the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Glacial-interglacial variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: simulations with the Community Climate System Model
N. G. Heavens
N. M. Mahowald
G. S. Soreghan
M. J. Soreghan
C. A. Shields
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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RC C675: 'Referee comment on cp-2012-54', Anonymous Referee #1, 27 Jun 2012
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RC C681: 'Review of “Glacial-interglacial variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: simulations with the Community Climate System Model”', Anonymous Referee #2, 28 Jun 2012
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AC C1291: 'Reply to Anonymous Referee #1', Nicholas Heavens, 18 Aug 2012
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AC C1292: 'Reply to Anonymous Referee #2', Nicholas Heavens, 18 Aug 2012
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EC C1339: 'Editors comment', Alan Haywood, 23 Aug 2012


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RC C675: 'Referee comment on cp-2012-54', Anonymous Referee #1, 27 Jun 2012
-
RC C681: 'Review of “Glacial-interglacial variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: simulations with the Community Climate System Model”', Anonymous Referee #2, 28 Jun 2012
-
AC C1291: 'Reply to Anonymous Referee #1', Nicholas Heavens, 18 Aug 2012
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AC C1292: 'Reply to Anonymous Referee #2', Nicholas Heavens, 18 Aug 2012
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EC C1339: 'Editors comment', Alan Haywood, 23 Aug 2012
N. G. Heavens et al.
N. G. Heavens et al.
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Cited
5 citations as recorded by crossref.
- Upland Glaciation in Tropical Pangaea: Geologic Evidence and Implications for Late Paleozoic Climate Modeling G. Soreghan et al. 10.1086/675255
- Dynamic Carboniferous tropical forests: new views of plant function and potential for physiological forcing of climate J. Wilson et al. 10.1111/nph.14700
- Late Pennsylvanian–Early Permian vegetational transition in Oklahoma: Palynological record R. Lupia & J. Armitage 10.1016/j.coal.2013.06.003
- Abrupt and high-magnitude changes in atmospheric circulation recorded in the Permian Maroon Formation, tropical Pangaea M. Soreghan et al. 10.1130/B30840.1
- A paleogeographic approach to aerosol prescription in simulations of deep time climate N. Heavens et al. 10.1029/2012MS000166