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Climate Simulations of Hot House (Cenomanian/Turonian) and Ice House (Early Permian) Worlds: Comparisons and Contrasts

Tom Moore1, Christopher Scotese2, Harold Illich3, John Zumberge3, and Marty Perlmutter4
1 PaleoTerra, Bollingbrook, IL
2 PALEOMAP Project, Arlington, TX
3 GeoMark Research, Houston, TX
4 Chevron Energy Technology Company, Houston, TX

During the past 600 million years the Earth's climate has alternated between Hot House conditions (no permanent polar ice cap) and Ice House conditions (polar ice cap present). In this paper we compare and contrast climate simulations for the Cenomanian/Turonian (93.5 Ma) and the Early Permian (280 Ma), respectively. The goal is to better understand: which features of the Earth's climate system are stable under these extremely different conditions, which features are most variable, how the style of equator-to-pole energy transfer changes under these two very different regimes, the relative importance of Milankovitch forcing, the correlation between source rock productivity and the global climate system, as well as the nature of the transition from Hot House to Ice House worlds, and vice versa.

During the past 600 million years there have been four major Ice House worlds: Late Precambrian, Late Ordovician, PermoCarboniferous, and Late Cenozoic. In addition, there have been two minor excursions towards Ice House conditions (Late Devonian and early Cretaceous). During the Phanerozoic, the total time interval for Ice House conditions has been approximately 110 million years (20%). Either Hot House or Ice House conditions generally prevail (90% of the time). This suggests that positive feedback mechanisms drive the climate system from one climatic extreme to the other in relatively shorts period of time, geologically speaking.

When the history of the Earth's climate is compared with temporal trends in source rock productivity, a positive correlation can be found between Hot House worlds and times of greater than average source rock productivity. All major Oceanic Anoxic Events (OAEs) occur during times of Hot House climate. We will consider how aspects of the Earth system (ocean, atmosphere, biosphere, cryosphere) favor source rock production during times of Hot House climate, and in particular, how Hot House climates spawn OAE events.