Climate Proxies

Students will be introduced to examples of paleoclimate proxies. They will analyze a tree ring proxy to understand that annual light and dark layers represent summer and winter tree growth. In addition, they will interpret a tree ring record to learn that the width and shape of the tree ring is dependent on environmental conditions.


1. Begin the class period by showing the video clip: Why is it important to reconstruct the long history of the Earth's climate, and how can we do that? 

: The video clip is a very large file. You may wish to download the video clip to your computer prior to using it in your classroom.

2. Next, present the Climate Proxy PowerPoint slide show. The Climate Proxy PowerPoint slide show contains 15 slides. It presents an overview of paleoclimatology, provides students with explanations about the importance of studying past climates, presents scientific methods for studying past climates, and provides an overview of climate proxies that are used by scientists who study past climates.

3. Ask students what they can learn from a tree and discuss student responses.

4. Distribute the Tree Ring Exploration Handout to the students.

5. Instruct students to review the Background Information and Activity Description sections on the first page of their handout.

6. Tell students they will examine a tree ring record to explore a tree’s history. Instruct students to turn to the second page of their handout.

7. Display the tree ring record image on the handout to the front of the class. Show students how to interpret the tree ring record image. Emphasize to students that each dark and white layer represents one complete year of growth. The distance between two dark lines represents one annual layer (or one year) of growth. The width of the ring is dependent on the precipitation available to the tree. Trees will produce wider rings during wet and cool years. Tree rings will be narrow during hot and dry (drought) years.

8. Tell students that the outer ring of the tree on their handout grew in 2011.

9. Instruct students to answer questions #1-5 on their Exploration Handout.

Implementation Suggestion: 
- Some lower ability level students might have difficulty interpreting dry spells and rainy spells on the tree ring diagram. You may wish to explicitly model to your students how to examine these areas on the tree ring diagram.

10. Review student responses to the questions on their exploration sheets. Ask students if they have any questions about interpreting past climates with tree ring proxies.

Materials Needed:


Why is it important to reconstruct the long history of the Earth's climate, and how can we do that? (Quicktime Movie) (85.8 MB) Duration 1:20

PowerPoint Slideshow

Climate Proxy PowerPoint



Tree Ring Exploration Teacher Guide (PDF / MS Word)

Tree Ring Exploration Handout (PDF / MS Word)

Assessment Information 

Tree Ring Exploration Assessment (PDF / MS Word)

Supplemental Homework Readings for Students

How are Temperatures on Earth Changing (PDF)

Teacher Resources/Content Support 


Paleoclimatology - Print Version (PDF)