A database of biological and geomorphological sea-level markers from the Last Glacial Maximum to present

Abstract

The last deglacial was an interval of rapid climate and sea-level change, including the collapse of large continental ice sheets. This database collates carefully assessed sea-level data from peer-reviewed sources for the interval 0 to 25 thousand years ago (ka), from the Last Glacial Maximum to the present interglacial. In addition to facilitating site-specific reconstructions of past sea levels, the database provides a suite of data beyond the range of modern/instrumental variability that may help hone future sea-level projections. The database is global in scope, internally consistent, and contains U-series and radiocarbon dated indicators from both biological and geomorpohological archives. We focus on far-field data (i.e., away from the sites of the former continental ice sheets), but some key intermediate (i.e., from the Caribbean) data are also included. All primary fields (i.e., sample location, elevation, age and context) possess quantified uncertainties, which—in conjunction with available metadata—allows the reconstructed sea levels to be interpreted within both their uncertainties and geological context.

The Sensitivity of the Antarctic Ice Sheet to a Changing Climate: Past, Present, and Future

“…However, further evidence for an Antarctic contribution to MWP-1a from data on land and the continental margin in other regions such as the Weddell Sea (Arndt et al, 2017;Nichols et al, 2019) is absent, and this issue remains a conundrum (Goehring et al, 2019;Hall et al, 2015;Prothro et al, 2020). The large uncertainties in the underpinning sea level constraints (Hibbert et al, 2016(Hibbert et al, , 2018Stanford et al, 2011), and dating of geological material on land and in the ocean (e.g., see discussion of cosmogenic dating in Siegert et al (2019) and radiocarbon dating in Anderson et al (2014)), and the uncertainty around the AIS size, seaward extent, thickness and volume above flotation at the LGM, mean that currently it remains difficult to quantify the exact contribution of AIS melting to the sea level rise recorded during MWP-1a. Ocean forcing was inferred as the key driver of deglacial AIS dynamics, modulated by global atmospheric teleconnections, that decoupled ice sheet elevation and air temperatures in a high resolution ice core near the Weddell Sea, and resulted in rapid thinning of the AIS during the period coinciding with MWP1-a (Fogwill et al, 2017).…”

Development of anchialine cave habitats and karst subterranean estuaries since the last ice age

“…A new database of sea-level indicators from Bermuda was compiled from earlier work 52,53,86–89 that is mostly derived from basal peat in contact with limestone (Supplementary Dataset). This database is currently unavailable in other databases of global sea-level indicators 67 . The radiocarbon-dated sedimentary deposit is these earlier works is often designated simply peat, without any differentiation between brackish and freshwater peat using preserved microfossils (i.e., defined indicative meaning).…”

“…The radiocarbon-dated sedimentary deposit is these earlier works is often designated simply peat, without any differentiation between brackish and freshwater peat using preserved microfossils (i.e., defined indicative meaning). Nevertheless, much of the new database compiled here is derived from peat collected at the limestone contact 52,89 , and thus can still be conservatively used as maximum sea-level indicators (terrestrial limiting) 67 .…”

“…Terrestrial and freshwater peat deposits recovered in contact with the carbonate platform from Bermuda provide maximum sea-level indicators (Fig. 4), which constrain glacioisotatic processes and past sea levels 67 . In contrast, cave sedimentary deposits are minimum sea-level indicators because groundwater must have achieved this elevation for aquatic habitats develop 58 .…”

Sedimentary unknowns constrain the current use of frequency analysis of radiocarbon data sets in forming regional models of demographic change

“…As a first practical step, a large‐scale compilation of archaeological chronologies would benefit from (i) information on sites and artefacts (e.g., Anderson, 1990; Faught et al, 1994) and (ii) geological and sedimentary information (including palaeoenvironmental data) for context. A number of large data sets exist that do include contextual data, and they include data related to fossils (Peters et al, 2019), geological cosmogenic and luminescence data (Codilean et al, 2018), sea level (Hibbert et al, 2018) and palaeoclimate (AUS‐INTIMATE, SHAPE; Lorrey, 2016). The only archaeological database we are aware of that specifically includes contextual data is that of Bevan et al (2017).…”