NASA has a new online post which describes how trees are able to capture climate information in their annual growth rings. This information, called paleodata or proxy data, allows us to look back farther in time than using just instrumental records. You can use not only living trees but also trees from the past that have been preserved underwater, are incorporated into furniture and buildings, and are hidden under glaciers to build timelines hundreds of years old. You can read about it at https://climate.nasa.gov/news/2540/tree-rings-provide-snapshots-of-earths-past-climate/.
