Global Common Era sea-level
This new global database contains 1344 sea-level index points derived from multi-proxy evidence to delimit global sea-level (GSL) trends over the past ~3000 years. The database is organized alphabetically by region and includes latitude and longitude of all study sites together with the original reference and type of indicators used. The position of former relative sea-level is provided together with vertical (±1σ) and temporal (±2σ) uncertainties.
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.
Atlantic coast of the United States
The Holocene sea-level database for the Atlantic coast of the United States contains 492 index points, which locate the position of relative sea level (RSL) in time and space, and 344 limiting dates, which constrain the minimum or maximum limit of former sea level. The majority of the index points in the database are from 6 ka BP to present, with only 7% older than 6 ka BP. Spatially, index points are distributed between Maine and South Carolina, but there is an absence of data from Georgia and the Atlantic coast of Florida.
The database is sub-divided into 16 regions based on the distance from the Laurentide Ice Sheet and are classified depending upon their susceptibility to compaction. The index points and limiting data demonstrate that RSL did not exceed present (0 m) during the Holocene except in regions 1 and 2 (Eastern Maine and Southern Maine, where a sea-level low stand indicates that RSL dropped from above present prior to 9 ka BP. Rates of RSL change were highest during the early Holocene and have decreased over time, due to the diminishing response of the Earth’s mantle to glacial isostatic adjustment and reduction of ice equivalent meltwater input.
Pacific coast of central North America
A database of relative sea-level data for the past 16 ka constrains the sea-level histories of the Pacific coast of central North America (southern British Columbia to central California). The database contains 600 sea-level index points and 241 sea-level limiting points. We sub-divided the database into 12 regions based on the availability of data, tectonic setting, and distance from the former Cordilleran ice sheet. Most index (95%) and limiting points (54%) are <7 ka; older data comes mainly from British Columbia and San Francisco Bay. The stratigraphic position of points was used as a first-order assessment of compaction. Formerly glaciated areas show variable RSL change; where data are present, highstands of RSL occur immediately post-deglaciation and in the mid to late Holocene. Sites at the periphery and distant to formerly glaciated areas demonstrate a continuous rise in RSL with a decreasing rate through time due to the collapse of the peripheral forebulge and the reduction in meltwater input during deglaciation. Late Holocene RSL change varies spatially from falling at 0.7 ± 0.8 mm/yr in southern British Columbia to rising at 1.5 ± 0.3 mm/yr in California. The different sea-level histories are an ongoing isostatic response to deglaciation of the Cordilleran and Laurentide Ice Sheets.
Malay Thai Peninsula
The sea-level database (81 index points and 12 limiting data) from the Malay-Thai Peninsula reveal an upward trend of Holocene relative sea level from a minimum of -22 m at 9.7 – 9.2 ka to a mid-Holocene high stand of 4.8 – 4.4 ka, which equates to a rise of c. 5.5 mm/yr. The sea-level fall from the high stand is steady at c. -1.1 mm/yr. Geophysical modelling shows that hydro-isostasy contributes a significant spatial variation to the sea-level signal between some site locations (3-4 m during the mid-Holocene), indicating that it is not correct to construct a single relative sea-level history for the Malay-Thai Peninsula.