Drivers of Common Era sea-level change in southeastern Australia: extending tide-gauge records and developing a network of high-resolution reconstructions for regional analyses.

Abstract

Southern Hemisphere observational records of sea-level change are rare prior to ~1950, making it difficult to close historical regional sea-level budgets and quantify individual contributions to sea level (e.g. barystatic, thermosteric). Recent work generated four microfossil-based high-resolution sea-level reconstructions from southeastern Australia, all of which indicated rapid regional rates of 20th century sea-level rise compared to the global average. However, unlike analogous work in the North Atlantic (for which there is a high-density network of high-resolution reconstructions), there remains a paucity of proxy data from the Southern Hemisphere, hindering a probabilistic estimate of regional drivers of relative sea level using a spatio-temporal model. We generate two new reconstructions using salt-marsh foraminifera from King Island, Tasmania, and Venus Bay, Victoria, to add to a growing database of Common Era sea-level reconstructions from southeastern Australia (and indeed wider Australasia). Fossil foraminifera indicate a rising palaeomarsh over the last ~150 years of ~0.15-0.25 m (average); this is interpreted as relative sea-level rise consistent with patterns observed in recent reconstructions. A chronology for the core is developed using both 14C and lead isotopes. Ongoing efforts to supplement the regional database will allow us to determine local and regional drivers of relative sea-level change in the region.