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Wednesday, December 16, 2009

R. E. Kopp et al., Nature 462 (2009), Probabilistic assessment of sea level during the last interglacial stage

Nature 462, 863-867 (17 December 2009);  doi: 10.1038/nature08686; received 27 February 2009; accepted 11 November 2009.

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. Department of Geosciences,
  2. Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544, USA
  3. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
With polar temperatures ~3–5 °C warmer than today, the last interglacial stage (~125 kyr ago) serves as a partial analogue for 1–2 °C global warming scenarios. Geological records from several sites indicate that local sea levels during the last interglacial were higher than today, but because local sea levels differ from global sea level, accurately reconstructing past global sea level requires an integrated analysis of globally distributed data sets. Here we present an extensive compilation of local sea level indicators and a statistical approach for estimating global sea level, local sea levels, ice sheet volumes and their associated uncertainties. We find a 95% probability that global sea level peaked at least 6.6 m higher than today during the last interglacial; it is likely (67% probability) to have exceeded 8.0 m but is unlikely (33% probability) to have exceeded 9.4 m. When global sea level was close to its current level (≥-10 m), the millennial average rate of global sea level rise is very likely to have exceeded 5.6 m kyr-1 but is unlikely to have exceeded 9.2 m kyr-1. Our analysis extends previous last interglacial 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.

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