DRAWBACKS OF USING THE THERMODYNAMIC PALEOALTIMETRY METHOD

The focus of this work is to highlight the strengths and weaknesses of the thermodynamic paleoaltimetry method or paleoenthalpy method. The paleoentalphy method is predicated upon the annual mean atmospheric temperature profile along an air mass trajectory being close to a moist adiabat. Rigorous tests of this method are lacking, however. As a self-consistent assessment of this method, we simulate a suite sensitivity tests on is the Himalayan-Tibetan complex. The model presented in this study is the family of climate models developed by the National Center for Atmospheric Research: Community Climate System Model version 3 and 4, and the Community Earth System Model. The three questions we highlight are (1) how does simulating the climate system in a higher model resolution impact the paleoenthaly estimates, (2) is there an elevation limit to the method, and (3) how does altering the climate system to a warmer world impact estimates.

Our results demonstrate that changing the model resolution has a small impact, which is crucial for future application of this method. However, planetary-scale changes to the Tibetan Plateau elevation suggest that the paleo-enthalpy method is unreliable with low and high mountain ranges. Lastly, moist static enthalpy estimates increase as we increased global temperature, which results in a decrease in calculated maximum elevation. In general, calculated paleo-enthalpy has a 1 km uncertainty [Forest, 2007] and such uncertainty increases as we increase global mean temperatures.