Climate dynamics of the last Millennium derived from cell structure measurements of pine and oak trees in the temperate lowlands of NE-Germany and N-Poland

根据政府间气候变化专门委员会（气候专委会）的评估报告，全球变暖无疑正在发生。此外，区域和季节性气候变化的动态将有很大不同。模式比较表明，地球仪的某些部分和某些季节的温度稳定，在某些情况下甚至下降。为了更全面地了解这些特定的区域和季节趋势，古气候学将其注意力转向长期气候重建。基于树木年轮的温度重建构成了IPCC报告所用数据库的主要部分。到目前为止，温度重建表明，在过去几十年中，温度上升。然而，一个主要的批评是，所使用的大部分树木年轮年表来自纬度或海拔界限附近的树木，例如，阿尔卑斯地区和斯堪的纳维亚半岛的北方。这对于所有超过500年的树木年轮年表来说尤其如此。相比之下，来自树木生长在其纬度或海拔范围内的长期重建缺失。因此，它们不是IPCC数据库的一部分，我们认为这是古气候数据库中的一个关键空白。例如，在欧洲的温带低地，还没有千年尺度的基于树木年轮的温度重建。然而，初步研究表明，这种重建可能会揭示长期的趋势，大大不同于高纬度和高海拔地区获得的，从而留下疑问的大半球和全球重建有关欧洲温带低地的代表性。直到今天，数据库中的这一差距仍然存在，因为温带低地地区的树木气候学一直受到三个主要原因的干扰，即，分散的气候增长关系，只有短年表，因为长寿的树木是罕见的，由于短样本段长度的低频信号的潜在损失。这个难题可以通过分析树木年轮参数而不是宽度来解决，例如，稳定同位素或细胞结构，但测量这些参数非常耗时。最近，我们已经开发出一种新的方法，应用共聚焦激光扫描显微镜，减少了努力获得年表的细胞结构测量。初步分析表明，这些年表包含了强烈的气候信号，表明欧洲温带低地气候重建的巨大潜力。因此，该项目的核心目标是为德国东北部和波兰北部开发细胞结构测量的数百年年表，这些年表将用于长期重建。随后的分析将研究气候动力学和基本模式，例如通过气候模拟研究北大西洋涛动。

According to the assessment report of the Intergovernmental Panel on Climate Change (IPCC) global warming is undoubtedly occurring. Moreover the dynamics of regional and seasonal climate changes will differ significantly. Model comparisons indicate that some parts of the globe and some seasons experience stable or in some cases even declining temperatures. In order to more comprehensively understand such particular regional and seasonal trends, palaeoclimatology directs its attention towards long-term climate reconstructions. Tree-ring based temperature reconstructions form the major part of the data base used for the IPCC report. Temperature reconstructions so far indicated a rise in temperatures during the last decades. One major criticism, however, is that the bulk of the tree-ring chronologies used were from trees growing near the latitudinal or altitudinal limits, e.g., Alpine regions and northern Scandinavia. This is especially true for all tree-ring chronologies longer than 500 years. In contrast, long-term reconstructions derived from trees growing well within their latitudinal or altitudinal limits are missing. Thus they are not part of the IPCC data base, which we believe is a crucial gap in the palaeoclimate database. For instance, no tree-ring-based temperature reconstructions of millennial scale are available as yet for the temperate lowlands in Europe. Preliminary studies, however, indicate that such reconstructions may reveal long-term trends that substantially differ from those obtained for the high latitudes and altitudes, thus leaving doubts concerning the representativeness of large hemispherical and global reconstructions concerning the temperate lowlands in Europe. This gap in the data base still exists until today because dendroclimatology at temperate lowland sites has been upset for three main reasons, i.e., diffuse climate-growth relationships, only short chronologies because long-living trees were rare and the potential loss of low-frequency signals due to short sample segment lengths. This dilemma can be solved by analysing tree-ring parameters, other than width, e.g., stable isotopes or cell structures, but measuring these parameters is very time-consuming. Recently, we have developed a new method applying confocal laser scanning microscopy which reduces the efforts for obtaining chronologies of cell-structure measurements. First analyses have shown that such chronologies contain strong climate signals indicating the great potential for climate reconstructions for the temperate lowlands in Europe. Therefore, the core objective of this project is to develop multi-centennial chronologies of cell-structure measurements for NE-Germany and N-Poland, which will be utilized for long-term reconstructions. Subsequent analyses will examine the climate dynamics and underlying modes, such as the North Atlantic Oscillation by means of climate simulations.