ti s

s th infl e s lum rn Hem te vari proxy to explain the orbital control on advances and retreats of the NH ice sheets. According to the theory, changes in high-latitude summer insolation are the main control on ice sheet expansion and This discrepancy betweenMilankovitch theory and the global ice volume record has been coined the ‘‘41 kyr problem’ ’ (Raymo and Nisancioglu, 2003). The prevalence of the obliquity signal in the Pleistocene global ice volume record has been attributed to factors including the state of the tropical Pacific Ocean (Philander and Fed