Tides and tidal torques of the world ocean since the last glacial maximum

Peltier's [1994] paleobathymetries are used to investigate tides and corres ponding balances of torques of the world ocean since the last glacial maxim um 21,000 years before present. Simulations with a numerical tidal model po int out that variable ice loads at the Earth's surface and rearrangements i n the interior led to considerable modifications of the resonance behavior of the oceans; Associated evident changes of the tidal range were not confi ned to the vicinity of formerly ice-covered areas. In contrast to the tidal oscillation system that was subject to almost uniform changes since the be ginning of ice retreat, the dissipation rate of the M-2 tide increased dist inctly during the principal melting time fi-om 15 to 8 kyr B.P. and reached a local extreme eight thousand years ago though surface and volume of the world ocean were already very similar to present conditions. Postglacial de formations during the following two thousand years caused the decrease of t idal dissipation from the maximum value to the present-day level, indicatin g the sensibility of tidal torques and dissipation rates to comparatively s mall variations of ocean's geometry. Since the vicinity of the tidal oscill ation system to a resonance situation is more decisive with respect to tota l dissipation than the extension of shelves where most of the tidal dissipa tion is expected to take place, states of extreme dissipation rates do not necessarily coincide with extreme bathymetric conditions.