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Abstract:
Because of tectonics, oceans change shape, leading to changes in the tides. We know that past tides have gone through a series of short-lived maxima above a low-energy state, but what will happen in the future? Here we present four scenarios of how the future might tectonically develop. In all four scenarios the Atlantic will continue to grow and the Pacific will continue to shrink for the next 20 or so million years. This will eventually lead to loss of the tidal resonance in the Atlantic. After that, the scenarios diverge into a closing Atlantic (Pangea Ultima), closing Pacific (Novopangea), closing of both Atlantic and Pacific (Aurica), and closing the Arctic (Amasia). In all scenarios but Amasia, tidal dissipation rates peak and fall as growing and shrinking oceans go in and out of resonance as the next supercontinent assembles over the next 200–250 Myr (million years). Once each supercontinent has formed tidal dissipation rates drop to a fraction of the present-day rates, agreeing with previous work that tides during supercontinent tenure are weak because the large super ocean that surrounds each supercontinent is too large to be resonant. These results suggest that as long as there is plate tectonics and a supercontinent cycle on Earth, the tides will continue to vary on geological time scales.
