Volcanic Eruptions and Global Cooling: The 1816 Year Without a Summer

Standards Alignment:

• Performance Expectation: HS-ESS2-4
• Evidence Statements: Students use a model to describe how variations in the flow of energy into and out of Earth’s systems result in changes in climate, including how volcanic stratospheric aerosols alter planetary albedo, reduce surface radiation, and produce multi-year negative temperature anomalies.
• Science and Engineering Practices: Analyzing and Interpreting Data; Constructing Explanations for Earth and Space Science
• Disciplinary Core Ideas: ESS2.D: Weather and Climate
• Crosscutting Concepts: Cause and Effect; Energy and Matter

Simulation Link: Tambora 1816: Year Without a Summer

Estimated Time: 50–60 minutes

Materials: Computer or tablet with internet access; this handout

Engage: The Year Without a Summer

In April 1815, Mount Tambora in present-day Indonesia erupted — the most powerful volcanic eruption in recorded human history. Over the following year, something strange happened worldwide. In New England, snow fell in June. In Europe, crops failed through the summer. In China, widespread flooding destroyed the harvest. Historians now call 1816 “The Year Without a Summer.”

Tens of thousands of people died from famine-related causes. The disruption triggered one of the largest mass migrations in 19th-century North America. The unrelenting darkness and cold reportedly inspired Mary Shelley to write Frankenstein.

Discussion Prompt: How could a single volcanic eruption on one island change the climate of the entire planet for more than a year?

Write your initial hypothesis below before you begin the investigation:

My initial hypothesis: ___________________

Explore: Using the Simulation

Open the Tambora 1816 simulation. Familiarize yourself with the controls:

Monitored outputs:

Before each trial: click Reset, set your variables, then click Run Eruption. Let the simulation complete one full cycle before recording data.

Part 1 — Effect of Eruption Magnitude (VEI)

Set Eruption Latitude to Mid-Latitude (45° N/S) for all trials in Part 1. Vary only the VEI.

Analysis Questions — Part 1:

1. As VEI increases, what happens to aerosol optical depth? Describe the relationship.

2. What happens to the percentage of surface radiation as aerosol depth increases? Is this relationship direct or inverse? Explain using your data.

3. How does peak temperature anomaly change as VEI increases? Use at least two specific data points from your table to support your answer.

Part 2 — Effect of Eruption Latitude

Set VEI to 7 (approximating the 1815 Tambora eruption) for all trials in Part 2. Vary only the latitude.

Analysis Questions — Part 2:

1. Which eruption latitude produced the largest global temperature anomaly? Propose a reason based on how aerosols spread in the atmosphere.

2. Compare the recovery times across the three latitudes. What does this suggest about how eruption location affects the duration of climate disruption?

Explain: Tracing the Causal Chain

Using your data from Parts 1 and 2, answer the following questions to build a step-by-step causal explanation.

1. Aerosols and Albedo: How do volcanic stratospheric aerosols change Earth’s albedo? What does a higher albedo mean for the amount of solar energy reaching the surface?

2. Albedo and Radiation: Using the Cause and Effect crosscutting concept, explain how an increase in aerosol optical depth leads to a decrease in surface radiation. Cite a specific data value to support your reasoning.

3. Radiation and Temperature: How does reduced surface radiation cause a negative temperature anomaly? Connect this to the Energy and Matter crosscutting concept (specifically, the energy available to heat Earth’s surface).

Elaborate: Connecting to HS-ESS2-4

1. The 1815 Tambora Eruption had a VEI of approximately 7 and occurred at an equatorial latitude. Using your Trial 5 or Trial 6 data as a reference (VEI 7), estimate:
   • The approximate peak temperature anomaly caused by Tambora: ___ °C
   • The approximate recovery time: ___ years

   How well does this match the historical record of 1–2 years of cooling following 1816?

2. Scaling up: In 1991, Mount Pinatubo (Philippines, equatorial, VEI 6) caused a global average temperature drop of about 0.5°C for 1–2 years. Does your simulation data for VEI 6 at equatorial latitude show a similar magnitude? Explain any differences between the simulation and the real-world event.

Evaluate: Final Explanation

Using all of the evidence you collected in this task, construct a scientific explanation for how the 1815 eruption of Mount Tambora caused the “Year Without a Summer” in 1816.

Your explanation must include all of the following:

• A claim identifying the causal mechanism (what physical process connects the eruption to global cooling)
• Evidence from your data table — cite at least two specific numerical values (e.g., aerosol depth, radiation %, or temperature anomaly)
• Reasoning connecting your evidence to the causal chain: eruption → aerosol loading → increased albedo → reduced surface radiation → negative temperature anomaly
• An explanation of why the cooling was temporary (what caused Earth’s climate to recover over 1–3 years)
• A brief statement of one limitation of the simulation model (something it does not capture about the real 1816 event)

Teacher Notes

Standards Alignment

Evidence Statements Addressed

• Using a model: Students use the Tambora simulation to investigate how varying eruption parameters (VEI, latitude) affects aerosol loading, albedo, radiation, and temperature — directly modeling how variations in energy flow produce climate changes.
• Identifying patterns: Students identify quantitative trends in the data tables (increasing VEI → greater anomaly; equatorial eruptions → broader impact) and use them to construct explanations.
• Constructing explanations: The final Evaluate section requires students to write a complete claim-evidence-reasoning explanation integrating all three dimensions.

Suggested Instructional Sequence

This task works best as a summative formative assessment following instruction on:

• Earth’s energy balance (incoming solar radiation, albedo, outgoing infrared)
• The greenhouse effect and factors affecting surface temperature
• Basic reading and interpretation of time-series graphs

Extension Options

• Compare the Tambora event to the 1991 Pinatubo eruption (VEI 6) using published temperature records
• Research the “Volcanic Winter” hypothesis and its potential implications for food security
• Investigate how the 1816 event inspired early climate science (e.g., Benjamin Franklin’s early hypothesis about volcanic cooling)
• Discuss policy implications: should nations maintain stratospheric aerosol injection as a geoengineering option to counteract anthropogenic warming?