co2 earth co2 records banner photo by peter boccia




Mauna Loa* CO2 Levels

in recorded human history
(and millions of years before that) 



Scripps MLO 


428.59 ppm

Apr 26 2024

NOAA Daily

428.63 ppm

Apr 26 2024



427.94 ppm

Apr 21 -27 2024




426.91 ppm

Jun 2024


425.22 ppm**

Mar 2024



 418.56 ppm



 416.45 ppm


monthly data averaged

* Mauna Loa record includes CO2 measurments at Maunakea site in 2022-2023  
** Record high for the institution, not for CO2 measurements at Mauna Loa


Marking the latest CO2 records is not an act of celebration, but of bearing witness.  

The achievements are a sobering reminder of the chemical changes that we humans are collectively making to the atmosphere--changes with disruptive impacts that affect every living being in the biosphere.  When a new record is reached, it is is marked here with an invitation for people to take notice, reflect on the transformation that is going in the wrong direction, and resolve to reverse these trends.

Reversing the trend is not something that any one person can achieve on their own.  But individuals and groups can build on this CO2 Earth initiative by taking steps that help make the CO2 indicator for planetary health as ubiqutious as our stock market updates and weather reports.  Consider sharing the CO2 Earth updates and records with people and groups that are part of your information-sharing circle.  



A New Daily High Each Year

The graphic below from Teem Earth partner @NumberLens presents NOAA CO2 readings from1999 to 2020 to show the progression of the seasonal peak for daily CO2 readings at Mauna Loa.  It shows that CO2 levels usually peak in April or May, a phenomena discovered by Charles David Keeling in the late 1950s and early 1960s when he began what became the world's longest-running, high preceision record of direct measurements of CO2 in background air.  Read about this in Keeling's autobiographic science article, Rewards and Penalties of Monitoring the Earth. (Link: Scripps CO2 Program

2020 06 01 dly co2 high since 1999 mlo noaa



*Atmospheric CO2 is higher now than at any time in the past 200,000 years of human history.  In fact, studies of past CO2 levels have accumulated evidence of CO2 levels being lower than 400 ppm for the past 23 million years.  That makes the CO2 records on this page the highest in human history plus a period that's a hundred times the 200,000 years that homo sapiens have graced the earth.   But the current elevation of CO2 levels is just one side of the problem.  The other is the speed of the changes in atmospheric composition--more than a hundred times the speed of change before the Industrial Revolution.  Living species and ecosystems adapt to change, but fewer can endure when the speed of change is too fast.  To slow the speed of temperature change and return to stable and safe levels, turning down the atmospheric thermostat is job 1.   Mostly, that is achieved by getting emissions from fossil fuel burning as close to zero as possible, and as soon as possible. 



Related Links

Science Daily Jun 2020 | Today's atmospheric CO2 levels greater than 23 million-year record 

Geology 2020 | A 23 m.y. record of low atmospheric CO2  

CO2 Earth | Daily CO2

CO2 Earth | CO2 Proxy Data

CO2 Earth | CO2 Acceleration

CO2 Earth | Examples of CO2 Media Broadcasts

CO2 Earth | CO2 for Print