Tree rings reveal climate histories

The aim of the project TREE-RINGS & CLIMATE (Temporal instability of tree-ring/climate relationships: Tree responses to climatic change and implications for paleoclimate research) was to provide a greater understanding of the relationship between tree rings and climate. This important issue has potential implications for the global carbon cycle, forest growth patterns and climate change reconstructions.

Project partners evaluated two areas of uncertainty over time found in Boreal and Iberian forests, termed the divergence problem and climate stress strength. New approaches were used to understand and attribute their causes and their implications for climate research.

The first approach used a network of tree-ring chronologies to assess climate change impacts on forests and assess their response to future climate change conditions. Approach two explored stable isotopes as a possible key to the divergence problem. The third approach developed more reliable reconstructions of past climate using tree ring parameters (width, density and stable isotopes) and non-tree-ring archives to reduce uncertainties in climate reconstructions.

Results showed that tree-ring analyses can provide an insight back in time from several centuries to millennia, with a resolution at the annual scale. Project partners analysed different tree ring parameters and applied different statistical techniques to improve tree ring models and growth model predictions.

TREE-RINGS & CLIMATE will advance scientific knowledge on the interactions between the biosphere, ecosystems and human activities. By studying interactions between climate and forests, researchers were able to determine forest responses to a changing climate and extract the climate ꞌsignalꞌ contained in tree rings. The project therefore provided valuable expertise on tree growth and how to reduce uncertainties in the reconstruction of past climate.

The project will help to quantify local impacts of climate change in one of the most sensitive regions of Europe (e.g. Iberian Peninsula) and worldwide (Boreal region), supporting further initiatives. In addition, the work conducted on climate change processes and impacts on natural resources will help to identify and assess key drivers and improve understanding of their interactions.