Testing the amplitude and rapidity of carbonate saturation change and global climate during the high pCO2 Oligocene 'cold house'

测试高 pCO2 渐新世“冷屋”期间碳酸盐饱和度变化和全球气候的幅度和速度

• 批准号: NE/F003641/1
• 负责人: Heiko Pälike
• 金额: $ 33.66万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF003641%2F1
• 关键词: Testing; amplitude; rapidity; carbonate; saturation

The overarching objective of the proposed research is to establish the rapidity and amplitude of variations in ocean acidification during the Oligocene, exploiting the two high-resolution, single site records that have recently been established in the equatorial Pacific by the Ocean Drilling Program, with a view to test recently proposed model hypotheses as to the origin of these fluctuations . Numerous efforts are currently underway to investigate modern changes in atmospheric pCO$_2$, and to decipher their impact on global and local temperature, sea-level, and the hydrological cycle. Yet, pCO$_2$ changes also profoundly affect the Earth System through changes of ocean pH. Indeed, the impacts of ocean acidification are additional to, and may exacerbate, the effects of climate change, as recently established by a working group of the Royal Society (2005). Geological records provide the means to answer some of the key questions that relate to the quantification of the acidification process, and what measures of mitigation might be necessary, in particular: How fast is fossil fuel (or added carbonic acid) neutralised? What is the effect of CaCO$_3$ buffering on oceanic carbonate ion saturation (and in turn atmospheric pCO$_2$)? The large number of feedback components that connect the global carbon cycle, atmospheric pCO$_2$, temperature, dissolved oceanic [CO$_3^{2-}$] and pH need to be constrained by present-day measurements as well as data from the geological archive in order to advance the prediction of timing and amplitude of future changes. Previous reconstructions of CCD and lysocline variations have principally been following two angles of attack: a geochemical approach using boron isotopes and their sensitivity with respect to ocean water pH, or a sedimentological proxy approach, mapping the occurrence and absence of calcium carbonate in sediments. The latter approach generally provides a low-resolution but large regional perspective. Indeed, recent research by the PIs has resulted in the first constraints on a coupling between the lysocline and the onset of the Oligocene ``cold-house'' during a rapid and extensive simultaneous deepening of the CCD of $>$1 km, and a shift in benthic oxygen isotope values towards greater values by more than 1 permille. Here we propose to exploit, in a novel way, an ideal ``natural laboratory'' setting to reconstruct variations in the oceanic lysocline and the effect of these variations on a palaeoclimate proxy (oxygen isotopes) during the Oligocene, as provided by drill sites 1218 and 1219 in the Equatorial Pacific. Both sites record high-resolution climate proxy records for the Oligocene, but with a vertical offset in palaeodepth of about 300 to 500 metres. Current hypotheses predict that this vertical offset should result in a difference in carbonate dissolution affecting both CaCO$_3$ flux, and stable isotope measurements of d13C and d18O in bulk and benthic foraminiferal calcite. Data from these sites will provide the first opportunity to test recently modeled short-term oceanic [CO$_3^{2-}$] (and thus lysocline) variations on glacial-interglacial (kyr) time scales \citep{Palike2006}, within a setting of higher pCO$_2$ ``cold-house'' conditions, and thus provide a more realistic approach as to what future changes in ocean acidification state might entail, and on what time scales natural variability occurs despite the buffering effect of carbonate dissolution at the sea-floor.

拟议研究的首要目标是利用大洋钻探方案最近在赤道太平洋建立的两个高分辨率单点记录，确定渐新世期间海洋酸化变化的速度和幅度，以期检验最近提出的关于这些波动起源的模型假设。许多努力目前正在进行中，以调查现代变化的大气pCO_2 $，并破译其对全球和当地的温度，海平面和水文循环的影响。然而，二氧化碳分压的变化也通过海洋pH值的变化深刻地影响地球系统。事实上，海洋酸化的影响是额外的，并可能加剧，气候变化的影响，最近由皇家学会的一个工作组（2005年）。地质记录提供的手段来回答一些关键的问题，涉及量化的酸化过程，什么样的缓解措施可能是必要的，特别是：有多快是化石燃料（或添加碳酸）中和？CaCO_3缓冲作用对海洋碳酸盐离子饱和度（进而对大气pCO_2）有什么影响？连接全球碳循环、大气pCO 2 $、温度、溶解海洋[CO 3 ^{2-}$]和pH值的大量反馈成分需要受到当前测量以及地质档案数据的约束，以便提前预测未来变化的时间和幅度。以前的重建CCD和溶跃层的变化主要是以下两个角度的攻击：地球化学方法，使用硼同位素和它们的敏感性，相对于海水pH值，或沉积学代理的方法，映射的发生和不存在的碳酸钙沉积物。后一种方法通常提供低分辨率但大的区域视角。事实上，研究所最近的研究已经导致了第一个限制之间的耦合溶跃层和渐新世“冷室”的开始在一个快速和广泛的同时加深的CCD $>$1公里，并在海底氧同位素值向更大的值超过1千分之一的转变。在这里，我们建议利用，在一个新的方式，一个理想的“自然实验室”设置重建海洋溶跃层的变化和这些变化的影响，在渐新世的古气候代理（氧同位素），提供的钻井现场1218和1219在赤道太平洋。这两个地点都记录了渐新世的高分辨率气候代用记录，但在古深度上的垂直偏移约为300至500米。目前的假说预测，这种垂直偏移应导致碳酸盐溶解影响CaCO 3 $通量的差异，并在散装和底栖有孔虫方解石的d13 C和d18 O的稳定同位素测量。来自这些站点的数据将首次提供机会来测试最近模拟的短期海洋[CO$_3^{2-}$]（因此溶跃层）变化的冰川间冰期（kyr）时间尺度\citep{Palike 2006}，在较高的pCO_2 $"冷室“条件的设置，从而提供了一个更现实的方法，以什么样的未来变化，海洋酸化状态可能需要，以及尽管海底碳酸盐溶解有缓冲作用，但在什么时间尺度上发生自然变化。

项目成果

Antarctic ice sheet and oceanographic response to eccentricity forcing during the early Miocene

• DOI: 10.5194/cp-7-869-2011
• 发表时间: 2011-01-01
• 期刊: CLIMATE OF THE PAST
• 影响因子: 4.3
• 作者: Liebrand, D.;Lourens, L. J.;Paelike, H.
• 通讯作者: Paelike, H.

A Cenozoic record of the equatorial Pacific carbonate compensation depth

赤道太平洋碳酸盐补偿深度的新生代记录

• DOI: 10.1038/nature11360
• 发表时间: 2012-08-30
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Paelike, Heiko;Lyle, Mitchell W.;Zeebe, Richard E.
• 通讯作者: Zeebe, Richard E.