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200811,386.36,28
200812,386.41,29
200901,386.63,30
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200904,386.93,29
200905,387.02,30
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201104,390.64,28
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201204,393.46,29
201205,393.54,30
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201211,395.01,29
201212,395.04,29
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201302,396.01,25
201303,395.85,30
201304,395.56,22
201305,396.41,28
201306,396.28,26
201307,396.93,21
201308,397.08,27
201309,396.98,27
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201311,397.14,30
201312,397.59,30
201401,397.55,31
201402,397.20,26
201403,398.20,22
201404,398.46,26
201405,398.38,22
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201410,399.47,25
201411,399.36,27
201412,399.64,29
201501,399.73,30
201502,399.58,27
201503,400.02,25
201504,400.27,26
201505,400.51,30
201506,400.48,29
201507,400.92,24
201508,400.85,28
201509,401.25,25
201510,401.68,28
201511,402.11,26
201512,402.51,30
201601,402.23,26
201602,403.24,25
201603,403.38,28
201604,404.59,23
201605,404.23,29
201606,404.41,26
201607,404.05,28
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201610,405.03,29
201611,405.53,27
201612,405.13,29
201701,405.86,27
201702,405.63,26
201703,405.76,23
201704,406.18,26
201705,406.17,27
201706,406.48,26
201707,406.81,28
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201709,406.97,26
201710,407.01,27
201711,407.15,26
201712,407.52,31
201801,407.69,29
201802,407.47,28
201803,407.91,29
201804,407.45,21
201805,407.74,24
201806,408.39,29
201807,408.35,27
201808,408.89,31
201809,409.10,29
201810,409.41,30
201811,410.04,24
201812,409.81,30
201901,410.56,26
201902,410.89,27
201903,410.49,28
201904,410.52,27
201905,411.14,28
201906,411.52,27
201907,411.39,25
201908,411.87,29
201909,412.13,29
201910,411.93,29
201911,412.27,26
201912,412.49,31
202001,413.12,29
202002,413.25,28
202003,413.03,26
202004,413.41,28
202005,413.57,27
202006,413.98,27
202007,414.03,31
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202009,414.88,29
202010,414.69,30
202011,414.91,27
202012,414.76,30
202101,415.01,29
When measurements of atmospheric carbon dioxide began at Mauna Loa Observatory in 1958, monthly averages (light purple line) were below 320 parts per million (ppm). By the start of 2025, the 12-month running average had reached 425 ppm.
The amount of carbon dioxide in the atmosphere during ice ages and warm periods over the past 800,000 years, based on Antarctic ice core data (Lüthi, D. et al, 2008). On this time scale, the increase to 2024’s 422.8 parts per million (bright magenta dot) looks practically instantaneous.
The modern record of atmospheric carbon dioxide levels began with observations recorded at Mauna Loa Observatory in Hawaii. This graph shows the station's monthly average carbon dioxide measurements since 1958 in parts per million (ppm). The seasonal cycle of highs and lows (small peaks and valleys) is driven by Northern Hemisphere summer vegetation growth, which reduces atmospheric carbon dioxide, and winter decay, which increases it. The long-term trend of rising carbon dioxide levels is driven by human activities. At Mauna Loa, the highest monthly value each year occurs in May. In May 2023, carbon dioxide hit 424 ppm—a new record. NOAA Climate.gov image, based on Mauna Loa monthly mean data from NOAA Global Monitoring Lab.
Atmospheric carbon dioxide (CO2) in parts per million (ppm) for the past 800,000 years based on ice-core data (light purple line) compared to 2024 concentrations (bright magenta dot). The peaks and valleys in the line show ice ages (low CO2) and warmer interglacials (higher CO2). Throughout that time, CO2 was never higher than 300 ppm (light purple dot, between 300,000 and 400,000 years ago). The increase over the last 60 years is 100 times faster than previous natural increases. In fact, on the geologic time scale, the increase from the end of the last ice age to the present value of 422.8 ppm (dashed magenta line) looks virtually instantaneous. Graph by NOAA Climate.gov based on data from Lüthi, et al., 2008, via NOAA NCEI Paleoclimatology Program.