Data–model comparison of Holocene sea-level change in the circum-Caribbean region

Abstract

Relative sea-level (RSL) reconstructions from the circum-Caribbean region were interpreted using a glacial isostatic adjustment (GIA) model with the aims to quantify the contribution of this process to both the temporal and spatial forms of the RSL observations and remove the GIA signal to estimate land ice volume change (eustasy) during the mid-to-late Holocene. To infer an optimal GIA parameter set, the RSL data were used to determine best-fitting Earth viscosity model parameters for two different global ice histories. The RSL data indicate a clear preference (95% confidence) for relatively high viscosity values: >0.8×1021Pas in the upper mantle and >3×1022Pas in the lower mantle. The data were not able to discriminate (at 95% confidence) between lithospheric thickness values ranging between 71 and 120km, although the thickest value considered produced the best fits. RSL predictions based on the best-fitting model parameters indicate a spatial variability across the region of up to ~7m during the early to mid-Holocene which is large enough to introduce significant error when using the entire dataset to produce a single regional RSL curve without correcting for GIA. When corrected for GIA, the most precise data from the region indicate about 3–4m of land ice melt (eustasy) from ~7calkyrB.P. to ~3–2calkyrB.P., although we note that there is considerable scatter in these corrected data. This likely reflects GIA model limitations, such as the assumption of lateral homogeneity in a region that contains several plate boundaries, the influence of tectonic processes (which were not modelled), as well as errors and an underestimate of the uncertainty in the RSL reconstructions.