Probabilistic assessment of sea level during the last interglacial stage

Robert E. Kopp1,2, Frederik J Simons1, Jerry X. Mitrovica3, Adam C. Maloof1, and Michael Oppenheimer1,2

1 Geosciences Department
Princeton University
Princeton NJ 08544, USA

2 Woodrow Wilson School
Princeton University
Princeton NJ 08544, USA

3 Department of Earth & Planetary Sciences
Harvard University
Cambridge MA 02138, USA

Nature, 2009, 462, 863-867, doi:10.1038/nature08686
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With polar temperatures ~2-5°C warmer than today, the Last Interglacial (LIG) stage serves as a partial analogue for 1-2°C global warming scenarios. Geological records from several sites indicate that LIG local sea levels (LSLs) were higher than today, but because LSLs differ from global sea level (GSL), accurately reconstructing past GSL requires an integrated analysis of globally distributed data sets. Here we present an extensive compilation of LSL indicators and a novel statistical approach for estimating GSL, LSLs, ice sheet volumes and their associated uncertainties. We find a 95% probability that LIG GSL peaked at least 6.6 m higher than today. It likely (67% probability) exceeded 8.0 m but is unlikely (33% probability) to have exceeded 9.4 m. When GSL was close to its current level (>-10 m), the millennial average rate of GSL rise very likely exceeded 5.6 m/ky but is unlikely to have exceeded 9.2 m/ky. Our analysis extends previous LIG sea level studies by integrating literature observations within a probabilistic framework that accounts for the physics of sea level change. The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming.


  1. Figure 01 Site map
  2. Figure 02 Data map
  3. Figure 03 Diagram of the statistical network analysis
  4. Figure 04 Full sea level analysis
  5. Figure 05 Exceedance plots

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