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Science Nation: Lord Of The Tree Rings

3 minutes

(Describer) Streams of light collide to create a globe filled with water. Title: Science Nation. A man looks through a microscope with planks of wood nearby.

(male narrator) You might call him "Lord of the rings." The Tree-Ring Lab is hands-on, so we encourage everybody to touch these pieces of wood. This is a cross-section of a redwood tree.

(narrator) David Stahle is an dendrochronologist at the University of Arkansas. The annual growth rings in trees are a natural archive of environmental history. The time series history of fat and skinny rings is telling you the history of wet and dry years. This is a piece of African bloodwood. This was found in western Zimbabwe.

(Describer) Its rings are thin and dark brown.

(narrator) Long before high-tech weather instruments, nature has kept precise records of rain, drought, even fires.

(Stahle) The climate history encoded in the annual rings of trees is unique. It's like fingerprinting.

(narrator) With support from the National Science Foundation, Stahle is helping Mexico prepare for future droughts by studying how trees responded to severe drought in the past. That will help improve predictions about how future droughts will impact the ecosystem, and could help the country prepare for future water and energy needs.

(Stahle) One notion is that this 21st century drought may be being aggravated by human activity, both at the global scale and at the regional scale due to land-surface changes.

(narrator) Deciphering tree rings can help historians solve mysteries like the fate of the New World's lost colony of Roanoke. Could drought have been a factor? This is a piece of bald cypress from Blackwater River, Virginia.

(Describer) He points out rings.

That is the most severe drought of 800 years in this part of the United States. And that's a significant year because of the disappearance of Virginia Dare and the other colonists at the Roanoke colony in North Carolina. This is a Swedish increment borer. With this, we can extract a core sample without seriously harming the tree.

(narrator) In the field, Stahle's team targets old growth forests with the least imprint of human activity.

(Stahle) These are stupendous trees. They are so precious.

(narrator) And that's a ringing endorsement from this lord of the rings.

(Describer) The globe turns.

For Science Nation, I'm Miles O' Brien.

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David Stahle travels to ancient forests around the world, collecting tree rings to learn more about major climate and historical events dating back hundreds and thousands of years. With help from the National Science Foundation, he uses dendrochronology, or tree-ring dating, to get a snapshot of climate change over time. Stahle runs the Tree-ring Lab at the University of Arkansas, where he and fellow tree-ring researchers are learning that a trend of global warming began in the 1800s and continues today, brought about by changes in tropical sea surface temperatures of no more than a few tenths of a degree Celsius. Today Stahle is working with hydrologists and government planners in California and throughout Mexico to plan for drought and climate change events.

Media Details

Runtime: 3 minutes

Science Nation
Episode 1
4 minutes
Grade Level: 7 - 12
Science Nation
Episode 2
4 minutes
Grade Level: 7 - 12
Science Nation
Episode 3
4 minutes
Grade Level: 7 - 12
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Episode 4
4 minutes
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Episode 5
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Episode 6
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Episode 7
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Episode 8
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Episode 9
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Episode 10
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