discuss analytically the cause of appearance of oscillatory climate state on the earth. Introducing a geographical parameter into the climate model, we investigate a relationship between emergence of oscillatory climate and continental drift. Our results can explain mathematically the observed fact, which gives records during last million years, that it grew colder with a gradual increase of amplitude of climatic oscillations, and can indicate that oscillatory climate had appeared on the earth when the geographical condition had allowed it to exist. Our tentative calculations reveal that the oscillatory climate might have emerged on the earth, when a clear cryosphere had been established on the earth owing to drift of such lands as the Antarctica or Greenland from warm low-latitudes to ice-possible high-latitude regions, and when the past earth's glacial productive capacity could have come to exceed about 70% or so of the present capacity.