Stability of Land Surfaces in the Dry Valleys: Insights Based on the Dynamics of Sub-Surface Ice and Sand Wedge Polygons

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This award, provided by the Office of Polar Programs of the National Science Foundation, supports a project to study features of the landscape and soils of the Dry Valley region of Antarctica toward a fuller understanding of past climatic and environmental conditions. The dynamic nature of climate has received growing public attention because of the occurrence of seemingly extreme weather events recently, and growing concerns about warming. El Nino and global greenhouse warming have become familiar topics in the news. In this context, it is increasingly important to understand the inherent variability of Earth's climate and how humans affect can affect Earth's environment. One important means of improving our understanding of the Earth's climate system is to treat the Earth as a natural laboratory and examine it's past behavior. One of the most extreme changes in the Earth climate system during the last few million years is the transition from a warm period in the Pliocene to an ice age world. In Antarctica, this interval of time is thought to have seen relatively mild conditions give way rapidly to intense glacial conditions that catalyzed the growth of the largest ice sheet on Earth. This inference is based on geologic indicators of past climate from which some scientists suggest that East Antarctica was relatively warm and largely free of glaciers about 3-4 millions years ago (during parts of the Pliocene). The mild conditions ended abruptly by rapid ice-sheet growth and development of the very cold, dry climate that now characterizes this region. A contrasting view, based on substantial geologic evidence, suggests that East Antarctica has been cold and the ice sheet stable for at least 8 million years, and perhaps considerably longer. These views lead to drastically different interpretations of the stability of Earth's climate. This project will contribute to a resolution of this important dilemma by introducing independent new evidence and insights der ived from studies of the stability of ground ice and land surfaces in the Dry Valleys, Antarctica. This project will study modern day processes that have important implications for understanding the occurrence of buried ice found recently in Beacon Valley. This ice may be the oldest ice on Earth and, if so, provides strong evidence of long-term stability of the East Antarctic ice sheet and may provide a rare glimpse at atmospheric conditions millions of years ago. Specific processes to be investigated include: energy exchange at the ground surface that affect ground temperature, water vapor transport and other processes leading to the formation or loss of ice in the soil, and frost cracking due to contraction during rapid cooling of the frozen ground in the winter and its resulting disruptions of the soil.