Sea Level and Storm Hazards: Past and Present

Statement of Problem: Sea-level rise and associated storm surges are major threats to low-lying areas of U.S. coastal zones, including much of the East Coast. To fully understand how high and how fast sea level may rise and what the impacts will be, it is necessary to examine past geological sea level records. These records are preserved in ancient marine shorelines (barrier islands, scarps) and sediments deposited along the Atlantic Coastal Plain (ACP) of the eastern U.S. Using new dating methods and paleoclimate proxies, the project will document past sea level variability during warm intervals, improve estimates of regional tectonic and isostatic adjustment, and support local and regional efforts to anticipate patterns and impacts of future sea level change.

Why this Research is Important: Current state-of-the-art predictions call for 1 meter of sea level rise by the year 2100, and estimates of infrastructure damage and potential loss of life from sea level rise over the next few decades require improved model capabilities. Although a sea level rise of 1 meter would likely devastate most eastern U.S. coastal regions, but the impact would be minor compared to the 6 meter rise that occurred during the last interglacial period. It is therefore imperative to understand how fast sea level rose in the past and why so that we can better try to predict and prepare for the future.

Objective(s): This project investigates patterns, causes and impacts of past sea level change along different coastlines to meet the following objectives:

• Determine the ages of past sea level highstands (peak levels above what is seen today) along the U.S. Atlantic coast and identify which ice sheets contributed to these globally higher past sea levels.
• Construct sea level curves and polar ice volume curves (graphs of changes throughout history).
• Examine the relationship between historic and past hurricane and storm activity, sea level and climate change.
• Conduct research on the last deglacial sea-level rise in the Arctic Ocean, sea-level history of the Hawaiian Islands, and paleo-sea level variation in Gulf of Corinth
• Extend the modern tide gauge record (currently limited to about 100 years back) using historical 18th and 19th century surveying which will allow assessment of sea-level rise acceleration.

Methods: The project will use various geochronological methods, stratigraphy, geomorphology, physical, biological, and chemical proxies to date east coast sediments and microfossil groups as relative sea level indictors. Elevations of paleo-sea level high stands will be assessed using geophysical models of uplift and subsidence as well as models of ice volume. Past storm activity will be assessed using coarse-grained overwash deposits found in coastal sedimentary archives.