Tina is a climate scientist. She wants to investigate weather patterns from further back than the last 150 years. What sources can Tina use in her research?

Tina could use dendrochronology in her studies. Dendrochronology is the study of tree rings and scientists use this method to study past climatic conditions. Tree rings record the annual growth of the tree. A smaller than average tree ring indicates a possible drought or other climatic factor than can negatively affect the growth of trees. A larger than average ring can speak of favorable conditions for growth such as increased rainfall.