The topography of the Earth exerts an extremely important influence on atmospheric circulation patterns and both floral and faunal biogeography. However, the uplift history of many large tectonic structures, such as the Himalayas and Tibetan Plateau, and the changes in paleo-topography of the Earth through time, remain among the least well-quantified, yet critical boundary conditions in the study of both climatic and biotic evolution. The proposed research aims to develop, validate and precisely quantify the associated errors of a novel paleo-altimeter, which will be based on the predictable changes in CO2 partial pressure (Pa) with altitude, as reflected in stomatal frequency (density and index) of fossil plant taxa. The reduction in CO2 Pa with altitude exerts a physiological limitation on plant photosynthesis, which is compensated for, in many species, by an increase in stomatal frequency and altered stomatal distribution. As the partial pressure of atmospheric CO2 decreases with altitude in a predictable manner, and stomatal frequency on plant leaves increases significantly with decreasing partial pressure, theoretically therefore, paleo-elevation can be estimated by calculating the difference in CO2 Pa (estimated from fossil leaf stomatal frequency) between coeval high elevation and sea-level fossil floras. It is projected based on preliminary modeling that this CO2 Pa based method will yield paleo-elevations within an estimated error of 500 m and yield results, based on temperature sensitivity analysis, which are independent of climate, therefore providing significant improvements on existing methodologies.
