MILANKOVITCH CYCLES AND CARBONIFEROUS CLIMATE

Cyclical Permo-Carboniferous sea level fluctuations have long been lin ked to glacial-interglacial fluctuations on Gondwanaland. Similar to t he Pleistocene, such fluctuations may in turn have been driven by vari ations in orbital insolation forcing. Herein we report results from cl imate model simulations that examine the effect of Milankovitch insola tion variations on the climate of the Gondwanan supercontinent. Utiliz ing maximum summer insolation values typical of interglacials, we simu late completely snow-free conditions, with summer temperatures at the South Pole >20-degrees-C. Modifying orbital configuration to minimum s ummer insolation receipt results in a large area of below freezing tem peratures. Comparison of model-generated summer snow cover for the lat ter run with reconstructions of glacial ice extent indicates a good fi rst-order agreement. These calculations support the cyclothem model an d suggest that the entire glacial-interglacial couplet for the Carboni ferous can be simulated with a minimum number of adjustable parameters .