CO2 in the air
Carbon dioxide in the air is measured in parts per million (ppm): how many of every million molecules of dry air are CO2. It has been measured at Mauna Loa in Hawaii since 1958, first by Charles David Keeling.
The latest reading
426.07 ppm
The average for September 2026, measured at Mauna Loa in Hawaii.
- Compared with a year before
- September 2026 was 1.70 ppm higher than September 2025.
- The highest month so far
- 432.34 ppm, in May 2026.
Source: NOAA, as of 16 October 2026.
The Keeling curve
Each point is the average for one month. Every year the line goes down and up: forests in the north take in carbon dioxide as they grow in summer, and give it back as their leaves rot in winter. Year after year, the line also climbs higher, because people burn coal, oil and gas.
Monthly mean CO2 at Mauna Loa rose from 315.71 ppm in March 1958 to 426.07 ppm in September 2026, rising and falling with the seasons each year. The annual mean first passed 400 ppm in 2015. The highest monthly mean so far is 432.34 ppm, in May 2026.
Show the data as a table
| Year | Annual mean (ppm) |
|---|---|
| 1959 | 315.98 |
| 1960 | 316.91 |
| 1961 | 317.64 |
| 1962 | 318.45 |
| 1963 | 318.99 |
| 1964 | 319.62 |
| 1965 | 320.04 |
| 1966 | 321.37 |
| 1967 | 322.18 |
| 1968 | 323.05 |
| 1969 | 324.62 |
| 1970 | 325.68 |
| 1971 | 326.32 |
| 1972 | 327.46 |
| 1973 | 329.68 |
| 1974 | 330.19 |
| 1975 | 331.13 |
| 1976 | 332.03 |
| 1977 | 333.84 |
| 1978 | 335.41 |
| 1979 | 336.84 |
| 1980 | 338.76 |
| 1981 | 340.12 |
| 1982 | 341.48 |
| 1983 | 343.15 |
| 1984 | 344.87 |
| 1985 | 346.35 |
| 1986 | 347.61 |
| 1987 | 349.31 |
| 1988 | 351.69 |
| 1989 | 353.20 |
| 1990 | 354.45 |
| 1991 | 355.70 |
| 1992 | 356.54 |
| 1993 | 357.21 |
| 1994 | 358.96 |
| 1995 | 360.97 |
| 1996 | 362.74 |
| 1997 | 363.88 |
| 1998 | 366.84 |
| 1999 | 368.54 |
| 2000 | 369.71 |
| 2001 | 371.32 |
| 2002 | 373.45 |
| 2003 | 375.98 |
| 2004 | 377.70 |
| 2005 | 379.98 |
| 2006 | 382.09 |
| 2007 | 384.02 |
| 2008 | 385.83 |
| 2009 | 387.64 |
| 2010 | 390.10 |
| 2011 | 391.85 |
| 2012 | 394.06 |
| 2013 | 396.74 |
| 2014 | 398.81 |
| 2015 | 401.01 |
| 2016 | 404.41 |
| 2017 | 406.76 |
| 2018 | 408.72 |
| 2019 | 411.65 |
| 2020 | 414.21 |
| 2021 | 416.41 |
| 2022 | 418.53 |
| 2023 | 421.08 |
| 2024 | 424.61 |
| 2025 | 427.35 |
800,000 years
Bubbles of old air trapped in Antarctic ice record CO2 for the last 800,000 years. The ice-core record ends in 1958 and Mauna Loa carries on from 1959. The dashed line marks the join.
For 800,000 years before the industrial era, ice cores show CO2 between 174 and 299 ppm, rising and falling with the ice ages. Measured directly at Mauna Loa, the annual mean was 316 ppm in 1959 and 427 ppm in 2025.
Show the data as a table
| Years before 1950 | Mean (ppm) | Lowest | Highest | Samples |
|---|---|---|---|---|
| 800,000 to 810,000 | 203.1 | 198.7 | 207.5 | 8 |
| 790,000 to 800,000 | 212.7 | 197.9 | 230.6 | 11 |
| 780,000 to 790,000 | 256.2 | 235.5 | 269.4 | 17 |
| 770,000 to 780,000 | 242.7 | 229.6 | 254.9 | 19 |
| 760,000 to 770,000 | 224.0 | 214.0 | 233.7 | 17 |
| 750,000 to 760,000 | 206.6 | 191.3 | 226.9 | 15 |
| 740,000 to 750,000 | 187.7 | 183.4 | 190.2 | 15 |
| 730,000 to 740,000 | 209.0 | 185.6 | 217.9 | 17 |
| 720,000 to 730,000 | 213.0 | 210.0 | 219.2 | 16 |
| 710,000 to 720,000 | 216.3 | 189.9 | 227.6 | 16 |
| 700,000 to 710,000 | 234.2 | 230.5 | 238.8 | 26 |
| 690,000 to 700,000 | 239.3 | 235.8 | 243.7 | 27 |
| 680,000 to 690,000 | 225.6 | 219.1 | 233.6 | 22 |
| 670,000 to 680,000 | 210.5 | 191.5 | 232.7 | 16 |
| 660,000 to 670,000 | 185.9 | 173.7 | 194.0 | 16 |
| 650,000 to 660,000 | 191.1 | 184.1 | 200.3 | 14 |
| 640,000 to 650,000 | 192.8 | 189.9 | 196.2 | 9 |
| 630,000 to 640,000 | 194.9 | 188.8 | 200.5 | 8 |
| 620,000 to 630,000 | 225.1 | 199.5 | 245.9 | 12 |
| 610,000 to 620,000 | 254.9 | 248.3 | 259.7 | 10 |
| 600,000 to 610,000 | 245.2 | 232.4 | 259.2 | 7 |
| 590,000 to 600,000 | 230.3 | 216.3 | 248.1 | 15 |
| 580,000 to 590,000 | 228.8 | 206.7 | 250.2 | 16 |
| 570,000 to 580,000 | 250.7 | 246.3 | 252.9 | 23 |
| 560,000 to 570,000 | 246.0 | 228.3 | 254.5 | 25 |
| 550,000 to 560,000 | 230.2 | 208.8 | 250.5 | 24 |
| 540,000 to 550,000 | 207.8 | 202.5 | 212.9 | 10 |
| 530,000 to 540,000 | 205.9 | 190.5 | 221.2 | 14 |
| 520,000 to 530,000 | 235.5 | 222.7 | 247.7 | 11 |
| 510,000 to 520,000 | 241.1 | 233.4 | 247.2 | 12 |
| 500,000 to 510,000 | 233.9 | 228.2 | 240.3 | 13 |
| 490,000 to 500,000 | 240.5 | 230.6 | 252.8 | 15 |
| 480,000 to 490,000 | 230.4 | 218.8 | 242.0 | 14 |
| 470,000 to 480,000 | 230.7 | 205.5 | 245.6 | 16 |
| 460,000 to 470,000 | 201.4 | 190.7 | 210.0 | 10 |
| 450,000 to 460,000 | 200.8 | 192.5 | 208.3 | 11 |
| 440,000 to 450,000 | 202.4 | 199.1 | 208.1 | 7 |
| 430,000 to 440,000 | 211.9 | 200.3 | 227.2 | 7 |
| 420,000 to 430,000 | 263.6 | 242.5 | 273.8 | 14 |
| 410,000 to 420,000 | 274.5 | 264.9 | 283.5 | 11 |
| 400,000 to 410,000 | 280.4 | 274.7 | 285.6 | 9 |
| 390,000 to 400,000 | 267.6 | 258.1 | 277.1 | 6 |
| 380,000 to 390,000 | 239.7 | 227.0 | 246.8 | 5 |
| 370,000 to 380,000 | 214.1 | 199.9 | 229.6 | 5 |
| 360,000 to 370,000 | 194.8 | 185.8 | 206.3 | 4 |
| 350,000 to 360,000 | 209.8 | 193.0 | 221.1 | 5 |
| 340,000 to 350,000 | 218.2 | 200.7 | 250.1 | 7 |
| 330,000 to 340,000 | 272.9 | 239.6 | 298.6 | 16 |
| 320,000 to 330,000 | 262.0 | 249.2 | 271.9 | 11 |
| 310,000 to 320,000 | 245.6 | 226.2 | 272.6 | 13 |
| 300,000 to 310,000 | 238.2 | 225.8 | 250.2 | 11 |
| 290,000 to 300,000 | 216.0 | 206.0 | 234.9 | 10 |
| 280,000 to 290,000 | 225.4 | 211.0 | 231.4 | 9 |
| 270,000 to 280,000 | 195.6 | 184.7 | 204.5 | 9 |
| 260,000 to 270,000 | 204.9 | 187.2 | 228.1 | 10 |
| 250,000 to 260,000 | 201.2 | 195.4 | 213.9 | 9 |
| 240,000 to 250,000 | 250.2 | 214.7 | 280.2 | 12 |
| 230,000 to 240,000 | 242.9 | 232.4 | 252.1 | 12 |
| 220,000 to 230,000 | 218.0 | 203.3 | 235.5 | 11 |
| 210,000 to 220,000 | 246.4 | 239.5 | 257.4 | 16 |
| 200,000 to 210,000 | 237.2 | 226.3 | 250.9 | 16 |
| 190,000 to 200,000 | 228.3 | 218.0 | 242.6 | 8 |
| 180,000 to 190,000 | 210.6 | 198.1 | 231.3 | 7 |
| 170,000 to 180,000 | 195.6 | 189.4 | 207.7 | 7 |
| 160,000 to 170,000 | 192.1 | 183.8 | 204.3 | 8 |
| 150,000 to 160,000 | 194.8 | 185.5 | 202.5 | 7 |
| 140,000 to 150,000 | 196.4 | 193.6 | 201.8 | 6 |
| 130,000 to 140,000 | 221.5 | 192.8 | 251.8 | 12 |
| 120,000 to 130,000 | 275.7 | 260.6 | 285.8 | 23 |
| 110,000 to 120,000 | 267.9 | 246.7 | 277.7 | 16 |
| 100,000 to 110,000 | 243.7 | 236.4 | 257.6 | 17 |
| 90,000 to 100,000 | 238.5 | 229.7 | 246.2 | 15 |
| 80,000 to 90,000 | 233.2 | 217.8 | 250.8 | 20 |
| 70,000 to 80,000 | 233.0 | 215.6 | 249.9 | 24 |
| 60,000 to 70,000 | 205.2 | 197.2 | 217.3 | 28 |
| 50,000 to 60,000 | 216.8 | 204.4 | 231.3 | 30 |
| 40,000 to 50,000 | 205.9 | 192.6 | 222.7 | 51 |
| 30,000 to 40,000 | 200.3 | 182.9 | 214.4 | 119 |
| 20,000 to 30,000 | 189.2 | 180.6 | 197.7 | 88 |
| 10,000 to 20,000 | 229.3 | 184.9 | 270.1 | 290 |
| 0 to 10,000 (to 1958) | 284.6 | 257.6 | 316.3 | 285 |
| 1959 (Mauna Loa) | 316.0 | 316.0 | 316.0 | 1 |
| 2025 (Mauna Loa) | 427.4 | 427.4 | 427.4 | 1 |
Country by country
Every country's CO2 from fossil fuels and industry: total, per person and per unit of GDP, how it ranks, and how it has changed since 1950. See all countries.
The year you were born
See how much CO2 was in the air the year you were born, and how much there is now, as a card you can share. Or pick from every year.
Sources
- Monthly mean CO2, Mauna Loa Observatory, Hawaii. Dr. Xin Lan, NOAA/GML (gml.noaa.gov/ccgg/trends/) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu/). Retrieved 16 October 2026. Terms.
- Annual mean CO2, Mauna Loa Observatory, Hawaii. Dr. Xin Lan, NOAA/GML (gml.noaa.gov/ccgg/trends/) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu/). Retrieved 16 October 2026. Terms.
- Antarctic Ice Cores Revised 800KYr CO2 Data (Bereiter et al. 2015 composite): age and CO2. Bereiter, B.; Eggleston, S.; Schmitt, J.; Nehrbass-Ahles, C.; Stocker, T.F.; Fischer, H.; Kipfstuhl, S.; Chappellaz, J.A. (2015-02-04): NOAA/WDS Paleoclimatology - Antarctic Ice Cores Revised 800KYr CO2 Data. NOAA National Centers for Environmental Information. https://doi.org/10.25921/n8y4-bp27. Accessed 2026-10-15. Publication: Bereiter, B. et al. (2015), Revision of the EPICA Dome C CO2 record from 800 to 600 kyr before present, Geophysical Research Letters, https://doi.org/10.1002/2014GL061957. Retrieved 15 October 2026. Terms. Trimmed from the published file.
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