Atlantic to Urals - the Holocene climatic record of Mid-Latitude Europe
Atlantic to Urals - the Holocene climatic record of Mid-Latitude Europe
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大西洋到乌拉尔 - 欧洲中纬度地区的全新世气候记录
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发表时间：
2004
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影响因子：
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通讯作者：
A. Lotter
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作者：
K. Barber;B. Zolitschka;P. Tarasov;A. Lotter
欧洲的中纬度带，大致在北纬45度至65度之间，可能是PEPIII样带中研究最深入的区域，但在这一广阔而多变的区域提供全新世气候变化的综合并不容易。海洋和冰芯记录为大陆上发生的变化提供了一个背景尺度，但这些记录中末次冰期的巨大事件往往掩盖了全新世波动的重要性。在冰芯记录中，1-2℃的温度变化可能表现为微小的变化，但这种变化对冰川、湖泊、树木线和沼泽以及人类都有影响。对人类的直接影响被社会的适应性所缓和，但肯定有一些影响，特别是对农业。本文首先概述了这些记录的性质，包括它们的时空分辨率和气候信号的清晰度等问题。我们试图通过突出来自具有高质量代理记录的关键地点的证据来回答PEPIII科学计划这一部分提出的关键问题，而不是试图综合整个欧洲的情况，这将是不成熟的，需要进一步完善地点年表。欧洲泥炭沼泽地层学是最早的代用气候记录之一，并被用于全新世的细分。最近更多量化分析的发展使泥炭档案重新发挥了作用，似乎沼泽表面湿润的时期最有可能是长期夏季温度下降的反映，因此是蒸发蒸腾的反映，而不是降水记录特征的不规则和快速变化。西欧沼泽在大约8200 - 7800、4400 - 4000、2800 - 2200、1400 - 1300和1100 - 1000 cal. BP发生显著的湿移。在上面的泥炭层仍然存在的地方，小冰河期的两个阶段通常非常明显，即公元1300年至1500年，尤其是公元1650年至1800年。大约1100年、600年和200年的周期已经被确认。这些泥炭数据构成了有价值的低地变化记录，它们对气候强迫的反应非常敏感，而现有的森林却没有这种反应。主要遗址包括爱尔兰的蒙根沼泽；英国的博尔顿·菲尔·莫斯和沃尔顿·莫斯，德国的多森摩尔。在德国北部海岸以东和以南更远的地方，记录变得不那么敏感，只对主要的气候恶化做出反应。湖泊沉积物记录是有价值的数据来源，特别是在沉积物层状的地方。德国西部的Holzmaar湖提供了一个多代理的日历年湖泊记录，可以与其他精确日期的湖泊和其他代理数据进行比较。例如，来自瑞典南部Bussjosjon的数据与Holzmaar的数据比较良好，显示了同步的全新世早期变化，环境条件在10,000 cal. BP左右稳定，以及后来在2700 cal. BP左右人为/气候引起的侵蚀过程增加。然而，Holzmaar对8200年的事件没有反应，因为封闭的落叶林起到缓冲作用，阻止了侵蚀和沉积物转移的增加。欧洲阿尔卑斯山的冰川和森林植被是许多气候变化研究的来源。在全新世开始时，大多数阿尔卑斯冰川退缩到历史尺度，在9400 - 3300 BP之间，瑞士阿尔卑斯东部没有冰川。新冰川作用开始于3300 BP左右，在小冰期达到最大程度，在所有8次同步高山冰推进中，都被探测到并解释为1°C温度下降的结果，其周期为1000年。这些数据与北大西洋冰筏碎片（IRD）事件和Holzmaar沉积速率记录非常吻合。树带界线代表了阿尔卑斯山对气候变化作出反应的主要过渡带，最近的研究强调需要使用花粉和宏观化石分析相结合的方法来确定年代，并与高山和亚高山地区的其他代用物进行比较，例如介形类阀和湖泊水位变化的氧同位素分析。8200 cal. BP事件反映在高寒地区的各种代用记录中，树线研究表明全新世夏季温度波动幅度在±0.5 ~ 1°C之间。欧洲花粉数据库以欧洲中纬度地区为代表，在5W-60°E和45-60°N之间有300个测点，但测点数量和数据质量在该区域的东西部分有所不同，在25°E以东的地区只有10 - 20个测年时间较差的测点。对全新世气候进行了一些定量重建，得到了7月和1月的平均气温和年降水量曲线，以及最近对6000 BP的气候模式的重建，但覆盖范围和年代学的问题限制了我们进行精确的区域间相关性和讨论短期气候事件的能力。洞穴主题提供了年代准确的多代理记录。在挪威、爱尔兰和苏格兰等大西洋主要地点取得的成果的基础上，未来的研究在阐明经向样带上的气候变化和回答涉及大西洋东部影响范围的关键问题方面具有很大的潜力。同样，树木年轮档案代表了有价值的高频率、日历日期的代用气候记录，但它们在中纬度样带的数量很少。很明显，大西洋的变化可以在欧洲大陆的气候中检测到，无论是在个别事件中，如8200 cal.BP，还是在可能反映IRD事件和温盐环流变化的变化周期中。我们越来越认识到太阳活动的变化也有影响。中世纪暖期和小冰期在许多不同的代用记录中得到了很好的表达和确定的年代。未来的研究需要通过更精确的时间控制，以及改进和标准化方法，将来自关键地点的高质量数据连接起来，这两项任务都是新的ESF-HOLIVAR项目的任务。
The mid-latitude belt of Europe, broadly between 45o and 65o N, is probably the most intensively studied area of the PEPIII transect, but providing a synthesis of Holocene climatic change over this large and varied area is not easy. Ocean and ice core records provide a background scale of change to what was happening on the continent, but the tremendous events of the last glacial in these records have tended to obscure the importance of Holocene fluctuations. Temperature variations in the order of 1-2°C may appear as minor variations in an ice core record but such changes had effects on glaciers, lakes, treelines and bogs, and on people. The direct effects on humanity are moderated by the adaptability of societies, but there must have been some impact, especially on farming. In this paper we outline firstly the nature of the records, including such issues as their spatial and temporal resolution and the clarity of the climatic signal. We attempt to answer the key questions posed in this part of the PEPIII Science Plan by highlighting the evidence from key sites with high quality proxy records, rather than attempting to synthesize a Europe-wide picture, which would be premature, and needs further refinement of site chronologies. The stratigraphy of European peat bogs was one of the first proxy climate records, and was used in sub-dividing the Holocene. Recent development of more quantified analyses has revived the usefulness of the peat archive, and it seems that periods of wetter bog surfaces are most probably a reflection of secular summer temperature declines, and therefore evapotranspiration, rather than the irregular and rapid changes that characterise the precipitation record. Significant wet shifts occur in western European bogs at around 8200 - 7800, 4400 - 4000, 2800 - 2200, 1400 - 1300, and 1100 - 1000 cal. BP. Where the upper peat still exists the two phases of the Little Ice Age are often very marked, between AD 1300 - 1500 and especially AD 1650 - 1800. Periodicities of c. 1100, 600 and 200 years have been recognised. These peat data constitute valuable lowland records of change, reacting sensitively to climatic forcing in a way that established forests did not. Key sites include Mongan Bog, Ireland; Bolton Fell Moss and Walton Moss, England, and Dosenmoor, Germany. Further east and south than the north German coast the records become less sensitive, only reacting to major climatic deteriorations. Lake sediment records are valuable data sources, especially where the sediments are laminated. Lake Holzmaar, in western Germany, has provided a multi-proxy calendar-year dated lacustrine record which can be compared both with other precisely-dated lakes and with other proxy data. For example, data from Bussjosjon, southern Sweden, compare well with Holzmaar, showing synchronous early Holocene changes, stabilisation of environmental conditions around 10,000 cal. BP, and later anthropogenic/climate-induced increases of erosional processes around 2700 cal. BP. However, at Holzmaar there is no response to the 8200 year event because the closed deciduous forests operated as a buffer precluding increased erosion and sediment transfer. The glaciers and forest vegetation of the European Alps have been the source of many studies of climatic change. At the onset of the Holocene most Alpine glaciers retreated to historical dimensions, and it has been suggested that in the Eastern Swiss Alps there were no glaciers between 9400 and 3300 BP. Neoglaciation began around 3300 BP, reaching its maximum extent during the Little Ice Age, and in all eight synchronous Alpine ice advances have been detected and interpreted as the result of a 1°C temperature depression having a 1000-year periodicity. These data agree very well with North Atlantic Ice Rafted Debris (IRD) events and with the Holzmaar sedimentation rate record. The timberline represents the major ecotone in the Alps that reacts to climatic change, and recent research has emphasised the need for well-dated sites using pollen and macrofossil analyses in combination, as well as comparisons with other proxies in the Alpine and sub-Alpine region, such as oxygen isotope analyses of ostracode valves and lake level changes. The 8200 cal. BP event is reflected in various proxy records from the Alpine region and treeline studies indicate that Holocene summer temperature fluctuations had an amplitude of between ±0.5 to 1°C. Mid-latitude Europe is well represented in the European Pollen Database, with the zone between 5W-60°E and 45-60°N being characterized by 300 sites, but the number of sites and the data quality varies between the western and eastern part of this zone - the region east of 25°E has only 10 to 20 poorly dated sites. Several quantitative reconstructions of Holocene climate have been made, deriving curves of mean July and January temperatures and annual precipitation, as well as a recent reconstruction of climate patterns at 6000 BP, but the problems of coverage and chronology limits our ability to do precise interregional correlations and to discuss short-term climate events. Speleothems provide well-dated, precise multi-proxy records. Building upon the results from key Atlantic sites in Norway, Ireland and Scotland, future research has great potential to elucidate climatic change on meridional transects and to answer key questions involving the eastern extent of the influence of the Atlantic Ocean. Similarly, tree ring archives represent valuable high frequency, calendar dated proxy climate records, but they are few in number across the mid-latitude transect. It is clear that changes in the Atlantic Ocean can be detected in the climate over the European landmass, both in individual events such as that at 8200 cal.BP, and in cycles of change that may reflect IRD events and changes in the thermohaline circulation. Increasingly we are recognising that changes in solar activity have also had an impact. The Medieval Warm Period and the Little Ice Age are well expressed and well dated in a number of different proxy records. Future research needs to move to linking high quality data from key sites through more precise time control, as well as refining and standardising methods, both tasks for the new ESF-HOLIVAR programme.