Temperature-driven global sea-level variability in the Common Era
- aDepartment of Earth & Planetary Sciences, Rutgers University, Piscataway, NJ 08854;
- bInstitute of Earth, Ocean & Atmospheric Sciences, Rutgers University, New Brunswick, NJ 08901;
- cRutgers Energy Institute, Rutgers University, New Brunswick, NJ 08901;
- dDepartment of Earth & Ocean Sciences, Tufts University, Medford, MA 02115;
- eEarth System Analysis, Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany;
- fSea-Level Research, Department of Marine & Coastal Sciences, Rutgers University, New Brunswick, NJ 08901;
- gEarth Observatory of Singapore, Nanyang Technological University, Singapore 639798;
- hAsian School of the Environment, Nanyang Technological University, Singapore 639798;
- iDepartment of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
- jEnvironment Department, University of York, York YO10 5NG, United Kingdom;
- kDepartment of Earth & Planetary Sciences, Harvard University, Cambridge, MA 02138
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Edited by Anny Cazenave, Centre National d'Etudes Spatiales, Toulouse, France, and approved January 4, 2016 (received for review August 27, 2015)

Significance
We present the first, to our knowledge, estimate of global sea-level (GSL) change over the last ∼3,000 years that is based upon statistical synthesis of a global database of regional sea-level reconstructions. GSL varied by ∼±8 cm over the pre-Industrial Common Era, with a notable decline over 1000–1400 CE coinciding with ∼0.2 °C of global cooling. The 20th century rise was extremely likely faster than during any of the 27 previous centuries. Semiempirical modeling indicates that, without global warming, GSL in the 20th century very likely would have risen by between −3 cm and +7 cm, rather than the ∼14 cm observed. Semiempirical 21st century projections largely reconcile differences between Intergovernmental Panel on Climate Change projections and semiempirical models.
Abstract
We assess the relationship between temperature and global sea-level (GSL) variability over the Common Era through a statistical metaanalysis of proxy relative sea-level reconstructions and tide-gauge data. GSL rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability
Footnotes
- ↵1To whom correspondence should be addressed. Email: robert.kopp{at}rutgers.edu.
Author contributions: R.E.K. designed research; R.E.K., A.C.K., K.B., B.P.H., J.P.D., and W.R.G. performed research; R.E.K., K.B., C.C.H., J.X.M., E.D.M., and S.R. contributed new analytic tools; R.E.K. and K.B. analyzed data; R.E.K., A.C.K., K.B., B.P.H., J.P.D., W.R.G., C.C.H., J.X.M., E.D.M., and S.R. wrote the paper; A.C.K., B.P.H., and W.R.G. compiled the database of proxy reconstructions; C.C.H., J.X.M., and E.D.M. contributed to the design of the statistical model; and K.B. and S.R. developed and implemented the semiempirical projections.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1517056113/-/DCSupplemental.
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