A better understanding of the Earth's climate requires a better understanding of the interaction between the planet's geophysical processes and the dynamics of the Solar System as a whole. So suggest University of Toronto physicist Jerry Mitrovica and Allessandro Forte of the Institut de Physique du Globe de Paris. The pair reached their conclusion based on numerical simulations that show a connection between Earth's changing shape and the gravitational effects of other bodies in the Solar System, particularly Jupiter and Saturn. "We're showing for the first time that changes in the Earth's shape, when coupled with the gravitational effects from other planets, can produce large changes in the Earth's climate," Mitrovica says, citing numerical simulations to show that these aspects of the Earth's orbit have been affected by the gravitational attraction of Saturn and Jupiter. His figures indicate that at some time during the last 20 million years, the Earth passed through a gravitational resonance associated with the orbits of Jupiter and Saturn, which in turn influenced the way the Earth's axial tilt changed during the same period. This gravitational pull would have had a much greater impact on the Earth millions of years ago when the Earth was shaped differently. For more information, contact Jerry Mitrovica at (416) 978-4946.