Monthly CO2

Mauna Loa CO₂

September 2024

	NOAA-GML	SCRIPPS UCSD
Sep. 2024	422.03 ppm	421.60 ppm
Sep. 2023	418.51 ppm	418.06 ppm
Sep. 2022	415.91 ppm	415.42 ppm
Last Update:	Oct. 5, 2024	Oct. 4, 2024
View Data:	NOAA	Scripps

Mauna Loa Observatory (MLO) | Atmospheric CO₂
monthly mean concentrations | ppm = parts per million

Two independent records of CO₂ changes are maintained in parallel at Mauna Loa. A graph showing the two records together is available at the bottom of the Scripps CO₂ Program website. All-time monthly record highs for CO₂ are recorded at the CO₂ Records webpage.

Use the tabs below to view the latest monthly CO₂ data, charts and related links.

Mauna Loa CO₂

September 2024

	NOAA-GML	SCRIPPS UCSD
Sep. 2024	422.03 ppm	421.60 ppm
Sep. 2023	418.51 ppm	418.06 ppm
Sep. 2022	415.91 ppm	415.42 ppm
Last Update:	Oct. 5, 2024	Oct. 4, 2024
View Data:	NOAA	Scripps

Mauna Loa Observatory (MLO) | Atmospheric CO₂
monthly mean concentrations | ppm = parts per million

Use the tabs below to view the latest monthly CO₂ data, charts and related links.

Global

Global Monthly CO₂ Data

Global Monthly CO₂ Averages

July 2024

July 2024	421.20 ppm
July 2023	417.90 ppm
July 2022	415.67 ppm
Last Update:	Oct. 5, 2024
View Data:	NOAA global monthly data NOAA global trends web

Atmospheric CO₂monthly mean concentrations | ppm = parts per million
NOAA-ESRL-GMD CCGG global cooperative air sampling network

NOAA-ESRL’s Global Monitoring Division (GMD) operates the largest and most comprehensive global network of air sampling sites. In the 1970s, the GMD started air sampling programs at Mauna Loa and other sites around the world. GMD network coordination activities are based in Boulder, Colorado, USA.

NOAA publishes a monthly global average based on CO2 measurements by its distributed network of air sampling sites. Global averages have usually been posted a month after Mauna Loa averages are posted. For example, the Mauna Loa average for January has often been published in the first half of February, and the global average for January has often been published in the first half of March.

Despite seasonal variations at different latitudes, readings from observatories around the world show the same rising CO2 trend from one year to the next. In the book, CO2 Rising, Tyler Volk (2008) writes, "Data from Alaska and Samoa fit right in with the trend from Mauna Loa and the South Pole, where monitoring was begun nearly 20 years earlier. We are witnessing a global phenomenon. CO2 is rising everywhere, and at about the same rate" (pp. 40 -41).

More Info

NOAA-ESRL GMD Global CO₂

NOAA-ESRL GMD NOAA-ESRL calculation of global averages

NOAA-ESRL GMD Cooperative Air Sampling Network

SkS CO2 Comparison Chart | Mauna Loa vs. Global Average

SkS CO₂ Comparison Chart | Mauna Loa, Alaska, Samoa, South Pole

Reference

Volk, T. (2008). CO₂ rising: The world's greatest environmental challenge (2010 paperback ed.). Cambridge, MA: MIT Press.

Charts

Charts for Mauna Loa CO₂

Below are two NOAA charts and three Scripps charts. Each chart shows changes in CO2 concentrations at different time scales--from hourly to seasonally. These charts all use averages of readings at the Mauna Loa Observatory in Hawaii that started in March 1958.

NOAA Recent Monthly CO₂ Averages

Source Graphic NOAA-ESRL [web + png + pdf]