As part of the terrestrial biosphere, trees are located at an important junction of the water cycle on the Earth’s surface. This junction controls the portioning of precipitation waters into surface or subsurface run-off systems, as well as the return of water to atmospheric moisture by means of evapotranspiration. The temporal dynamics of changes at this junction of the water cycle are documented in the tree-ring stable isotopes. Thus, stable isotope analyses provide information that cannot be found in any other tree-ring proxy such as ring-width or density.

Novel, highly resolved intra-seasonal measurements of stable C & O isotope ratios within tree-rings aim to explore the potential of extracting seasonality signals from the tree-ring archive. This is of great importance, because the main impacts arising from anticipated global warming will not only be caused by changes in inter-annual (year to year) climatic variability and the frequency of extreme events, but also by changes in seasonality.