Dark Skies: Volcanic Contribution to Climate Change

Main content

A volcanic eruption can affect global climate for several years. In this lesson, students are introduced to how a volcanic eruption affects the atmosphere. Students explore recent and historical images and videos and create a simple model. To learn about atmospheric change that causes a reduction in light to Earth’s surface and how this affects climate.

Learning Objectives

  • Illustrate the effects of a volcanic eruption on the appearance and composition of the atmosphere
  • Recognize that volcanic eruptions, a process of the geosphere, can affect the composition of the atmosphere
  • Investigate the impact of large volcanic eruptions on environments as well as climate
  • Summarize how volcanic eruptions, a natural event, contributes to climate change


For the teacher/class:

For each student:

For each group of 3:

  • Three snack bags
  • 1 box of baking soda
  • 1 regular bottle of white vinegar
  • 1 small bag of flour
  • White copy paper
  • Pencil
  • Flashlights
  • Safety glasses or goggles
  • Permanent marker to mark baggies (or label stickers)
  • Metric ruler


  • Load the websites for the videos and images; practice showing sections that are highly engaging with muted sound.
  • Write on the board or project the questions for the launch. You might also type the questions up for students.
  • Prepare the following materials for the class:
    • Aliquot 100 ml vinegar into small beakers, enough for each group of 3 students to have one beaker
    • Prepare ~3 tsp baking soda sample, one for each group
    • Prepare ~3 tsp flour sample, one for each group.
  • Make copies of, or provide the link to the article, How Volcanoes Influence Climate
  • Make copies of Student Directions: Volcanic Eruption Protocol
  • Make copies of Volcanic Eruption: Sequence of Events. Cut out the squares and put each set together in a paperclip or envelope.
  • Make copies of Volcanic Eruption, Climate Disruption
  • Assessment: Prepare materials for fact-sheet products as requested by students (paper, colored pencils, markers, computers).


Launch: Witnessing a Volcanic Eruption

Show images and/or videos of massive volcanic eruptions. Initially, keep the sound muted to allow students to form their own ideas. Ask students to describe or draw at least five observations and record any questions they have as they watch the video (or view images) in their science notebook.

After watching, direct students to discuss with a partner the following questions:

  • What was the event that was occurring?
  • What do you think occurs during a volcanic eruption? What would it feel and sound like if you were close by?
  • Are all eruptions the same? How are they similar and different?
  • Share your observations and questions with your partner. What materials are forced out of a volcano? Where do they go? (Note: Students should notice that lava comes out and becomes part of the land and ash comes out and becomes part of the atmosphere.)

Replay one of the videos. Draw student attention to the vast amounts of ash and gas that are forced into the atmosphere during explosive eruptions. Ask students to consider where that material goes and what effects it might have upon the planet.

  • Ask students to create a list of the various changes they would predict for the landscape and atmosphere over time after an eruption. Have them contribute to a class list on the board.

Investigate: Particles Matter

Part 1: A Volcanic Eruption

In this investigation, students will explore the effects of a volcanic eruption on the atmosphere by engaging in a simple model. At the end of this investigation, be sure to take time to evaluate the limitations of this model. Also, ask students which variable they changed and how this model represents a volcanic eruption. It is a good idea to ask students how they could modify the model to closely align with evidence, make predictions, and test ideas.

Assign students to groups of 3. After passing out the materials or asking students to collect them, students will prepare the materials and conduct the investigation as follows:

  1. In your science notebook, make the following data table. You will be using this data table to record your observations:

    Observations of a model showing effects of volcanic eruptions
    Baggie What does this represent? Describe Sketch Amount of Light
  2. Put on your safety glasses or goggles.
  3. At the very top of the baggie (by the seal), label each baggie. (Hint: Be sure not to mark on the main part of the baggie as this will obstruct the view of what’s going on inside.)
    1. Baggie 1 - This will be the control or normal atmosphere.
    2. Baggie 2 - This will model a volcano that spews gas.
    3. Baggie 3 - This will model an explosive volcano that spews gas, ash, and rock particles.

      Plastic baggie filled with air and standing on its end.

  4. In baggies 2 and 3, add about 1 teaspoon of baking soda.
  5. In baggie 3, add about 2 teaspoons of flour.
  6. In baggie 1, seal all but a small opening. Blow air into the baggie and seal. Set the baggie up on its end (alternatively, you can tape it to a wall). Record observations in your data table.
  7. In baggie 2, seal all but a small opening. Add 2 Tablespoons of vinegar and QUICKLY seal. Very GENTLY swirl the contents and set the baggie up on its end (or tape). Record observations in your data table.
  8. In baggie 3, seal all but a small opening. Add 2 Tablespoons of vinegar and QUICKLY seal. Very GENTLY swirl the contents and set the baggie up on its end (or tape). Record observations in your data table. Be sure to note what you think the model represents for each baggie; be descriptive

Part 2: The Sunlight

Explain to students that they will model light reaching Earth following a volcanic eruption. The flashlight represents the Sun, the white paper represents the surface of the earth, and the three baggies represent a control, a “normal” atmosphere, and after a volcanic eruption. (Hint: If a light meter is available, students might use this to detect the amount of light shining through the baggie.)

  1. Label 3 pieces of white copy paper with the labels below.

  • 1 (Control, normal atmosphere)
  • 2 (Volcano spewing gas)
  • 3 (Volcanic explosion)
  1. Tape the first paper (1) onto a wall. Without disturbing the contents, hold the first baggie (1) about 30 cm away from the paper, using the ruler as a guide to the distance. Have one team member use the flashlight to project a beam of light through the baggie so the light hits surface (the white paper). Have another team member use a pencil to shade in, on the white paper, what the surface looks like. The third team member will write down observations.

  2. Repeat step 1. with baggies (2) and (3).

Ask students to answer the following questions in their notebook.

  • In which of the three examples did the “sunlight” shine through and reach the “Earth’s surface” the most? In which did it reach the least? Explain why.

  • How does this model represent what happens to the atmosphere during a volcanic eruption? Use pictures, words, and your experience using the model to help you explain your answer.

  • Imagine that you conducted this investigation on a much larger scale. Use what you’ve learned so far, and what you know about weather patterns, to predict what the atmospheric effects would be very close to the volcanic eruption, hundreds of miles away, and thousands of miles away.

  • How do you think that the amount of ash (and other, smaller, particles forced into the atmosphere) affect temperature at the Earth’s surface? How would the temperature be affected over time? (Hint: Think about the Sun and its importance to us on Earth.)

  • Handout Volcanic Eruption, Climate Disruption and have students draw graphs of their hypothesis.

Develop: Global Effects

Distribute the reading: How Volcanoes Influence Climate

  1. In groups of 3, ask students to read the short articleHow Volcanoes Influence Climate. Assign a role to each student in the group, directing them to switch roles for each paragraph
    1. Reader:This student will read the paragraph out loud.
    2. Annotator: This student will circle words or phrases that are unfamiliar, underline key ideas, put checkmarks next to ideas that are clearly understood, and write question marks next to any text they have a question about.
    3. Summarizer: This student summarizes the paragraph
  2. Hand out the Student Page Volcanic Eruption, Climate Disruption to each student. Explain the illustrations at the top that show what the Sun looked like before, during, and at several times after an eruption. Explain the axes of the graphs and the student directions.
    1. Ask students to draw a graph of the relative amount of ash in the atmosphere based on the illustrations of the Sun. (Answer: Large amount of ash right after the eruption and then amount of ash decreases gradually over time.)
    2. Summarize results as a class. (Answer: Temperature curve should be the inverse of the ash curve - i.e., when the ash amount is greatest, temperature is lowest, when the ash amount is lower, the temperature is higher.)
  3. Hand out the squares from the Volcanic Eruption: Sequence of Events. Ask students to work in their groups to arrange the squares in order that the events take place. Then, check with another group. Review the answers as a class. Ask students to record the events, in order, in their notebooks.
  • Create a set of images that show the sequence of events, in the Earth’s atmosphere during and after a volcanic eruption.

  • Describe the impact of volcanic eruptions both regionally and globally.

  • Create a hypothesis about how volcanic eruptions impact other parts of the Earth system (biosphere, hydrosphere, cryosphere, geosphere).

  • Investigate what causes volcanoes and where volcanoes are located in their country or state.

  • Explore how different materials that spew into the atmosphere stay aloft for different amounts of time, by creating a model with sediment of various sizes settling in a jar of water. Observe how larger, heavier particles settle to the bottom of a jar before smaller, lighter particles.


Ask students to create a one-page fact sheet informing the community about how volcanoes impact climate. Encourage creativity, including using comics, cartoons, color, poetry, slogans, and so on to capture the audience’s attention and educate their community. Share the assessment rubric with students prior to beginning the project. Use the same rubric to assess student understanding.

Download the assessment rubric for grading the fact sheet.


A gas plume arising from Augustine Volcano

A gas plume arising from Augustine Volcano during eruption in 2005-2006.


Scientists who specialize in the study of climate (climatologists) have identified three major contributors to climate change: the solar cycle, extreme or persistent volcanic eruptions, and the release of heat-trapping gases into the atmosphere, largely as byproducts of burning fossil fuels.

Volcanoes can have a significant long- and short-term effect on the global climate and environment. All volcanoes are different; some spew ash and gases while others have eruptions that are mostly lava. Very explosive volcanic eruptions can send tiny particulates (aerosols) and ash high in the atmosphere. Ash is heavier than aerosols and tends to fall out of the atmosphere within a few days or weeks. When an eruption sends aerosols, gas, and ash high enough, they can get into the stratosphere. In the stratosphere, they can spread out worldwide. Over time, they influence the composition of the atmosphere.

Anything in the sky that shades the Earth, causing less solar radiation to get to the planet's surface, will cause a change in the planet's temperature. If particles get into the stratosphere, travel worldwide, and stay up there for a couple of years, this can cause a slight cooling of global climate. Figure 1 shows how much global average temperature can cool after an eruption. The black line is global average surface temperature, and the orange vertical lines are times of eruptions.

Graph of change in global temperature over time since 1860 showing brief drops in temperature when major volcanic eruptions occured

 Volcanic eruptions related to global average surface temperature change over time

Gary Strand/NCAR

Therefore, short-term effects of volcanic eruptions include local devastation and a measurable decrease in the global temperature. Ash and gas produced by volcanic eruptions may spread throughout the globe in a matter of weeks. Gases rich in sulfur combine with water vapor to form sulfuric aerosols that remain in the atmosphere for up to several years following an eruption. These small droplets form a cloud layer that blocks light from the Sun, reducing the amount of energy reaching Earth. In addition, the aerosols absorb energy radiated from the earth’s surface. This process, known as “radiative forcing,” persists for several years and results in surface temperatures that are cooler in the summer and warmer in the winter.

Related Resources



This resource was adapted from NCAR's Climate Discovery revised in 2018 by educator Cynthia Long.