A warming followed by a drop in global temperature is observed in Middle Miocene strata. This short global warming event may be linked to the evolution and expansion of the grassland biome and may have subsequently contributed to the cooling trend that following. A palynological study of sediments from the Miocene Calvert Cliffs of Maryland identified a set of regional vegetation changes consistent with those predicted. Additionally, a SimEarth computer simulation model was implemented to examine how grasses effect global climatic conditions. Finally, vegetation/climate feedback mechanisms were analyzed to identify links affected by changes in terrestrial vegetation. Feedback mechanisms examined here include the effects of replacing multistory vegetation with single story vegetation on atmospheric carbon dioxide concentrations, chemical weathering, evapotranspiration, albedo, and atmospheric methane concentrations.
