We’ve all heard it before. Tree rings can tell us the age of a tree, but did you know they can also tell us the weather?
How to prep for research
There are a couple of things to consider before scientists survey trees.
First, they must find a site where humans haven’t affected the area with logging or other research.
Then they pick a group of the same species of trees to take samples from. Having numerous samples from the same area can provide a more reliable look at climate similarities over the years.
Christine Buhl, a forest health specialist for the Oregon Department of Forestry, uses an increment borer to core a dead western red cedar at Magness Memorial Tree Farm in Sherwood, Ore., Wednesday, Oct. 11, 2023. (AP Photo/Amanda Loman)
How scientists take samples
Much like coring an apple, scientists core the trees with an instrument called an increment borer.
This allows them to take a thin sample that shows the rings from the outside to the center of the tree.
This method does not harm the tree, and the tree can heal quickly after it’s cored.
After coring the tree, the National Oceanic and Atmospheric Administration (NOAA) says that the scientists return to the lab, sand the samples so every ring is perfectly visible, and place them upright for a microscope to begin research.
What the rings tell us
Counting the rings on the sample can tell us the trees’ age, but it can also tell us what weather patterns were like each year.
NOAA explains, “trees will have narrow rings during cold periods and wider rings for warm periods.”
They also say “trees that depend heavily on moisture during the growing season will have wider rings during rainy periods and narrower rings during dry periods.”
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How this helps us
Studying tree rings can help scientists determine what climate was like for each year the tree was alive.
Because trees can live for hundreds to thousands of years, we can see what the climate was like well before record-keeping began for most in the 1800s.
Determining climate through tree rings over the past thousands of years can help reveal weather patterns and predict what climate we might see in the future.
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