Astronomical solutions for paleoclimate studies over the last 3 million years

Abstract

Three solutions (numerical—QTD90, semi-analytical—LA90 and analytical—BER90) for the planetary and precessional elements of the Earth have recently become available. They allow the computation of the fundamental astroclimatic parameters (eccentricity, climatic precession and obliquity). The agreement between these different solutions is remarkably good, reflecting their accuracy, in such a way that they can be considered reliable enough for paleoclimate studies over at least 3 Myr. The difference between these solutions in eccentricity is less than 0.005 over this time interval, while the differences in obliquity and climatic precession are larger but mainly due to phase lag between the solutions. At 3 Myr BP, BER90 leads LA90 by 6 × 10 3 yrs and QTD90 by 9 × 10 3 yrs for the obliquity, and it leads LA90 by 2 × 10 3 yrs and QTD90 by 4 × 10 3 yrs for the climatic precession.