Sediment loading from the Río de la Plata as a driver of regional sea-level variability

Sea-level reconstructions are critical benchmarks for testing models of ice-sheet stability and climate change. Their interpretation, however, is complicated by sea-level changes driven by different processes, among which the Earth’s response to sediment loading. Here we show that incorporating sediment isostasy reduces long-standing discrepancies among Marine Isotopic Stage (MIS) 5a and 5e records from the Río de la Plata estuary by up to an order of magnitude, demonstrating that regional sedimentary histories can shift relative sea-level estimates by several meters compared to traditional GIA-based approaches. We further demonstrate that sediment loading has influenced relative sea level throughout the Holocene and continues to affect modern tide-gauge records from the area. These findings underscore the importance of regionally resolved sedimentation histories, in contrast to approaches based solely on global compilations, and highlight the need for expanded shelf coring and seismic surveys.