No, CO2 levels in Earth’s atmosphere 150 years ago were not the same as in 2024

What is the claim?

A viral social media post, shared on May 8 in a Facebook group named Climate Con, claims that the CO2 level in the Earth’s atmosphere today is identical to that of 150 years ago. The post states, “CO2 in the atmosphere 150 years ago: 0.04%. And today: 0.04%.” An archived version of the post is available here. 

Screenshot of the post. (Source: Facebook/Modified by Logically Facts)

However, this claim is incorrect. The CO2 level in the Earth’s atmosphere 150 years ago was 288.4 ppm or 0.0288 percent, nearly half of the current level of 0.0426 percent. 

Clear spike after Industrial Revolution

CO2 levels in the Earth’s atmosphere reached a level 50 percent higher than pre-industrial levels for the first time in 2021. According to the National Oceanic and Atmospheric Administration (NOAA), CO2 levels remained consistently around 280 ppm for almost 6,000 years of human civilization before the Industrial Revolution. 

Data on global atmospheric CO2 concentrations from 1700 to 2021 shows a clear spike in carbon dioxide levels:

• By 1960, global atmospheric CO2 concentration had crossed the 300 ppm mark.
• In 2021, CO2 concentrations reached 417 ppm or 0.0417 percent, representing a 50 percent increase over the 1750-1800 average, which was around 278 ppm.
• In 2022, carbon dioxide levels rose to 421 parts per million.
• As of May 2024, the CO2 level has risen to 426.85 ppm.

The graph shows an increase in CO2 levels between 1760 to 2021. (Source: Carbon Brief/Screenshot)

What was the CO2 level 150 years ago? 

The viral post claims that the CO2 concentration 150 years ago, in 1874, was 0.04 percent. However, reliable scientific data shows that between 1870 and 1880, the CO2 levels were below 300 ppm or 0.03 percent. 

According to data published by the Goddard Institute for Space Studies (GISS), NASA, the CO2 concentration 150 years ago, in 1874, was 288.4 ppm, or 0.0288 percent, nearly half of the current CO2 level of 0.0426 percent. 

The data also shows that the CO2 concentration was 285.2 ppm in 1850 and peaked at 391 ppm in 2011. Future predictions suggest that it will increase up to 560 ppm by 2099. 

‘Blatantly false,’ says climate science expert 

Logically Facts contacted Howard Diamond, Climate Science Program Manager at NOAA’s Air Resources Laboratory, who called the claim ‘blatantly false.’ He stated, “Atmospheric CO2 levels in 1874 were at 288 parts per million (0.0288 percent), and today they are nearly 50 percent greater than that and standing at just over 426 ppm (0.0426 percent).”

Diamond also emphasized that CO2 has never surpassed 300 ppm levels for the past hundreds of thousands of years, and fossil fuel burning and the ensuing emissions are the primary reasons behind the recent rapid rise in CO2 levels.  

“In the 800,000-year EPICA (European Project for Ice Coring in Antarctica) ice core record (see attached), the concentration of CO2 never exceeded 300 ppm, and so this rise of 50 percent in atmospheric CO2 over a 370-year period (mostly over the past 100 years) is unprecedented and attributed to the human burning of fossil fuels and the resultant emission of CO2 (coupled with land use changes that have contributed about 5 percent of the problem,” Diamond explained, besides sending us a graph showing the rise in CO2 concentrations in the last 1000 years. 

The change in CO2 levels over the last 1000 years. (Source: Howard Diamond/Screenshot)

“In nature, without human emission of CO2, a rise of 100 ppm of CO2 would take about 20,000 years, and we have risen by that level in about the last 50 years, so that is a rate 400 times greater than what would occur naturally,” he added. 

Social media posts related to CO2 or carbon dioxide have been among the most frequently repeated false or misleading narratives on social media regarding climate change misinformation. Logically Facts has analyzed and debunked various claims connected to carbon dioxide levels in the atmosphere.

The verdict

The CO2 level on Earth 150 years ago was 0.0288 percent, almost half of the current level of 0.0426 percent. The carbon dioxide level in 1874 was 288 ppm, or 0.0288 percent, whereas it currently stands at 426 ppm (0.0426 percent). Therefore, we have marked this claim as false.