A recent study has attempted to use a long-term (~2,100 years), local (coastal North Carolina), determination of sea level derived from the build-up of salt marsh sediments to better characterize the behavior of global sea level (and by proxy, global temperatures) over the same multi-millennial time period. Based upon the results of this investigation, the research team led by Andrew Kemp from the University of Pennsylvania, concludes that there were four rather distinct periods of sea level rise over the past 2,100 years. Here is how they describe the first three:
Sea level was stable from at least BC 100 until AD 950. Sea level then increased for 400 y at a rate of 0.6 mm/y, followed by a further period of stable, or slightly falling, sea level that persisted until the late 19th century.
And then, and here’s the kicker (and why this paper received all the press coverage that it did, with headlines such as “Fastest Sea-Level Rise in 2,000 Years Linked to Increasing Global Temperatures“):
Since then, sea level has risen at an average rate of 2.1 mm/y, representing the steepest century-scale increase of the past two millennia. This rate was initiated between AD 1865 and 1892. Using an extended semiempirical modeling approach, we show that these sea-level changes are consistent with global temperature for at least the past millennium.
But can a paleo-record of sea level rise from basically one locality (e.g., coastal North Carolina) provide a good indication of the long-term history of global sea level rise? Obviously, the authors think so, but others are not so sure.