The Impact of Glacio-Mediated Sea Level Changes on the Tides in the Past and Future

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• Sophie-Berenice Wilmes, Bangor University
• Wednesday 04 February 2015, 11:00-12:00
• British Antarctic Survey, Room 307.

If you have a question about this talk, please contact Dr Dan Jones.

If external to BAS, please email the organizer in advance for building access

Recent studies have highlighted an accelerated ice loss from glaciers draining the West Antarctic and Greenland Ice Sheets. In West Antarctica a marine ice sheet destabilization may already be underway, possibly leading to a collapse of the ice sheet in the coming centuries. A full melting of either ice sheet would not result in a globally uniform sea level increase, but in spatially heterogeneous sea level changes due to changes in gravitational attraction, the Earth’s rotation and crustal unloading. During the Last Glacial Maximum (LGM; 18–22 kyr BP) sea level was on average 120 m lower than today due to large amounts of water being locked up in the Northern Hemisphere ice sheets. Because ocean tides are largely controlled by the bathymetry these sea level changes are expected to impact on the dynamics of the global tides. Here, we investigate how the tides, and the associated tidal energy dissipation, respond to the large, non-uniform sea level changes the changes in ice sheet configuration would induce. We show that large changes in amplitude for the principle semi-diurnal constituent M2 would occur across the globe both in the future and the past scenarios. Furthermore, large changes in tidal energy dissipation take place both in the deep ocean and in most tidally dominated shelf seas, with potential consequences for ocean mixing, biogeochemistry, and tidal power extraction, and in the case of the LGM also for ocean circulation. Our results replicate previously reported enhancements in dissipation and amplitudes for M2 for the LGM and provide a detailed picture of the large global changes in M2 tidal dynamics occurring over the deglaciation period. We show that for M2 the grounding line location has a large influence on global tides. For K1 the changes over this period are mainly regional and not are impacted by grounding line shifts. Our work shows that glacio-mediated sea level changes may have had profound impacts on the tides in the past and are expected to do so in the future.

This talk is part of the British Antarctic Survey - Polar Oceans seminar series series.

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