Atmospheric CO₂ converter
Convert a CO₂ concentration in ppm to the mass of carbon or CO₂ it means in the whole atmosphere, and back.
That's about the same as the 2024 average. That is 51.43 % above the pre-industrial 280 ppm.
What it means
How much CO₂ is that?
Whole-atmosphere totals: 1 ppm = 2.124 GtC = 7.78 GtCO₂. About half of each year’s emissions stays in the air; oceans and land take the rest.
Every unit
That CO₂ in every unit
Learn
Three things worth knowing
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×2.12 for carbon
ppm × 2.124 = GtC; × 7.78 = GtCO₂. 40 GtCO₂ is about 5 ppm before the oceans take half.
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The Keeling Curve
Charles David Keeling began measuring CO₂ on Mauna Loa in 1958, at 315 ppm; the record has risen every year since.
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Carbon or CO₂
A tonne of carbon is 3.67 tonnes of CO₂. Budgets in GtC and GtCO₂ differ by that factor.
Shortcuts
Popular CO₂ level conversions
Background
About atmospheric CO₂
CO₂ is measured as a mixing ratio in parts per million: about 280 ppm before industry, 424 ppm in 2024. Each ppm of the whole atmosphere is 2.124 billion tonnes of carbon, 7.78 Gt of CO₂.
Humans emit about 40 Gt of CO₂ a year; roughly half stays in the air, adding about 2.5 ppm.