Trees are a substantial part of the human environment. As long living plants, tree growth is governed by environmental and climate changes within their habitat. The growth rings of their wood record the temporal dynamics of tree physiological reactions to these changes. Physical and chemical analyses of tree rings provide exactly dated and annually resolved data of environmental and climate variability of the past 14.000 years. The wide distribution of trees over various regions of the world, including those with greatest population densities and also marginal areas allows to gain information about local and regional consequences of global climate change. Tree rings of oak planks from a Neolithic wooden well discovered and excavated near Erkelenz in the Lower Rhine Embayment were analysed for their ratios of carbon and oxygen isotopes (13C/12C, 18O/16O) for the time period 5320 to 5081 BC. The climate reconstruction derived from the tree-ring isotope records revealed that the average air temperature of the vegetation period decreased constantly by ca. 2 °C during a period of 95 years between 5270 to 5175 BC. Furthermore, abrupt temperature
changes of 1.5 to 2 °C within 5 to 10 year periods were reconstructed, which coincided with considerable changes in moisture conditions, especially during the 20 – 30 years prior to the construction of the wooden well.