Tree Rings — Like Reading a Book

Jul 31

Trees have an amazing way of telling the story of Earth's past through their rings. Each ring a tree grows can show scientists a lot about what the climate was like in the past. Here’s how they do it:

Reconstructing Past Climate

Trees act like nature’s record keepers. Every year, they grow a new ring that records information about the climate, like how much rain fell or how warm it was. Scientists study these rings in a field called dendrochronology. By looking at the width, density, and makeup of the rings, they can tell a lot about past climates. For instance, wide rings usually mean the weather was good for growing, like warm and wet years. Narrow rings often mean tougher times, like cold or dry years.

Some trees are thousands of years old, so they give us a long history of the climate. This helps scientists understand how today’s climate compares to the past. For example, tree rings have shown that the severe drought in the Colorado River area right now isn’t the worst ever—there was an even longer drought that lasted 62 years in medieval times.

Identifying Anomalies and Trends

By comparing tree rings from today with those from hundreds or thousands of years ago, scientists can see if current climate changes are normal or if they’re unusual. This can show us if humans are affecting the climate. For example, tree rings from around the world, along with other records like seashells and ice cores, show that the recent warming is unlike anything seen before. This evidence supports the idea that human activities are causing climate change.

Understanding the Impacts of Extreme Events

Tree rings also help scientists learn about extreme weather events like droughts, heatwaves, and volcanic eruptions from the past. By studying these events, researchers can see if human actions are making such events more common or intense. For instance, tree rings revealed that a big volcanic eruption in 1568 caused the Earth to cool for two years. This cooling led to big climate changes that lasted for decades and may have contributed to major events like the decline of the Ottoman Empire, the fall of the Ming Dynasty, and the abandonment of the Jamestown colony in Virginia.

Conclusion

Studying tree rings is a powerful way to learn about Earth’s climate history and see how human activities might be changing it. As scientists keep collecting and studying tree-ring data, we’ll get even better at understanding the complicated ways climate change affects our planet. If you want to learn more, check out our other educational posts!

Live Science | https://www.livescience.com/planet-earth/climate-change/tree-rings-reveal-summer-2023-was-the-hottest-in-2-millennia

NASA | https://climate.nasa.gov/news/2540/tree-rings-provide-snapshots-of-earths-past-climate/

University Corporation for Atmospheric Research |

https://scied.ucar.edu/learning-zone/how-climate-works/tree-rings-and-climate

The New York Times | https://www.nytimes.com/2019/04/30/science/tree-rings-climate.html

NOAA Climate.gov | https://www.climate.gov/news-features/blogs/beyond-data/how-tree-rings-tell-time-and-climate-history

The Harvard Gazette | https://news.harvard.edu/gazette/story/2022/09/harvard-scientists-study-tree-rings-see-climate-change-clues/

National Library of Medicine | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC33752/