Professor Benjamin Horton, of the Department of Environmental Sciences at the University of Pennsylvania, was a CWC Seminar Series speaker on March 5th. His talk, titled Holocene Sea-level Changes Along the Atlantic Coast of the United States, showed how he and his colleagues have been able to trace the rates of sea level change over historical and prehistorical periods.
Using a number of techniques, including the study of geological core samples to determine the biotic index (the types of organisms present in the environment) and radiocarbon dating, along with historical documentation and other indicators, they have developed a model showing sea level changes over the last 12,000 years. While the study covers most of the Eastern Seaboard of the United States, the main case study site was in North Carolina.
Sea levels change not only from the melting of ice sheets, but also because of sinking and uplifting of land masses.
They found that while sea levels have generally risen throughout this the study period, the rate of increase was stable and quite gradual. A striking change, however, occurred within the last 100 years, when the rate of sea level rise has spiked dramatically.
This raises the question of just how quickly sea levels may change over the next hundred years, and how this will interact with other climate change phenomena.