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What experiments could I do at home that would prove (to even the most skeptical) that our actions are causing a change in climate?

This is a common and understandable question. Many of us want to see and test things for ourselves. However, when it comes to a phenomenon as vast and complex as anthropogenic global warming (AGW), proving it with home-based experiments is, frankly, not feasible. Let’s explore why.

If I measure the amount of heat absorbed by CO2 in my bedroom with an IR spectrometer, does that prove that CO2 is responsible for global warming? It might demonstrate that CO2 absorbs infrared radiation, a key property of a greenhouse gas. ¹ But this doesn’t tell us much about CO2 concentrations elsewhere, the scale of its effect globally, or definitively link it to human activity as the primary driver of recent climate change. Also, where does CO2 even come from?

If I collect the exhaust gases from burning gasoline and determine the amount of CO2 released with a bicarbonate indicator, this could tell me the amount of CO2 produced by running my car on gasoline. ² And I could guess that my car is similar to most others, and extrapolate to calculate the output of all cars worldwide. But does this imply that humans are causing climate change? No. Why would this specific amount of extra CO2 necessarily heat the entire atmosphere? And anyway, don’t plants absorb CO2?

If I collect data on the temperature, rainfall, humidity, and atmospheric CO2 concentration of my backyard for the next 50 years and see a positive correlation between temperature and CO2 concentration, does this prove anthropogenic climate change? And can we generalize these results worldwide? No. Correlation does not imply causation. Local variations are immense, and geography is a significant confounder. A backyard is not a global climate system.

While directly proving AGW in its entirety is beyond the scope of home experimentation, some simple activities can help illustrate key concepts related to climate change:

1. Ocean Acidification Demonstration:
   • Materials: Two clear glass containers, tap water, pH indicator (like red cabbage juice or a pH meter), a straw, and some small seashells or pieces of chalk.
   • Procedure: Fill both containers with water and note the initial pH. In one container, gently blow air through the straw into the water for several minutes (the CO2 in your breath will dissolve and form carbonic acid). Measure the pH again; it should be lower (more acidic). Place seashells in both containers and observe them over a few days to a week. You may notice the shells in the more acidic water start to degrade more noticeably.
   • Relevance: This demonstrates how increased CO2 dissolving in water makes it more acidic, illustrating the principle behind ocean acidification, a significant consequence of rising atmospheric CO2. ³
2. Albedo Effect (Ice Melting) Demonstration:
   • Materials: Two ice cubes of similar size, two shallow dishes, a piece of black paper, and a piece of white paper (or aluminum foil).
   • Procedure: Place the black paper in one dish and the white paper in the other. Put an ice cube on each piece of paper. Position both dishes in direct sunlight or under a strong lamp. Observe which ice cube melts faster.
   • Relevance: The ice on the black paper should melt faster because darker surfaces absorb more heat (lower albedo), while lighter surfaces reflect more heat (higher albedo). This illustrates how melting ice and snow expose darker land and ocean surfaces, which then absorb more solar radiation, leading to further warming—a positive feedback loop in climate change. ⁴

The point is, it is not possible for a skeptical individual to comprehensively prove anthropogenic climate change with isolated experiments. However, the inverse has a different weight. If an individual could, through a scientifically rigorous and reproducible experiment, demonstrate that a fundamental physical law underpinning climate science (e.g., CO2 does not absorb infrared radiation as expected, or burning fossil fuels does not produce CO2) is incorrect, then yes, our understanding would need reevaluation. But such a finding would need to overturn decades of established physics and chemistry, which is highly improbable.

For instance:

• If CO2 didn’t absorb large amounts of infrared radiation (a principle verifiable in sophisticated labs), then it could not act as a significant greenhouse gas, and its role in heating the planet would be minimal.
• If burning gasoline (and other fossil fuels) didn’t release substantial CO2, then the attribution of human activity as the primary cause of increased atmospheric CO2 would be tenuous.

Causation does imply correlation. So if there were no correlation observed globally between rising CO2 levels and rising temperatures (when accounting for other factors), then we could indeed question anthropogenic climate change.

So then, what evidence do we have for anthropogenic climate change that cannot be easily gathered by an individual in their backyard? The understanding of AGW is built upon a vast array of data and analysis from multiple independent lines of scientific inquiry conducted worldwide over many decades.

1. Historical Climate Data: Evidence from ice cores⁵, tree rings, and geological samples tells us about Earth’s climate tens of thousands to millions of years ago, long before significant human industrial activity. This data establishes a baseline of natural climate variability, which we can compare to the present.
2. Modern Global Monitoring:
   • Comprehensive measurements of global average temperatures⁶ show a clear and accelerating warming trend, especially since the late 19th century.
   • Data on ocean heat content and acidification⁷ reveal that oceans are absorbing vast amounts of heat and CO2, leading to chemical changes.
   • Precise measurements of atmospheric CO2 concentrations⁸ show levels unprecedented in human history, with isotopic analysis linking the increase to the burning of fossil fuels.
   • Monitoring of sea levels and ice sheet mass⁹ (glaciers, Greenland, Antarctica) by satellites and ground stations shows significant ice melt and sea-level rise.
3. Climate Models and Attribution: Sophisticated climate models, grounded in fundamental physics and chemistry, allow scientists to simulate Earth’s climate system. By running simulations with and without human-caused greenhouse gas emissions, scientists can distinguish the effects of natural factors (solar variations, volcanoes) from anthropogenic factors. These studies consistently show that human activities are the dominant driver of the observed warming since the mid-20th century. ¹⁰
4. Understanding Biogeochemical Cycles: Scientists have a detailed understanding of the carbon cycle, including the rates at which CO2 is absorbed by oceans, plants, and rocks. This knowledge allows us to track the fate of human-emitted CO2 and confirm that natural sinks are not keeping pace with emissions, leading to its accumulation in the atmosphere.

Conclusion:

While the desire to personally verify complex scientific claims is understandable, proving anthropogenic global warming through individual home experiments is not feasible due to the global scale, intricate feedback mechanisms, and long timescales involved. Home experiments can, however, be valuable for demonstrating some of the underlying principles. The robust scientific consensus on AGW rests on an extensive and consistent body of evidence gathered from around the world, analyzed with rigorous methods, and corroborated across multiple scientific disciplines. This collective scientific endeavor provides the comprehensive understanding that individual efforts cannot replicate.