The Influence of Water Storage in Marine Sediment on Sea‐Level Change

Abstract

Sea‐level changes are of wide interest because they provide information about Earth's internal structure and the sensitivity of ice sheets to climate change. Here we illustrate the sensitivity of sea level to marine sedimentary water storage by modeling sea‐level responses to a synthetic global sediment redistribution history in which rates and patterns of erosion and deposition are similar to those at present and steady in time from the Last Interglacial to present. Our simulations show that if sediment redistribution were accounted for but sedimentary water storage were neglected, modeled sea‐level changes could be overestimated by ~2 ± 1 m of global mean sea‐level equivalent, a significant fraction of published estimates of 6–9 m of global mean sea‐level change since the Last Interglacial. These results show that sedimentary water storage may significantly contribute to changes in Earth's long‐term seawater budget over >105 year timescales and underscore the importance of accounting for it in modeling long‐term sea‐level changes.

Towards assessing the influence of sediment loading on Last Interglacial sea level

“…Sediment loading is one such process potentially contaminating the sea level record. While regional studies have shown sediment can influence sea level on glacial timescales (Simms et al 2007(Simms et al , 2013Wolstencroft et al 2014;Ferrier et al 2015Ferrier et al , 2018Pico et al 2016), in this paper we pose the question globally: to what extent might sediment loading control the variability of LIG sea level observations, and where are these effects most substantial?…”

Sea-level responses to rapid sediment erosion and deposition in Taiwan

“…For depositional areas, we follow Ferrier et al (2017Ferrier et al ( , 2018 in computing the rate of change of sediment thickness as the difference between the rates of deposition and compaction, with sediment deposited at an initial porosity of 0.6 and compacting at a rate given by Equation 2.…”

“…Here f(z) is the porosity at depth z below the sediment surface, fmin is the minimum porosity in fully compacted sediment, k is a compaction coefficient, and sd(z) is the difference between lithostatic and hydrostatic stress at depth z, which depends on the sediment grain density rs and water density rw. Following Ferrier et al (2017Ferrier et al ( , 2018, we adopt values of rs = 2700 kg m -3 , rw = 1000 kg m -3 , fmin = 0.2, and k = 10 -17 Pa -1 s -1 . This approach yields vertical profiles of sediment density and porosity that vary over time, which we use to compute time series of mean sediment column density ̅ !…”

“…These studies have shown that sediment deposition can affect inferences of past sea level by several meters on millennial timescales (e.g., Dalca et al, 2013;Ferrier et al, 2015) and tens of meters over Myr timescales (e.g., Moucha and Ruetenik, 2017) by inducing isostatic responses and modifying the gravitational field in an area of up to hundreds of km. Recently, the gravitationally self-consistent sea-level theory has been extended to account for sediment compaction and sediment water storage (Ferrier et al, 2017(Ferrier et al, , 2018.…”