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.

大约1400万年前，南极冰盖在中新世中部完全建立。尚不知道为什么冰盖在此时生长，尽管人们认为冰盖扩张发生在“适合和开始”，超过2到300万年。此时间间隔被称为中新世中期气候过渡。地球化学记录表明，气候过渡后的大气二氧化碳水平并没有明显低于以前。但是，这并不一定意味着这种重要的温室气体在地球历史上这个关键时期不会影响气候。确实，海洋中碳的同位素组成的很大变化表明，与气候过渡中冰盖快速生长的间隔有关的全球碳循环发生了很大变化。该提案旨在确定与冰盖生长和衰减相关的气候过渡中二氧化碳的水平是否发生了变化。我们将构建二氧化碳趋势（即增加/降低二氧化碳）和海面温度的记录。我们还将从不同地点生成详细的地层，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过渡的第一个真正整合的记录。这将提供有关建立南极冰盖的原因和影响的宝贵信息。记录应阐明气候过渡的不稳定性。长期的气候转变似乎是由于气候改善和脱气的间隔而打断的。在此类时间间隔内运行的过程与我们对现代南极冰盖的理解及其在未来的全球变暖场景下的行为有直接相关。