carbon-14 levels in tree rings tagged posts

Picture of the bristlecone pine forest in California, the United States where the bristlecone pine sample for this study used to live (taken by Prof. A.J.T. Jull). In this forest, there are many living old trees exceed 1000 years old. Harsh environments make bristlecone pines very dense and long lives. Credit: A.J.T.Jull

Analysis of tree rings reveals highly abnormal solar activity in the mid-Holocene. An international team led by researchers at Nagoya University, along with US and Swiss colleagues, has identified a new type of solar event and dated it to the year 5480 BC; they did this by measuring carbon-14 levels in tree rings, which reflect the effects of cosmic radiation on the atmosphere at the time...