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Measuring tree rings

Have you ever noticed that tree stumps have concentric rings inside them? Data about past climate comes in a lot of forms – it ranges from direct information like written records by settlers and explorers to tribal art and folklore hinting at variations in the weather. Other clues lie in nature itself. Those concentric circles in tree stumps that tell us how old a tree is can also tell us whether it survived a drought or suffered a cold winter.

Rings of tree showing growth
There are tons of clues about the history of our planet hidden inside the rings of a tree stump. Illustration courtesy of Science Education Resource Center, Carleton College

One scientist who is hunting for clues about ancient climate is a paleoclimatologist named Kathleen Johnson. Dr. Johnson studies rocks found deep inside the cool darkness of caves, and studies their chemical properties to understand what the Earth was like when those rocks formed. The structures of these slow-growing rocks hide clues about the lifetime of the speleothem, kind of like how you can read tree rings to decipher the climate that trees have experienced over their lifetimes. By peeling back the layers of the slow-growing rock formations, she can trace climate shifts across the millenia.

Read the post on Dr. Johnson's amazing research, and then find a tree stump near your home and follow along with this activity to learn about how climate clues hide all over nature.

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