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ANDRILL (ANtarctic DRILLing Project) is a scientific drilling project in Antarctica gathering information about past periods of global warming and cooling. The project involves scientists from Germany, Italy, New Zealand, and the United States. At two sites in 2006 and 2007, ANDRILL team members drilled through ice, seawater, sediment and rock to a depth over more than 1,200 m and recovered a virtually continuous core record from the present to nearly 20 million years ago. The project is based at McMurdo Station in Antarctica In studying the cores, ANDRILL scientists from various disciplines are gathering detailed information about past periods of global warming and cooling. A major goal of the project is to significantly improve the understanding of Antarctica's impact on the world's oceans currents and the atmosphere by reconstructing the behavior of Antarctic sea-ice, ice-shelves, glaciers and sea currents over tens of millions of years. Initial results imply rapid changes and dramatically different climates at various times on the southernmost continent.〔Quirin Scheirmeier, "Sediment cores reveal Antarctica's warmer past," ''Nature News'', April 24, 2008.〕 The $30 million project has achieved its operational goal of retrieving a continuous core record of the last 17 million years, filling crucial gaps left by previous drilling projects.〔Alexandra Witze, "School of Rock," ''Nature'', v.446, no.7132, p. 129, March 8, 2007.〕 Making use of knowledge gained through prior Antarctic drilling projects, ANDRILL employed novel techniques to reach record depths at its two drilling sites. Among the innovations deployed were a hot-water drilling system that allowed for easier ice-boring and a flexible drill pipe that could accommodate tidal oscillations and strong currents. On December 16, 2006, ANDRILL broke the previous record of set in 2000 by the Ocean Drilling Program's drill ship, the Joides Resolution.〔http://www.scar.org/news/antarctic/2006.html〕 The Antarctic-record of core ANDRILL went on to recover represents geologic time to about 13 million years ago. In 2007, drilling at the Southern McMurdo Sound, ANDRILL scientists recovered another 1138 meters (3733.6 ft) of core. One goal in 2006 was to look at a period of around 3 to 5 million years ago in the Pliocene, which scientists know to be warmer. The team’s sedimentologists identified more than 60 cycles in which ice sheets or glaciers advanced and retreated across McMurdo Sound.〔 ==Objectives of ANDRILL== Scientists on the ANDRILL project seek evidence in their sediment cores to tie together decades of paleoclimate research to get a more complete picture of how the Antarctic ice sheets acted in past times of global warmth. The target, the warmest part of the middle Miocene (between 14 million and 15 million years ago) represents a period when the Earth was much warmer than today. The geological target for 2007-2008 was the past 17 million years of Earth history, including the 4 million-year gap between the earlier projects, especially during the warm middle Miocene period. Geologist David Harwood of the University of Nebraska–Lincoln explains that understanding what happened in the warm period is especially important as Earth's climate continues to warm. In the past, scientists working in different parts of the world noted changes in their data, they often deduced that these must be due to changes in the ice on Antarctica. With this season's drilling scientists will be able to make those connections with more certainty. "If we can identify time periods in Antarctica when we had minimal ice and minimal ocean freezing, we can then look at that particular interval of time - and hopefully several examples from those intervals of time — and see how the rest of the world responded. This will provide evidence to confirm or reject a lot of interpretations that have been suggested and linked to Antarctica," he said. When sea ice forms, it pushes the salt out, creating a mass of cold, salty, dense water that sinks to the bottom of the ocean, creating deep ocean currents that affect ocean circulation and the distribution of heat worldwide.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ANDRILL」の詳細全文を読む スポンサード リンク
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