The tides sweeping across one of the world’s most powerful coastal seas are now among the strongest they have been in 21,000 years, according to new research that reconstructs how tidal energy across the Patagonian Shelf has shifted since the end of the last Ice Age – with significant implications for carbon storage, marine habitats, and our understanding of how ocean systems respond to rising seas.
The study, published in Paleoceanography and Paleoclimatology, was carried out by academics working on the Convex Seascape Survey – a five-year global ocean and climate research programme investigating how the seabed and continental shelf seas influence the Earth’s carbon cycle, implemented by Blue Marine Foundation, the University of Exeter, and Convex Insurance.
Using updated sea-level reconstructions and high-resolution tidal modelling, the team simulated tidal conditions across the Patagonian Shelf at 1,000-year intervals stretching back to the Last Glacial Maximum, when vast areas of today’s continental shelves were dry land and enormous volumes of water remained locked in global ice sheets. As those ice sheets melted and sea levels rose, the shape and position of coastlines changed – and with them, the behaviour of the tides.
What the researchers found was not a simple, steady increase in tidal energy as the sea rose. Instead, the shelf’s evolving geometry produced abrupt reorganisations in tidal behaviour. The dominant twice-daily tide – driven by the Moon’s gravitational pull – reached peak energy around 10,000 years ago, with dissipation running approximately 16% higher than today. A second tidal component proved even more sensitive to changing conditions, peaking at around 50% above present-day levels some 15,000 years ago.
The Patagonian Shelf is now, the research suggests, experiencing some of its most energetic tidal conditions since the Ice Age ended.
“Continental shelf seas are dynamic systems, and tides are one of the key forces shaping them,” said Dr Sophie Ward, lead author and physical oceanographer at Bangor University. “By reconstructing how tides changed across the Patagonian Shelf over thousands of years, we can see that sea-level change can reorganise tidal energy in complex and sometimes abrupt ways. This matters because tides influence sediment transport, habitats, coastal evolution and the processes that help lock organic carbon away in the seabed.”
