Towards a global atlas of Holocene sea levels: leveraging decades of legacy efforts

Abstract

As early as 2500 years ago, beginning with Pythagoras, scientists have recognized that the relative positions of the land and sea have not remained stable through time. The concept of 'eustasy,' first termed by Suess in 1888, explains the transfer of water between the oceans and ice sheets during the Quaternary as ice sheets grew and melted during successive glaciations, which in turn had a first-order control on ocean volume and sea level. With the advent of radiocarbon dating in the 1950s, widespread investigations into post-LGM sea levels on local, regional and global scales were enabled, and a concerted effort was made to compile a global 'eustatic' sea-level curve. Here we review the long legacy of efforts to establish a global atlas of relative sea-level (RSL) data, key advancements made in our understanding of RSL and uncertainties inherent in the data we use to infer these changes, placing particular emphasis on the Holocene. The first key advancement was the development of geophysical models of the glacial-isostatic adjustment (GIA) process, and the continued close interaction between the GIA and sea-level communities. Early analyses of RSL data confirmed that the eustatic curve was an immeasurable factor at any one point on Earth and that it could only ever be inferred from sea-level data at multiple locations. The second development was a more rigorous recognition of uncertainties inherent in RSL reconstructions. Most recently, formal statistical treatment has been applied to sea-level data that accounts for the sparse distribution of data in time and geographic space and uncertainties in time and elevation. Improved understanding of the mechanisms driving RSL variability will be achieved through the continued standardization of sea-level databases, which will enhance the comparability and accessibility of information to improve both geophysical models and statistical reconstructions.