  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.
