An Integrated Study of the Middle Miocene Climate Transition.

中中新世气候转变的综合研究。

基本信息

批准号：
NE/D008654/1
负责人：
Caroline Lear
金额：
$ 9.78万
依托单位：
CARDIFF UNIVERSITY
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD008654%2F1
关键词：
Integrated Study Middle Miocene Climate

项目摘要

The East Antarctic ice sheet became fully established in the middle Miocene, about 14 million years ago. It is not known why the ice sheet grew at this time, although it is believed that the ice sheet expansion happened in 'fits and starts', over 2 to 3 million years. This time interval is known as the middle Miocene climate transition. Geochemical records show that levels of atmospheric carbon dioxide were not noticeably lower after the climate transition than before. However, this does not necessarily imply that this important greenhouse gas did not influence the climate at this crucial time in Earth's history. Indeed, large changes in the isotopic composition of carbon in the ocean suggest that there were large changes in the global carbon cycle associated with the intervals of rapid ice sheet growth within the climate transition. This proposal aims to determine whether levels of atmospheric carbon dioxide changed within the climate transition, in association with the bursts of ice sheet growth and decay. We will construct records of carbon dioxide trends (i.e., increasing/decreasing carbon dioxide) and sea surface temperatures. We will also generate detailed stratigraphies from different sites, which will enable us to link these records with other records of ice volume, deep sea temperatures and weathering. This will provide the first truly integrated record of the middle Miocene climate transition. This will provide valuable information on the causes and effects of the establishment of the Antarctic ice sheet. The records should shed light on the erratic nature of the climate transition. The long term climate transition appears to have punctuated by intervals of climatic amelioration and deglaciation. The processes operating during such intervals have direct relevance to our understanding of the modern day Antarctic ice sheet and its behaviour under future global warming scenarios.

南极东部冰盖在中新世中期（大约 1400 万年前）完全形成。目前尚不清楚为什么冰盖此时会增长，但人们相信冰盖的扩张是在两三百万年的时间里“断断续续”发生的。这个时间间隔被称为中新世中期气候转变。地球化学记录显示，气候转变后大气中二氧化碳的含量并没有明显低于气候转变之前。然而，这并不一定意味着这种重要的温室气体在地球历史上的这个关键时刻没有影响气候。事实上，海洋中碳同位素组成的巨大变化表明，全球碳循环发生了巨大变化，与气候转型期间冰盖快速增长的时间间隔相关。该提案旨在确定气候转型期间大气二氧化碳水平是否发生变化，与冰盖生长和腐烂的爆发有关。我们将构建二氧化碳趋势（即二氧化碳增加/减少）和海面温度的记录。我们还将生成来自不同地点的详细地层图，这将使我们能够将这些记录与冰量、深海温度和风化的其他记录联系起来。这将提供中新世中期气候转变的第一个真正完整的记录。这将为了解南极冰盖形成的原因和影响提供有价值的信息。这些记录应该揭示气候转变的不稳定本质。长期的气候转变似乎不时出现气候改善和冰川消融的时期。在这样的时间间隔内运行的过程与我们对现代南极冰盖及其在未来全球变暖情景下的行为的理解直接相关。