T146 Recent Sea-Level Rise: Accelerating or Not?

Tuesday, 6 November 2012
8:00 AM - 12:00 PM
218AB

SEA-LEVEL CHANGE ALONG THE ATLANTIC COAST OF THE UNITED STATES

Paper number: T146-6
Program: Technical Sessions
Time: 9:25 AM – 9:40 AM

Authors

Abstract

The rate of sea-level rise along the US Atlantic and Gulf coasts increased through the 20th century and will almost certainly continue to accelerate during the 21st century and beyond, although significant uncertainty surrounds the likely magnitude and regional variability. We have produced new high-resolution reconstructions of sea-level change for the last 2000 years along the US Atlantic Coast spanning the alternation between the so-called “Medieval Climate Anomaly”, “Little Ice Age” and 20th century warming. Innovative microfossil-based transfer functions from salt-marsh sediments are used to generate sea-level records with a vertical resolution of ± 0.1-0.3m. Combining this approach with a suite of complementary dating methods provides the ability to precisely constrain the chronology (decadal to centennial age resolution) of subtle changes in sea level. We have used the proxy data of sea-level and global temperature reconstructions to provide crucial additional constraints to the parameters in semi-empirical models of sea-level rise.

Before the models can provide appropriate data for coastal management and planning, they must be complemented with regional estimates of sea-level rise. The proxy sea-level data collected from five study areas (Massachusetts, Connecticut, New Jersey and North Carolina and Florida) exposes regional variability due to glacial isostatic adjustment (GIA) of the solid Earth. In New Jersey, Massachusetts and Connecticut GIA corrected sea level was stable from at least BC 200 until AD 500. Sea level then increased at a rate of less than 1 mm/yr resulting from/associated with the Medieval Climate Anomaly. In North Carolina the rise in sea level began slightly later at AD 950. All records show stable or falling sea level between AD 1400 and the late 19th century at the time of the Little Ice Age. Since then, sea level has risen at greater than 2 mm/yr, representing the steepest century-scale increase of the past two millennia.