Tracking Sea-level Source Contributions: A Hemispheric Approach to High Resolution Sea-level Variation Over the Last Two Millennia

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Accurate estimates of sea-level rise in the pre-satellite era are needed to provide appropriate context for 21st century projections and to validate geophysical and climate models. Exploring geographic trends in sea level are critical for this because sea-level changes are not globally uniform and involve isostatic deformation of the solid Earth along with gravitational and rotational changes driven by the exchange of mass between oceans and ice sheets. The aim of the study is to produce high-resolution reconstructions of sea-level change for the past two millennia along the Atlantic coasts of South Africa and Argentina. Relative sea levels along these coastlines are influenced by melting of both the Greenland and Western Antarctic Ice Sheets (GIS and WAIS). Four hypothetical hypotheses related to the timing and magnitude of sea-level changes: (1) The magnitude of sea-level rise since AD ~1850 is greater in Argentina and South Africa than New England which may indicate more ice-melt contribution from the GIS; (2) The magnitude of the deceleration in relative sea-level rise associated with the Little Ice Age (c. AD 1500-1850) is greater in New England then in South Africa or Argentina; (3) The magnitude of relative sea-level rise during the Medieval Climate Anomaly (c. AD 1000-1500) increased more in New England then in South Africa and Argentina; and (4) The magnitude of relative sea-level change prior to AD 1000 was slower than that since AD 1000 to present. New microfossil-based transfer functions approach to sea-level reconstruction in salt-marsh sediments will be used ot develop a high-resolution record. This approach combined with a suite of complementary dating methods affords the ability to precisely constrain the chronology (decadal to centennial age resolution) of subtle changes in sea level. In this project, high-resolution relative sea-level reconstructions spanning the past 2000 years will be obtained from South Africa and Argentina. And compared to existing records from New England after they have been corrected for glacial isostatic adjustment (GIA) and steric influences. This project will lead to an increased understanding of the driving mechanisms of sea-level change and could enhance predictions of 21st century sea-level rise and thus has important societal relevance. The project will support an early career PI and graduate students.