Climate change on Mars: Modeling possible glaciers

Abstract

The purpose of this dissertation is to explore the physical possibility of ancient glacial occurrences on the surface of Mars. Furthermore, I will elucidate the nature and extent of hypothetical ice sheets by modeling the ancient glacier inferred for the Hellas region. Individually, many of the proposed glacial features can indeed be interpreted as aeolian, fluvial, or another type of feature. It is, however, the spatial and temporal association of these features, and the incongruity presented by various alternative explanations, that makes the glacial theory more complete and universal than other hypotheses. The proposed glacial system has an extent on the order of two million square kilometers. My results include profiles of the Hellas glacier. In addition, calculations of erosion rates seem to imply an approximate time scale of erosion of between 110,000 and 1,440,000 years. Taking into consideration the plausible range of geothermal flux values (32 to 72 mW/m² I have also calculated the time frames to fill the Hellas pro-glacial lake, as well as lose it to the atmosphere via evaporation and/or sublimation. The majority of these values seem to point to a glacial epoch that took place over a period of 100,000 to 500,000 years. It is suggested that, similar to the Earth, Mars has two stable climate regimes whose shift is triggered at least in part by orbital forcing parameters. The warmer climate corresponds to more of a glacial climate on the Earth, while the cooler climate resembles the cold, dry environment that exists on Mars today. There is also evidence that, geologically, these features are relatively pristine, and therefore probably relatively young. This is in comparison to a Mars generally inferred to have been warmer and wetter earlier in its history. A second climatological scenario does not even call for a drastically different climate than today, with a localized hot spot or impact providing the short-lived heat and volatiles to create a glacier. Indeed, this glacier may have been cold based for a time, or warm based due to the thickness of the overlying ice combined with the geothermal gradient.