Tree-ring dating and climate reconstruction from wood anatomy
Trees produce one growth ring per year: a light-colored earlywood band formed in spring and a denser latewood band in summer/fall. Ring width encodes climate signal — warm, wet years produce wide rings; drought or cold produces narrow rings. By matching the distinctive pattern of wide and narrow rings between overlapping samples (crossdating), dendrochronologists have built continuous chronologies extending back over 10,000 years using subfossil wood. The Irish oak chronology and Bristlecone pine (Pinus longaeva, up to 5,000 years old) chronologies are used to calibrate radiocarbon dating curves and reconstruct past climate variability.