Preprints
https://doi.org/10.5194/cpd-8-1915-2012
https://doi.org/10.5194/cpd-8-1915-2012

  25 May 2012

25 May 2012

Review status: this preprint was under review for the journal CP but the revision was not accepted.

Glacial-interglacial variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: simulations with the Community Climate System Model

N. G. Heavens1, N. M. Mahowald1, G. S. Soreghan2, M. J. Soreghan2, and C. A. Shields3 N. G. Heavens et al.
  • 1Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, USA
  • 2ConocoPhillips School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma, USA
  • 3Climate Change Research Section, Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, Colorado, USA

Abstract. The Late Paleozoic Ice Age (LPIA), the Earth's penultimate "icehouse climate", was a critical time in the history of biological and ecological evolution. Many questions remain about the connections between high-latitude glaciation in Gondwanaland and low-latitude precipitation variability in Pangaea. We have simulated the Earth's climate during Asselian-Sakmarian time (299–284 Ma) with the Community Climate System Model version 3 (CCSM3), a coupled dynamic atmosphere-ocean-land-sea-ice model. Our simulations test the sensitivity of the model climate to direct and indirect effects of glaciation as well as variability in the Earth's orbit. Our focus is on precipitation variability in tropical (30° S–30° N) Pangaea, where there has been the most interpretation of glacial-interglacial climate change during the LPIA. The results of these simulations suggest that glacials generally were drier than interglacials in tropical Pangaea, though exceptional areas may have been wetter, depending on location and the mode of glaciation. Lower sea level, an indirect effect of changes in glacial extent, appears to reduce tropical Pangaean precipitation more than the direct radiative/topographic effects of high-latitude glaciation. Glaciation of the Central Pangaean Mountains would have greatly reduced equatorial Pangaean precipitation, while perhaps enhancing precipitation at higher tropical latitudes and in equatorial rain shadows. Variability evident in strata with 5th order stratigraphic cycles may have resulted from precipitation changes owing to precession forcing of monsoon circulations and would have differed in character between greenhouse and icehouse climates.

N. G. Heavens et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

N. G. Heavens et al.

N. G. Heavens et al.

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