Paper finds Arctic sea ice extent 8,000 years ago was less than half of the ‘record’ low 2007 level

THE HOCKEY SCHTICK
Aug 27, 2012

A paper published in Science finds summer Arctic Sea Ice extent during the Holocene Thermal Maximum 8,000 years ago was “less than half of the record low 2007 level.” The paper finds a “general buildup of sea ice from ~ 6,000 years before the present” which reached a maximum during the Little Ice Age and “attained its present (year 2000) extent at 4,000 years before the present”

Horizontal axis is number of years before the present. Multiyear sea ice reached a minimum between ~8500-6000 years ago during the Holocene Thermal Maximum (HTM).

Excerpt: In general, our sea-ice record for North Greenland follows the Holocene climate development, with an early warm period followed by declining temperatures, which were punctuated by relatively warmer and colder intervals (17, 25). The reduction of the HTM sea ice in northern Greenland fits with the simulated ice distribution and surface temperature in orbitally forced ECHAM5/JSBACH/MPI-OM (EJM) and LOVECLIM general circulation climate model simulations (3, 4, 10). A tentative first approximation of the large-scale changes associated with the observed ice retreat north of Greenland can be obtained by selecting among the numerical experiments performed with the LOVECLIM model those that are the most similar to our observations [experiments E3 to E5 (3) and fig. S3]. In this exercise, our records would correspond in the model to an Arctic Ocean sea-ice cover in summer at 8 ky B.P. that was less than half of the record low 2007 level. The general buildup of sea ice from ~6 ky B.P. agrees with the LOVECLIM model, showing that summer sea-ice cover, which reached its Holocene maximum during the LIA, attained its present (~2000) extent at ~4 ky B.P. (fig. S3)

This article was posted: Monday, August 27, 2012 at 8:17 am

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