You may have heard or read about the lengthy drought that has been impacting the western US over the last decade or two. Since written records only go back into the 1800s, scientists use tree rings to provide proxy data that can help identify when rainfall was scant, since trees don’t grow much in a drought. That allows them to look back much farther in time. This article from Sapiens describes how the scientists analyze the tree rings and what it says about the future of California agriculture.
