Global atmospheric CO₂: annual means and growth

NOAA global marine-surface annual CO₂ means, within-year increases and reported uncertainties, with a chart of 1980–2025.

  • Global marine-surface measurements; chart 1980–2025; growth series 1959–2025 and annual means 1979–2025.
  • Snapshot: 14 October 2026 · Free CSV + ZIP
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What the chart shows

NOAA’s estimated within-year CO₂ increase slowed from 3.76 ppm in 2024 to 2.06 ppm in 2025. The 2025 annual mean still reached 425.62 ppm.

The within-year increase was 45.2% smaller in 2025, but it remained positive. The annual mean was the highest in this available 1979–2025 global marine-surface mean series. This is a statement about the instrumental dataset, not a geological record.

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Two NOAA global CO₂ panels: the annual mean rises to 425.62 ppm in 2025, while the estimated within-year increase falls from 3.76 ppm in 2024 to 2.06 ppm in 2025, with reported uncertainty.
Desktop original; mobile chart. Within-year increase is an estimated start-to-end-of-year concentration change in ppm; it is not a percentage, emission mass, or the difference between consecutive annual means. The 2025 difference between annual means is 2.83 ppm and is not substituted for the 2.06 ppm growth estimate.

Method

Retain NOAA’s distinct annual-mean and within-year-growth metrics. Ignore raw CSV comment lines, rename fields and outer-join one row per year. Keep all 67 growth years with blank means before 1979; chart all 46 years 1980–2025. No interpolation, smoothing or outlier removal is used.

Definitions and limits

  • Within-year increase is an estimated start-to-end-of-year concentration change in ppm; it is not a percentage, emission mass, or the difference between consecutive annual means. The 2025 difference between annual means is 2.83 ppm and is not substituted for the 2.06 ppm growth estimate.
  • NOAA reports growth uncertainty as a 68% interval; plotted whiskers are the value plus or minus that reported uncertainty. Growth is 3.76 ± 0.11 ppm in 2024 and 2.06 ± 0.08 ppm in 2025.
  • The 2025 annual mean is 425.62 ± 0.05 ppm. Annual-mean uncertainty is network-derived and narrower than the desktop line width; the mobile chart shows growth whiskers and accompanies these full notes.
  • NOAA’s webpage and CSV describe different bootstrap ensemble sizes. Supplied uncertainties are preserved rather than recomputed, and no formal significance test is claimed.
  • Growth reflects net human and natural additions and removals, not fossil emissions alone. Earlier growth uses a Mauna Loa/South Pole approximation; 1980 starts the modern global-network growth series. Partial 2026 is excluded and source values may be revised.
  • Citation: Lan, X., Tans, P. and K.W. Thoning, Trends in globally-averaged CO₂ determined from NOAA Global Monitoring Laboratory measurements, version 2026-10, doi:10.15138/9N0H-ZH07. Retrieved 14 October 2026.

Sources and reuse

NOAA-produced government numerical data are in the US public domain; raw headers request source credit. Credit NOAA GML and Lan, Tans and Thoning with the cited dataset version. No NOAA endorsement is implied and no logos or third-party media are included. Original Meplar charts and code are separate works; no new license for them is asserted here.

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