Phenomenology of Ice Ages

Abstract

A parameterized fit to 5.3 million years of Benthic foram dO18 data is described, which quantifies the magnitude, phase, and variability of Milankowitz terms. The 41,000y obliquity cycle, and 100,000y ellipticity cycles are dominant, with interglacial periods correlated with large orbital ellipticity. Shorter regular warming peaks correlate with larger obliquity. The fit is then used to extrapolate forward in time implying that the earth will begin cooling in about 2000 years time, eventually entering another 70,000 year long glaciation. Possible causes resulting from effects in the tropics due to increased eccentricity, and to changes in albedo at large obliquity, are discussed.