Erika Wise, associate professor of geography, researches the Earth’s climate — past and present — through dendrochronology, the study of tree rings. She collects samples to determine how old trees are and when droughts and fires may have occurred. Technology enables her to study trees all over the planet to observe climate change patterns and predict future ones. With microscopic inspection, Wise can assign an exact year to each ring.
You can at least get an approximate age by counting the rings. We do a slightly more in-depth process called cross-dating because trees are sometimes tricky and like to put on what we call false rings, or they sometimes miss a ring.
Wise says that although tree rings have played a big part in understanding climate change from centuries ago, most researchers today are motivated by a concern for what could happen in the future.
To be able to say, ‘Is recent climate change different?’ we have to be able to compare it to something, so we need these other tools to be able to know what the past climate was like.
Wise also gathers data from satellite imagery and other sources like the wax on preserved tree leaves, the nests of pack rats and aquatic organisms.
Corals record conditions in the ocean. The sediments in the bottom of the lakes and the oceans are actually recording things like droughts and floods and they have all these tiny little organisms in there that have some sort of climate signal in them.
Every summer, Wise and her students use a special tool to collect straw-sized samples from trees, which fill in the holes with resin and keep growing. It’s easier to take a sample from a tree than, say, a glacier. Trees are really good recorders of climate. They have this great feature called annual resolution, so you can assign an exact calendar year to all those rings back through time. And you know exactly when that ring was grown and you can get that information.
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