Astronomical solutions for paleoclimate computations
CNRS, Observatoire de Paris
Jeudi 29/06/2017, 11h00-12h00
Bat 701, P 17C, LSCE Orme des Merisiers
According to Milankovich theory, the large climatic variations of the past are triggered by the insolation changes on the surface of the Earth that result from the variations of its orbit and orientation which are themselves the consequences of the gravitational interactions among the planets. The first long term solution for the motion of the solar system is due to Lagrange, in the XVIII th century, but it was the further solution of Le Verrier, in 1840 that was used by Croll to build his scenario for the explanation of the ice ages. Since then, the accuracy of the orbital and rotational solutions for the Earth have largely improved and allowed in 2004, the astronomical calibration of the Neogene. This calibration was performed using the correlation of the sedimentary record with the astronomical solution. Nevertheless, the chaotic motion of the orbits of the solar system (Laskar, 1989) puts a limit to the possibility of obtaining an accurate solution for the past evolution of the Earth's orbit to about 60 Myr. Going beyond this barrier is still possible using the most stable parts of the orbital solution.