Tuesday, December 18, 2012

New paper finds sea levels were significantly higher during past interglacials

A paper published today in Quaternary Research finds sea levels on the island of Curaçao [southern Caribbean] during the last interglacial were up to 9 meters higher than the present, and that during another interglacial period 400,000 years ago sea levels were up to 20 meters higher than the present. According to the paper, these significantly higher sea levels during prior interglacials "require major ice sheet loss from Greenland and Antarctica." The authors determine sea levels by dating fossilized reefs that are presently located high above current sea levels [photo below]. The paper also shows sea levels in the Red Sea were up to ~8 meters higher than the present within the past 5,000 years of the current interglacial, and up to ~12 meters higher than the present during the last interglacial. This and many other papers debunk claims by climate alarmists that recent sea level rise is unprecedented, unnatural, or accelerated. In fact, sea levels rose at a constant rate without acceleration during the 20th century, and have decelerated since 2005 to a rate of only ~1.2 mm/yr [less than 5 inches per century].


Top graph shows sea levels relative to the present during 3 prior interglacials. Bottom graph shows the Red Sea levels for comparison.

Fossilized reefs [shown by dotted lines] formed when sea levels were much higher than the present.

Sea-level history of past interglacial periods from uranium-series dating of corals, Curaçao, Leeward Antilles islands

  • a U.S. Geological Survey, MS 980, Box 25046, Federal Center, Denver, CO 80225, USA
  • b Australian Research Council Centre of Excellence for Coral Reef Studies and School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia

Abstract

Curaçao has reef terraces with the potential to provide sea-level histories of interglacial periods. Ages of the Hato (upper) unit of the “Lower Terrace” indicate that this reef dates to the last interglacial period, Marine Isotope Stage (MIS) 5.5. On Curaçao, this high sea stand lasted at least 8000 yr (~ 126 to ~ 118 ka). Elevations and age of this reef show that late Quaternary uplift rates on Curaçao are low, 0.026–0.054 m/ka, consistent with its tectonic setting. Ages of ~ 200 ka for corals from the older Cortalein unit of the Lower Terrace correlate this reef to MIS 7, with paleo-sea level estimates ranging from − 3.3 m to + 2.3 m. The estimates are in agreement with those for MIS 7 made from other localities and indicate that the penultimate interglacial period was a time of significant warmth, on a par with the present interglacial period. The ~ 400 ka (MIS 11) Middle Terrace I on Curaçao, dated by others, may have formed from a paleo-sea level of + 8.3 to + 10.0 m, or (less likely) + 17 m to + 20 m. The lower estimates are conservative compared to previous studies, but still require major ice sheet loss from Greenland and Antarctica
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6 comments:

  1. Can one conclude that the land itself has not risen and fallen in this time period?

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    Replies
    1. According to the paper:

      "Elevations and age of this reef show that late Quaternary uplift rates on Curaçao are low, 0.026–0.054 m/ka, consistent with its tectonic setting."

      I'm sure the authors take this into consideration to determine the sea levels

      Delete
    2. How can they track the rising/sinking of the reef over time?
      They've only just starting to be able to do this with satellites.

      Delete
    3. http://en.wikipedia.org/wiki/Post-glacial_rebound

      Delete
  2. http://www.princeton.edu/geosciences/people/maloof/pdf/Kopp2009b.pdf

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  3. http://www.google.com/gwt/x?source=reader&u=http://www.washingtontimes.com/news/2012/dec/17/sea-level-rise-data-based-on-shoddy-science/print/%23ixzz2JHQed7qp&ei=9ZAGUamuA6qGkgKf-oGIDg&wsc=pb&ct=pg1&whp=30

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