Geological proxies provide valuable archives of the sea-level response to past climate variability over periods of more extreme global mean surface temperatures than the brief instrumental period. To better understand the sea-level response during the most recent warm period, the Holocene, the HOLocene SEA-level variability (HOLSEA) working group is developing the first standardized global synthesis of Holocene relative sea-level data to: (1) estimate the magnitudes and rates of global mean sea-level change during the Holocene; and (2) identify trends in spatial variability and decipher the processes responsible for geographic differences in relative sea-level change. Here I describe efforts of the working group to compile the database, which includes over 12,000 sea-level index points and limiting data from a range of different indicators across seven continents from the Last Glacial Maximum to present. All data were compiled following standard protocol that incorporates full consideration of vertical and temporal uncertainty for each sea-level index point, including uncertainties associated with the relationship of each indicator to past sea-level and the methods used to date each indicator. Finally, I discuss applications of the database to define thresholds of coastal wetland ecosystems to rapid rates of sea-level rise, provide high-quality constraints to tune models of the glacial-isostatic adjustment process, address open questions regarding the nature of Holocene sea levels, and improve local projections of future local sea-level rise.
University of Hong Kong, Hong Kong