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Holocene palaeoclimates of Hokkaido: developing a temporal moisture balance model from raised peat for comparison with equivalent Atlantic records.

北海道全新世古气候：利用凸起的泥炭开发时间水分平衡模型，以便与同等的大西洋记录进行比较。

基本信息

批准号：
NE/D006899/1
负责人：
Paul Hughes
金额：
$ 7.48万
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：
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%2FD006899%2F1
关键词：
Holocene palaeoclimates Hokkaido developing temporal

项目摘要

Extensive studies in the North Atlantic Ocean and on land in Europe and Eastern Canada have shown that past climates have varied on a millennial-scale cycle in those regions. Recent studies of sediment cores from the East China Sea suggest that a similar pattern of ocean current and climate variability is visible in the western Pacific. However, the existence of parallel Pacific-Atlantic climatic events over the last 10,000 years requires more rigorous and wider testing, in particular using equivalent well-dated records of climate change in both regions. This proposal aims to establish a record of past climate change from raised peat bogs on Hokkaido Island, northern Japan, to complement the many European and Canadian peat-based records of past climate change, so enabling a comparison of the records between the two ocean basins. The new Hokkaido records will be the first of their kind in Japan, therefore this proposal will act as a proof-of-concept for the use of Japanese raised bogs in research into past climate change, using watertable reconstruction. By comparing Japanese raised bog climate records with equivalent European and North American records a fair and relatively straightforward comparison of the differences and similarities between the past climates of the North Atlantic and western Pacific can be achieved since all of the records will be responding to similar climatic parameters. This proposal aims to test the hypotheses that (1) the climate of northern Japan has a cyclic behaviour including a millennial pacing immediately driven by changes in the East Asian Monsoon and/or the strength of the Kuroshio Current and that (2) the timings of millennial-scale events are synchronous with those recorded in the North Atlantic region. Raised bogs are already well known sources of records for past climatic change in Europe. Pioneering research in Britain and Denmark has demonstrated that there is a close link between bog watertable levels and changes in air temperature/precipitation. This link exists because raised bogs are gently domed so that the plants living on them receive all of their water and nutrients from the atmosphere. As soon as the balance between rainfall and evaporation changes this shift is reflected in the bog water level. Records of past watertable positions and therefore climate change are preserved in peat bogs because they continuously accumulate peat over time. The peat is composed of the dead remains of plants and animals that once inhabited the bog surface. As climate and the bog watertables change through time the composition of the plant and animal communities living on the bog will shift to reflect the prevailing bog surface wetness and this in turn determines the type of peat that is deposited. Past watertable levels are reconstructed by studying (1) the plant and (2) animal remains in peat as well as (3) the level of breakdown of the peat. The proposed project will employ all three measures of bog surface wetness. The measures will be combined to produce a single, high resolution reconstruction of change in the water balance over the last 7000 years. The project demands a high standard of dating control to enable meaningful comparisons with events from other regions; therefore the project will use both AMS radiocarbon dating and the analysis of volcanic ash layers to construct an age-depth model for the study site. Japan is an active volcanic region and numerous ash layers exist in bogs, lakes and ocean sediments across the region. These ash layers have been geochemically characterised and dated to a high standard by Japanese researchers in recent years. The raised bog moisture balance record will be compared to existing local and regional palaeoclimate records (e.g. lake-level data, loess sequences from China, and speleothems) before comparisons are made with European and North American raised bog records and other 'Atlantic' archives of past climatic change such as the Greenland ice cores.

在北大西洋以及欧洲和加拿大东部的陆地上进行的广泛研究表明，这些地区过去的气候以千年为周期变化。最近对中国东海沉积物岩心的研究表明，西太平洋的洋流和气候变化也有类似的模式。然而，在过去10 000年中，太平洋-大西洋存在着平行的气候事件，这需要进行更严格和更广泛的测试，特别是使用两个区域的气候变化的等效的、日期明确的记录。该提案旨在从日本北方的北海道岛的泥炭沼泽中建立过去气候变化的记录，以补充欧洲和加拿大许多基于泥炭的过去气候变化记录，从而能够比较两个海洋盆地之间的记录。新的北海道记录将是日本第一个此类记录，因此，该提案将作为使用日本提出的沼泽研究过去气候变化的概念验证，使用地下水重建。通过比较日本的沼泽气候记录与欧洲和北美相当的记录，可以实现北大西洋和西太平洋过去气候之间的差异和相似性的公平和相对直接的比较，因为所有的记录将响应类似的气候参数。本提案旨在检验以下假设：（1）日本北方的气候具有周期性行为，包括由东亚季风变化和/或黑潮强度直接驱动的千年一级的步调;（2）千年一级事件的时间与北大西洋地区记录的事件同步。隆起的沼泽已经是欧洲过去气候变化的著名记录来源。英国和丹麦的开创性研究表明，沼泽地下水位与气温/降水量的变化之间存在密切联系。这种联系之所以存在，是因为隆起的沼泽是温和的圆顶状，这样生活在上面的植物就可以从大气中获得所有的水分和养分。一旦降雨量和蒸发量之间的平衡发生变化，这种变化就会反映在沼泽水位上。过去的地下水位位置和气候变化的记录保存在泥炭沼泽中，因为它们随着时间的推移不断积累泥炭。泥炭是由曾经居住在沼泽表面的植物和动物的尸体组成的。随着气候和沼泽地下水位的变化，生活在沼泽上的植物和动物群落的组成将改变，以反映普遍的沼泽表面湿度，这反过来又决定了沉积的泥炭类型。通过研究（1）泥炭中的植物和（2）动物遗骸以及（3）泥炭分解的程度，重建了过去的地下水位。拟议的项目将采用沼泽表面湿度的所有三个措施。这些措施将结合起来，以产生一个单一的，高分辨率的重建变化的水平衡在过去的7000年。该项目需要高标准的测年控制，以便能够与其他地区的事件进行有意义的比较;因此，该项目将使用AMS放射性碳测年和火山灰层分析，为研究地点建立一个年龄-深度模型。日本是一个活跃的火山地区，许多火山灰层存在于整个地区的沼泽，湖泊和海洋沉积物中。近年来，日本研究人员对这些火山灰层进行了高标准的地球化学表征和年代测定。凸起的沼泽水分平衡记录将与现有的当地和区域的古气候记录（例如，湖泊水平数据，来自中国的黄土序列和洞穴沉积物）进行比较，然后与欧洲和北美凸起的沼泽记录和其他“大西洋”过去气候变化的档案，如格陵兰冰芯进行比较。