My research produces relative sea-level reconstructions at a range of temporal and spatial scales to determine the driving mechanisms behind past, present, and future changes. Active research themes include:
- High-resolution (century and decimeter scale) relative sea-level reconstructions for the past ~3000 years.
Understanding of sea-level variability during this period is limited and the response to known palaeoclimate deviations such as the Medieval Climate Anomaly, Little Ice Age and 20th century warming is unknown. These records are a benchmark against which to compare recent trends and help to calibrate predictive models by connecting global mean sea-level change to global mean surface temperature. Regional-scale studies are seeking to establish patterns and rates of sea-level change caused by climate oscillations such as the El Nino Southern Oscillation in the western Pacific Ocean.
- Fingerprinting meltwater sources.
Geophysical models predict that melting of the Greenland Ice Sheet would generate a gradient of sea level rise along the U.S. Atlantic Coast, with larger changes in the south compared to the north. I am developing new high resolution relative sea level reconstructions along the U.S. Atlantic coast and in Bermuda to test if the predicted sea level fingerprint can be identified.
- Paleocean dynamics
Changes in the strength and/or position of ocean currents redistribute ocean water on timescales from minutes to centuries. This driving mechanism results in a characteristic spatial pattern of regional sea-level change. I am using relative sea-level reconstructions in the western North Atlantic Ocean to identify and quantify late Holocene trends in ocean circulation including changes in Atlantic Meridional Overturning Circulation.
- Constraining models of glacio-isostatic adjustment.
Holocene relative sea-level reconstructions are a unique and reliable means to infer GIA beyond the instrumental period. Ongoing research in Russia and Florida is developing new field-based relative sea level reconstructions to constrain and test GIA models.
- Palaeoseismicity in Alaska.
Land-level changes caused by megathrust earthquakes are manifest in coastal sediment sequences as gradual changes in sea level interspersed with dramatic, instantaneous changes. I use techniques developed for relative sea level reconstruction on passive margins to reconstruct the timing and magnitude of past Alaskan earthquakes in a region with little or no record of palaeoseismicity, but the potential to be a source of tsunamis effecting population centers on the U.S. Pacific coast.
- Urban sea-level change.
Sea-level rise poses a hazard to the intense concentrations of population and infrastructure that are increasingly located at the coast. However, almost all existing sea-level reconstructions come from rural locations. I am reconstructing sea-level changes in New York City and Boston to develop a paleoenvironmental history for these cities and local projections for future rise.
- Wetlands and sea-level rise.
Healthy wetlands (salt marshes and mangroves) make our coastline ecologically and economically resilient to the hazards posed by storms and extreme water-level events that occur on top of rising sea level. Furthermore, they are increasingly recognized as key sinks of "blue carbon". The sediment buried beneath coastal wetlands preserves a record not only of sea-level change, but also of how these valuable ecosystems responded to past changes in sea level and climate. This offers an insight into how our coastal wetlands might respond to the rates and amount of sea-level rise expected in coming decades and centuries.