Effects of acidification and warming on long-term ocean carbon cycling constrained by observations

与海洋酸化相关的化学变化将使重要的海洋物种（如颗石藻、有孔虫和翼足类动物）更难构建其碳酸钙（CaCO 3）身体部位，现有的CaCO 3将更容易溶解。因此，酸化可能会减少未来海洋中CaCO 3的产生。另一方面，较高的温度会导致更快的代谢率，这可能会增加初级和CaCO 3的产量。表层沃茨比深层沃茨升温更快，导致分层增加，进入阳光照射的表层海洋（透光区）的营养物质减少。这可能会导致浮游生物种类组成的变化，有利于颗石藻，从而增加碳酸钙的生产。由于CaCO 3与有机颗粒的聚集和缔合，CaCO 3产量的任何变化也可能影响从表层到深海的有机碳通量。这项研究使用一个经过现有观测校准的改进模型，在长时间尺度（数百到数千年）上研究了这些影响对未来全球碳酸钙生产和碳循环的相对重要性。CaCO 3的产生增加了大气中的CO2，因此其未来的演变可能是对气候的重要反馈。将评估这种反馈的符号和不确定性。通过增加基于过程的颗粒聚集和下沉公式，将改进适合千年时间尺度模拟的海洋地球化学循环的现有全球模式。该模型将考虑两种矿物形式的碳酸钙，方解石和文石，以及蛋白石，陆源物质和有机物质作为组件的聚集。将通过分析和校准大体积过滤测量、瓶、透射计和卫星数据（包括误差估计）来创建颗粒有机碳（POC）的全球数据集。这一数据集，连同大量现有的其他全球尺度生物地球化学观测，将用于校准模型和估计不确定的参数，以及不同的结构配方（a）海洋酸化对碳酸钙的生产和（B）颗粒聚集的影响。贝叶斯数据同化计划，旨在量化三个假设的机制，关于控制的雨比（CaCO 3在POC出口从透光层），将被应用。将进行概率预测，以量化每种机制对长期海洋碳循环的影响及其对大气CO2浓度的反馈。将对现有观测约束预测的能力进行评价。该项目旨在更好地，更定量地了解控制海洋中CaCO 3和碳的全球循环及其耦合的多变量过程。在广泛使用的中等复杂性地球系统模式中改进海洋生物地球化学循环将加强研究和教育的基础设施。改进后的模型将公开提供，并有利于长期碳循环过程的未来研究，如人类活动影响或古气候的研究。全球POC数据集也将公开提供。将为K-12教育工作者组织一个为期3天的讲习班，以气候变化和海洋酸化为主要议题。通过更好地评估人为碳排放对海洋生态地球化学循环的影响（包括不确定性），社会可从该项目的成果中受益。

The chemical changes associated with ocean acidification will make it more difficult for important marine species (such as coccolithophores, foraminifera, and pteropods) to build their calcium carbonate (CaCO3) body parts, and existing CaCO3 will dissolve more easily. Thus acidification will likely decrease the production of CaCO3 in the future ocean. Warmer temperatures, on the other hand, lead to faster metabolic rates, which will likely increase primary and CaCO3 production. Faster warming of surface waters than deeper waters leads to increased stratification and less nutrient input into the sunlit surface ocean (photic zone). This may cause shifts in plankton species composition favoring coccolithophores and thus increasing CaCO3 production. Any change in CaCO3 production may also affect organic carbon fluxes from the surface to the deep ocean due to the aggregation and association of CaCO3 with organic particles. This research examines the relative importance of these effects on future global CaCO3 production and carbon cycling on long time scales (hundreds to thousands of years) using an improved model calibrated with existing observations. CaCO3 production increases atmospheric CO2, thus its future evolution may be an important feedback on climate. The sign and uncertainty of this feedback will be evaluated.An existing global model of ocean biogeochemical cycles suitable for millennial time scale simulations will be improved by adding a process based formulation of particle aggregation and sinking. The model will consider two mineral forms of CaCO3, calcite and aragonite, as well as opal, terrigenous, and organic matter as components of the aggregates. A global dataset of particulate organic carbon (POC) will be created by analyzing and calibrating large volume filtration measurements, bottle, transmissometer and satellite data including error estimates. This dataset, together with a large array of existing other global-scale biogeochemical observations will be used to calibrate the model and estimate uncertain parameters as well as different structural formulations of (a) the effect of ocean acidification on the production of CaCO3 and (b) particle aggregation. A Bayesian data assimilation scheme, designed to quantify three hypothetic mechanisms regarding the control of the rain ratio (CaCO3 over POC export from the euphotic zone), will be applied. Probabilistic projections will be carried out to quantify the effect of each mechanism on long term ocean carbon cycling and its feedback on atmospheric CO2 concentrations. The ability of the existing observations to constrain the projections will be evaluated. The project aims to lead to a better, more quantitative understanding of multi-variable processes that control global cycling of CaCO3 and carbon in the ocean and their coupling. Improving ocean biogeochemical cycling in a widely used Earth System Model of intermediate complexity will enhance infrastructure for research and education. The improved model will be made publicly available and benefit future research of long-term carbon cycle processes such as studies of anthropogenic effects or paleoclimate. The global POC dataset will also be made publicly available. A 3-day workshop for K-12 educators will be organized with climate change and ocean acidification as its main topics. Society may benefit from the outcome of this project through an improved assessment (including uncertainties) of the effects of anthropogenic carbon emissions on ocean biogeochemical cycles.