PIRE: DUST stimulated drawn-down of atmospheric CO2 as a trigger for Northern Hemisphere Glaciation

PIRE：灰尘刺激大气中二氧化碳的减少，引发北半球冰川作用

• 批准号: 1545859
• 负责人: Carmala Garzione
• 金额: $ 505.06万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-10-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1545859&HistoricalAwards=false
• 关键词: PIRE; DUST; stimulated; drawn; down

Understanding the geologic processes underlying the long-term global cooling over the past 50 million years (myr) is important for understanding the climate conditions on Earth today. The Northern Hemisphere was largely ice-free 4 myr ago followed by an acceleration of global temperature decline at ~3.6 myr ago, with continental ice sheets developing on northern hemisphere continents by ~2.7 myr ago. Limited atmospheric CO2 records suggest a decline in CO2 from ~400 to ~300 parts per million by volume (ppmv) during that time period could have cooled the Earth sufficiently to enable ice sheets to grow. Yet the cause for this decline in CO2 remains unknown. This international research and educational collaboration between 7 U.S. and 3 Chinese institutions will evaluate a new hypothesis: atmospheric dust derived from Central Asian deserts fertilized the North Pacific ocean, stimulating algal productivity, which in turn drew down atmospheric CO2 leading to Northern Hemisphere Glaciation (NHG). Through field work studies in China, laboratory analyses of ocean and terrestrial sedimentary deposits, and atmospheric and ocean modeling studies, the investigators and students will generate and compare a wide range of paleoclimate records from diverse geological archives to evaluate the role of atmospheric dust in CO2 decline and global cooling at the onset of NHG. The findings from this research project may ultimately contribute to knowledge with global policy implications.By evaluating the significance of atmospheric dust in sustaining cool climate conditions on Earth, this study is expected to elucidate the mechanisms of climate cooling in the recent geologic past. Specifically this study will establish records of: 1) the aridification history of Central Asia, northern Tibet, and the Chinese Loess Plateau (CLP) as related to records of deformation and surface uplift in high Asia within and to the west of these regions, 2) wind erosion of Central Asia basins and dust accumulation in the CLP, 3) dust flux, algal productivity, and sea surface temperature in the North Pacific and South Atlantic, and 4) terrestrial CO2 in the interval of 4.5-2.5 Ma. Modeling and sensitivity studies will (1) evaluate the sensitivity of Asian climate and the dust cycle to the growth of topography and to the background global climate; (2) determine the amount of cooling that could result from Pliocene dust transport to the North Pacific; (3) evaluate the potential influence of Asian dust on atmospheric CO2. Through this research program, US graduate students will gain access to research facilities as well as field localities in China that would otherwise be inaccessible and engage in mutually beneficial collaborative research activities with Chinese partners via bilateral visits; US undergraduate students will also have the opportunity to participate in summer schools, workshops, and research projects; the investigators will develop outreach tools for museums to increase public understanding of the role of atmospheric dust in climate change.

了解过去 5000 万年（MYR）长期全球变冷背后的地质过程对于了解当今地球的气候条件非常重要。 4 马来西亚林吉特前，北半球基本无冰，随后约 3.6 马来西亚林吉特前，全球气温加速下降，约 2.7 马来西亚林吉特前，北半球大陆上出现了大陆冰盖。有限的大气二氧化碳记录表明，在此期间二氧化碳体积从约 400 ppmv 下降到约 300 ppmv，可能足以使地球冷却，使冰盖生长。然而二氧化碳浓度下降的原因仍不清楚。这项由 7 个美国和 3 个中国机构之间的国际研究和教育合作将评估一个新假设：中亚沙漠产生的大气尘埃肥沃了北太平洋，刺激了藻类生产力，进而减少了大气中的二氧化碳，导致北半球冰川（NHG） ）。通过在中国的实地工作研究、海洋和陆地沉积物的实验室分析以及大气和海洋模拟研究，研究人员和学生将生成并比较来自不同地质档案的广泛古气候记录，以评估大气尘埃在二氧化碳中的作用NHG 开始时的衰退和全球变冷。 该研究项目的结果可能最终有助于了解具有全球政策影响的知识。通过评估大气尘埃在维持地球凉爽气候条件方面的重要性，这项研究预计将阐明最近地质历史中气候变冷的机制。具体而言，本研究将建立以下记录：1) 中亚、西藏北部和中国黄土高原 (CLP) 的干旱化历史，与这些地区及其西部高亚洲的变形和地表隆起记录相关，2 ) 中亚盆地的风蚀和中亚地区的沙尘积累，3) 北太平洋和南大西洋的沙尘通量、藻类生产力和海面温度，以及 4) 中亚地区的陆地二氧化碳4.5-2.5马。建模和敏感性研究将（1）评估亚洲气候和沙尘循环对地形生长和全球背景气候的敏感性； (2) 确定上新世尘埃输送到北太平洋可能产生的冷却量； (3)评估亚洲沙尘对大气CO2的潜在影响。通过该研究项目，美国研究生将有机会进入中国的研究设施和实地考察地点，并通过双边访问与中国合作伙伴开展互利的合作研究活动；美国本科生还将有机会参加暑期学校、研讨会和研究项目；研究人员将为博物馆开发外展工具，以提高公众对大气尘埃在气候变化中的作用的了解。