The claim: Human-generated CO2 contributes insignificantly to climate change
The latest United Nations Intergovernmental Panel on Climate Change report was released in August, documenting dangerous, human-driven changes to Earth’s climate systems and predicting still more to come.
Though the report was described as a “code red for humanity” by UN Secretary-General António Guterres, a years-old claim soon resurfaced on social media claiming that humanity’s CO2 emissions are too minute to impact climate.
A version of the claim in the form of a graphic titled “How climate alarmists use numbers to deceive” was posted to Facebook on Sept. 19 and received hundreds of shares. The graphic also accuses the Environmental Protection Agency of publishing a misleading pie chart that “exaggerates CO2’s role as a greenhouse gas.”
“SCIENTIFIC FACT: Man-made CO2 constitutes only 0.1 to 0.2% of atmospheric greenhouse gases. It is a small contributor to global temperature, and climate,” concludes the post.
Subscribers receive special access Click here to sign up for our fact-check text chat
USA TODAY reached out for comments from social media users.
Human produced CO2 is changing Earth’s climate
Josh Willis, a climate scientist at NASA’s Jet Propulsion Laboratory, told USA TODAY it’s a logical fallacy to assume a proportionally small amount of a substance cannot have a large impact on a system.
“It’s a commonly used technique to confuse people,” he said, pointing out that, for example, minute amounts of arsenic can kill an adult.
Willis said that CO2 from humans is changing the Earth’s climate.
Carbon dioxide is an essential part of the Earth’s biological and atmospheric cycles. Carbon dioxide is not only produced by burning fossil fuels. It can also be expelled by animals or volcanic activity, as an example.
Once expelled, carbon dioxide gets absorbed or sequestered again, in forests, grasslands, bogs, the ocean and other “carbon sinks,” completing the cycle.
While in the atmosphere, carbon dioxide and other greenhouse gases trap heat, creating a habitable planet with stable, warm temperatures. This phenomenon is commonly known as the “greenhouse effect”.
The problem is that humans are now facilitating the release of more carbon dioxide into the atmosphere than was previously cycling, while at the same time destroying sinks, such as forests. This is causing carbon dioxide to accumulate in the atmosphere in amounts unprecedented for hundreds of thousands of years.
The amount of carbon dioxide in our atmosphere is proportionally less than that of other gases like water vapor. Even smaller is the amount that humans produce.
But carbon dioxide behaves differently from other gases. And multiple lines of evidenceIt is enough to cause the climate scientists to document the changes.
Water vapor and CO2 behave differently in the atmosphere
Although the social media post correctly states that water vapor can outweigh CO2 in the atmosphere it is incorrect to claim that CO2 is not significant.
Willis said that this “is an old legend”. “This one is a fact.” debunked Many times.”
The effect of CO2 on atmosphere is not affected by the fact there is more water vapor than CO2.
CO2 and water vapor both contribute to the “greenhouse effect” that warms the Earth and makes it habitable. They play different roles. Climate change is caused by increased CO2 levels. However, climate change is caused by higher water vapor levels.
At a given average temperature, average water vapor levels in the atmosphere remain relatively constant. Fluctuations last only a few hours because water condenses or rains from the atmosphere. Susan SolomonUSA TODAY was informed by Professor Charles Sullivan, an atmospheric chemist from the Massachusetts Institute of Technology in an email.
In a warmer atmosphere, more water accumulates before it rains out. Therefore a warming atmosphere will see an increase in stable water vapor, which will, in turn, exacerbate warming.
However, for this to occur in the first place, the Earth’s atmosphere would already have to be warming up. That is what’s happening, and it’s because of heat trapped by elevated human CO2 emissions.
Willis said that water vapor is produced when the planet heats up. Unlike CO2, “humans don’t control the amount of water in the atmosphere – it’s a reaction to how warm the planet is.”
Post misrepresents EPA pie chart
After claiming that an EPA chart on the subject is misleading, the post incorrectly concludes that CO2 is insignificant.
The unlabeled pie chart shows percentages for carbon dioxide, methane, nitrous oxide and fluorinated gases.
“No mention is made that this chart includes only ‘man-made’ greenhouse gases,” reads the accompanying text.
The text and image in the post are dated 2014, and USA TODAY was unable to find the exact pie chart pictured in the Facebook post. But the style and content match a pie chart found on the EPA’s Inventory of U.S. Greenhouse Gas Emissions and Sinks report webpage.
The current version of this chart is labeled, “Overview of U.S. Greenhouse Gas Emissions.” It doesn’t explicitly state the chart shows only emissions caused by humans, but elsewhere on the page the report notes that the topic is “total greenhouse gas emissions for all man-made sources in the United States.”
The post also states, “By excluding water vapour, this chart can be very deceptive and exaggerates the role of CO2 as a greenhouse gas.”
The chart shows only the relative amounts of various man-made greenhouse gasses that are emitted in America. Nowhere on the page does it state that the chart is intended to depict the role or the importance of each type of gas in the greenhouse effect or climate change.
USA TODAY previously refuted a claim that a similar waterline was shown in photos of a beach taken many years apart. prove that climate change isn’t real. USA TODAY found that a video purporting as a show also showed the same thing. climate activist Greta ThunbergThe denial of the existence a climate crisis was altered.
Our rating: False
Based on our research, it is false to claim that human-made carbon dioxide is a small contributor to climate change. Though human-generated CO2 typically comprises a smaller proportion of atmospheric greenhouse gases than water vapor, research has shown unequivocally that it has a large impact and is changing Earth’s climate.
Our fact-check sources:
- AFP, Oct. 1, Misleading posts downplay human role in climate crisis
- Scientific American, November 30, 2009. 7 Answers to Climate Contrarian Nonsense
- Skeptical Science, accessed November 25, How substances in trace amounts can cause large effects
- Skeptical Science, accessed November 25, How do human CO2 emissions compare to natural CO2 emissions?
- Josh WillisPhone interview with USA Today, November 23,
- Josh WillisNovember 22, Email exchange with USA TODAY
- Susan SolomonEmail exchange with USA TODAY, Nov. 23
- EPA, accessed Nov. 22 Inventory of U.S. Greenhouse Gas Emissions and Sinks
- USA TODAY, Aug. 9 ‘Code red for humanity’: UN report gives stark warning on climate change, says wild weather events will worsen
- United Nations, Aug. 9 Secretary-General Calls Latest IPCC Climate Report ‘Code Red for Humanity’, Stressing ‘Irrefutable’ Evidence of Human Influence
- IPCC, Aug. 9, Climate change widespread, rapid, and intensifying – IPCC
- USA TODAY, June 23, Fact check: Viral video doctored to change Greta Thunberg’s remarks on climate crisis
- USA TODAY, Apr. 23, Fact check: Photos show no change in sea level over 99 years but don’t disprove climate change
- Postgraduate Medical Journal, July 1,2003 Acute and chronic arsenic toxicity
- American Chemical Society, accessed Nov. 26, It’s Water Vapor, Not the CO2
- Climate.gov, Aug. 14, 2020, Climate Change: Atmospheric Carbon Dioxide
- Skeptical Science, accessed November 25, Explaining how the water vapor greenhouse effect works
- EPA, accessed Dec. 1 Overview of Greenhouse Gases
Thank you for supporting our journalism. You can subscribe to our print edition, ad-free app or electronic newspaper replica here.
Facebook grants part of our fact-checking work.