Global and local sea level during the Last Interglacial: A probabilistic assessment

TL;DR

This study uses a comprehensive probabilistic approach to reconstruct the Last Interglacial sea level, indicating it was likely 6-9 meters higher than today, emphasizing future sea level rise risks.

Contribution

It introduces a novel statistical method combining Gaussian process regression and MCMC to accurately estimate past global sea levels from diverse indicators.

Findings

LIG GSL was probably 6-9 meters higher than today.

Sea level rise during LIG was significant even with moderate warming.

The approach improves accuracy of past sea level reconstructions.

Abstract

The Last Interglacial (LIG) stage, with polar temperatures likely 3-5 C warmer than today, serves as a partial analogue for low-end future warming scenarios. Based upon a small set of local sea level indicators, the Intergovernmental Panel on Climate Change (IPCC) inferred that LIG global sea level (GSL) was about 4-6 m higher than today. However, because local sea levels differ from GSL, accurately reconstructing past GSL requires an integrated analysis of globally distributed data sets. Here we compile an extensive database of sea level indicators and apply a novel statistical approach that couples Gaussian process regression of sea level to Markov Chain Monte Carlo modeling of geochronological errors. Our analysis strongly supports the hypothesis that LIG GSL was higher than today, probably peaking at 6-9 m. Our results highlight the sea level hazard associated with even relatively low levels of sustained global warming.