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(relative sea-level rise) because of a process called glacio-isostatic adjustment and,
since the late nineteenth century, this trend has been exaggerated as the ocean surface rises because of expansion of existing water as it heats up and by melting of ice,
that adds mass to the ocean.
We only have direct measurements of relative sea level going back a few decades
in most places, but we can use geological methods, approaches, and reasoning to
reconstruct how it changed over thousands of years. In North Carolina we develop
these reconstructions by collecting cores from salt marshes and using them to establish how high relative sea level was and when it was there. Detailed reconstructions
spanning the past ~2000 years show that the high rate of relative sea-level rise in
North Carolina and globally during the twentieth century was unprecedented in the
context of the ~2000 preceding years. Prior to the twentieth century relative sealevel rise occurred almost exclusively because of the land moving downward. As we
look ahead, we can expect relative sea-level to rise at ever faster rates in North
Carolina as ongoing land subsidence occurs with a rising sea surface. But some of
that fate is in our own hands. For example, projections for Wilmington in North
Carolina predict a nine in ten chance that relative sea-level rise during the current
century will be between 42 cm and 132 cm under a business-as-usual scenario for
carbon dioxide emissions, but 24–94 cm under a scenario in which emissions are
Fig. 3.12 Coauthor Kemp taking a nap while waiting for a boat to collect the field party at the end
of a day working in mangroves along Florida’s intercoastal waterway, much to the confusion of
passing pleasure boaters. (Image by S.E. Engelhart)
A. C. Kemp and B. P. Horton
(relative sea-level rise) because of a process called glacio-isostatic adjustment and,
since the late nineteenth century, this trend has been exaggerated as the ocean surface rises because of expansion of existing water as it heats up and by melting of ice,
that adds mass to the ocean.
We only have direct measurements of relative sea level going back a few decades
in most places, but we can use geological methods, approaches, and reasoning to
reconstruct how it changed over thousands of years. In North Carolina we develop
these reconstructions by collecting cores from salt marshes and using them to establish how high relative sea level was and when it was there. Detailed reconstructions
spanning the past ~2000 years show that the high rate of relative sea-level rise in
North Carolina and globally during the twentieth century was unprecedented in the
context of the ~2000 preceding years. Prior to the twentieth century relative sealevel rise occurred almost exclusively because of the land moving downward. As we
look ahead, we can expect relative sea-level to rise at ever faster rates in North
Carolina as ongoing land subsidence occurs with a rising sea surface. But some of
that fate is in our own hands. For example, projections for Wilmington in North
Carolina predict a nine in ten chance that relative sea-level rise during the current
century will be between 42 cm and 132 cm under a business-as-usual scenario for
carbon dioxide emissions, but 24–94 cm under a scenario in which emissions are
Fig. 3.12 Coauthor Kemp taking a nap while waiting for a boat to collect the field party at the end
of a day working in mangroves along Florida’s intercoastal waterway, much to the confusion of
passing pleasure boaters. (Image by S.E. Engelhart)
A. C. Kemp and B. P. Horton