Tree rings and El Ninos

Tree rings, including bristlecone pines, have been used by climate scientists as a useful took, claiming they show past temperatures. Mike Baillie, a dendrochronologist begs to differ – he has publically said they do not (and others have periodically pointed out that tree rings are affected by a variety of factors, such as precipitation rates, and where individual trees might be situated – within a forest and surrounded by aged trees, or in an open position without any competition) – and so on. In a study that is reported at www.physorg.com/print223893131.html tree rings are used to research rainfall over the last 1000 years and this is thought to reflect El Nino and La Nina episodes, and water temperature in the Pacific Ocean.