It's a Gas!

Test your knowledge of carbon dioxide and its role in global warming.

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More Info / References

OCO-2 mission home page

Carbon dioxide data from NOAA

NASA's Global Climate Change website

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1. PULLING YOUR OWN

The average American adds how much carbon dioxide to the atmosphere per year?

The average American produces about15.52 tons of CO2 per year. In contrast, the average Chinese resident adds about 7.38 tons of CO2 per year, and the average Indian adds about 1.91 tons per year.
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2. TO AND FRO

The graph to the left, called the Keeling curve, maps the overall rise in atmospheric carbon dioxide since 1958. But why does it have a zig-zag shape, showing cyclical rises and falls in carbon dioxide levels?

The uptake of carbon dioxide by forests and plants varies with the seasons. Most vegetation is in the northern hemisphere, where most land is located. In the northern spring, new plant growth uses more carbon dioxide. In the northern fall, plants and leaves die and release the gas back into the atmosphere.
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3. NOW AND THEN

In the 10,000 years before the Industrial Revolution in 1751, carbon dioxide levels rose less than 6 percent. Since then, they've risen by:

From 1751-2021, humans added 1718 billion tons of carbon dioxide to the atmosphere, nearly a 49% increase. About eighty percent of all human-produced carbon dioxide comes from burning coal, natural gas, oil and gasoline.
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4. CRUEL FUEL

Burning fossil fuels is the major source of human-produced carbon dioxide. But what is the second leading source?

Forest clearing produces about eleven percent of current carbon dioxide emissions. Tropical deforestation accounts for most of this today.
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5. HOT HOUSE

What is the main control knob governing Earth's temperature?

A large amount of physical evidence shows that carbon dioxide (CO2) is the single most important greenhouse gas in the atmosphere controlling Earth's temperature. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does.
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6. FROM ME TO YOU

We produce more than 36 billion tons of carbon dioxide per year. Where does the majority of it end up?

Forty to 50 percent of the carbon dioxide stays in the air, and about 30 percent is dissolved in the oceans. Scientists are not sure about the rest. They believe it is absorbed by forests, soil and crops.
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7. REDUCTION FUNCTION

Which of the following would have the biggest impact on reducing carbon emissions?

Shutting down fossil fuel plants and moving to clean, renewable energy sources (e.g., the sun and wind) would have the biggest impact.
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8. OUR NEIGHBORS

Which planets have carbon dioxide in their atmosphere?

Both Venus and Mars have atmospheres made of about 96 percent carbon dioxide. Earth's atmosphere started out like Venus' atmosphere. But Earth's ocean absorbed much of this carbon dioxide, and as photosynthesis evolved, plants converted carbon dioxide to oxygen, increasing oxygen levels in the air from 0.01 percent to 21 percent today.
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9. THE LONG VIEW

If humans stopped emitting carbon dioxide tomorrow, what would happen to global temperatures?

Even if we stopped all carbon emissions right now, the hundreds of billions of tons of carbon dioxide that have been pumped into the atmosphere and absorbed by the oceans since the Industrial Revolution would continue to warm the planet. For how long? Scientists are not sure, but evidence shows that elevated global temperatures would persist for many centuries after ceasing the burning of fossil fuels.
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