Abstract
Have you ever wondered how old a big tree is, or counted the rings in a tree stump to discover a tree’s age? Why do the rings tell us about a tree’s age anyway? Trees grow taller and fatter using special cells called meristems, located at the tip of every branch and around their stems under the bark. This special way of growing means that many trees have growth rings that we can count and measure to find out how old they are and how fast they are growing. Scientists are concerned that climate change is changing how fast trees grow and even how long they can live. They have found that many trees are growing slower than they did a few decades ago. When trees grow slower, they absorb less carbon dioxide from the air. This can cause climate change to speed up, making it even worse for trees.