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

该奖项由国家科学基金会极地项目办公室提供，支持一个研究南极洲干谷地区景观和土壤特征的项目，以更全面地了解过去的气候和环境条件。 气候的动态性越来越受到公众的关注，因为最近出现了一些看似极端的天气事件，人们对气候变暖的担忧也越来越大。厄尔尼诺和全球温室效应已经成为新闻中熟悉的话题。 在这种情况下，了解地球气候的固有可变性以及人类如何影响地球环境变得越来越重要。 提高我们对地球气候系统的理解的一个重要手段是把地球当作一个天然的实验室，并检查它过去的行为。 在过去的几百万年里，地球气候系统中最极端的变化之一是从上新世的温暖时期过渡到冰河时代。 在南极洲，这段时间被认为是相对温和的条件迅速让位于强烈的冰川条件，催化了地球上最大冰盖的生长。这一推论是基于过去气候的地质指标，一些科学家认为，东南极洲相对温暖，大约在3-4百万年前（上新世的部分时间）基本上没有冰川。由于冰盖的迅速增长和现在该地区特有的非常寒冷、干燥的气候的发展，温和的条件突然结束了。一种基于大量地质证据的对比观点认为，南极洲东部一直很冷，冰盖稳定至少800万年，也许更长。这些观点导致了对地球气候稳定性的截然不同的解释。 该项目将通过介绍对南极洲干谷地冰和陆地表面稳定性的研究所得出的独立的新证据和见解，为解决这一重大难题作出贡献。 该项目将研究现代过程，这些过程对理解最近在比肯谷发现的埋藏冰的发生具有重要意义。 这些冰可能是地球上最古老的冰，如果是这样的话，就为东南极冰盖的长期稳定性提供了强有力的证据，并可能提供数百万年前大气条件的罕见一瞥。需要研究的具体过程包括：影响地面温度的地表能量交换、水蒸气输送和导致土壤中冰的形成或损失的其他过程，以及冬季冻土快速冷却过程中收缩引起的冻裂及其对土壤的破坏。

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.