One third of atmospheric CO2 released by humans since 1850s | Fact check

The claim: Antarctica hasn't warmed for over 70 years because humans have only contributed 40 ppm of CO2 to the atmosphere

A Dec. 1 Instagram video (direct link, archive link) shows a headline that reads "Scientists Struggle to Understand Why Antarctica Hasn't Warmed For Over 70 Years Despite Rise In CO2."

The video then pivots to a person saying Antarctic temperatures haven't risen because CO2 only constitutes 400 parts per million (ppm) of Earth's atmosphere and the human contribution to that is only 40 ppm.

The video garnered more than 2,000 likes in less than two weeks.

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Our rating: False

There is significant evidence that Antarctica has warmed within the last 70 years. The concentration of CO2 in Earth's atmosphere is currently about 422 ppm, but humans have contributed about a third of that, much more than 40 ppm, according to researchers.

Humans contribute significant CO2 to the atmosphere as Antarctica warms

The climate in Antarctica varies naturally over time and is different in far-flung parts of the massive continent, researchers told USA TODAY. This, coupled with relatively sparse data, makes it more challenging to document and interpret temperature trends.

However, evidence points to a multi-decade Antarctic warming trend, Mathieu Casado, a paleoclimate and polar meteorology researcher at the Climate and Environmental Sciences in France, told USA TODAY in an email. Based on an analysis of dozens of Antarctic ice cores, Casado's team reported a continental warming trend of around 0.4-0.6 degrees per decade between 1950-2005.

Other studies have also reported warming over the last few decades. Some studies report warming in some regions and cooling in others during different periods of time.

Researchers have reported that Western Antarctica and the South Pole are warming more quickly than the global average.

"The weight of evidence is that most of Antarctica has warmed significantly in the past several decades," Theodore Scambos, an Antarctic researcher at the University of Colorado Boulder, told USA TODAY in an email.

The headline shown in the video is from an article that references a 2020 research paper. In the paper, which examined a specific dataset through 2014, the authors state that Antarctica has not warmed for 70 years. However, other studies have reported Antarctic warming trends beginning prior to 2014.

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The concentration of CO2 in the atmosphere is a bit higher than the post claims − around 422 ppm, according to NASA. Humans have also contributed roughly one-third of this CO2 since the 1850s, Gavin Schmidt, a NASA climate scientist and director of the Goddard Institute of Space Studies, previously told USA TODAY.

This equates to around 140 ppm − significantly more than the 40 ppm the post claims.

In 1850, the concentration of CO2 in the atmosphere was around 280 ppm, according to European Environment Agency data. Scientists can tell the rise to more than 422 ppm was due to human emissions because "carbon produced by burning fossil fuels has a different ratio of heavy-to-light carbon atoms, so it leaves a distinct 'fingerprint' that instruments can measure," NASA reports.

The CO2 and other greenhouse gases that humans have contributed to the atmosphere have caused a significant and well-documented global warming trend, according to NASA.

USA TODAY reached out to the Instagram user who shared the post for comment but did not immediately receive a response.

Our fact-check sources

• Walter Meier, Dec. 10, Email exchange with USA TODAY
• Theodore Scambos, Dec. 11, Email exchange with USA TODAY
• Mathieu Casado, Dec. 9, Email exchange with USA TODAY
• Ella Gilbert, Dec. 10, Email exchange with USA TODAY
• Nathan Gillett, Dec. 10, Email exchange with USA TODAY
• NASA Vital Signs of the Planet, accessed Dec. 9, Carbon Dioxide
• NASA, Oct. 9, 2019, The Atmosphere: Getting a Handle on Carbon Dioxide
• NASA Earth Observatory, Jan. 23, 2009, Antarctic Warming Trends
• NASA, accessed Dec. 11, GISS Surface Temperature Analysis (v4)
• USA TODAY, June 26, 2023, Humans are responsible for a significant amount of CO2 in the atmosphere | Fact check
• European Environment Agency, Sept. 20, Trends in atmospheric concentrations of CO2 (ppm), CH4 (ppb) and N2O (ppb), between 1800 and 2017
• Journal of Climate, Oct. 15, 2019, Sixty Years of Widespread Warming in the Southern Middle and High Latitudes (1957–2016)
• Nature Climate Change, Sept. 7, 2023, The quandary of detecting the signature of climate change in Antarctica
• Nature Climate Change, August 2020, Warming reaches the South Pole
• Nature Geoscience, February 2013, Central West Antarctica among the most rapidly warming regions on Earth
• Nature Geoscience, Oct. 4, Sustained greening of the Antarctic Peninsula observed from satellites
• Carbon Brief, Sept. 13, 2023, Guest post: Ice cores reveal Antarctica is warming twice as fast as global average
• Carbon Brief, June 29, 2020, South pole warmed ‘three times faster’ than global average over past 30 years
• Geophysical Research Letters, Aug. 24, 2022, West Antarctic Surface Climate Changes Since the Mid-20th Century Driven by Anthropogenic Forcing
• Geophysical Research Letters, Aug. 12, 2011, Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods
• Climate Dynamics, Jan. 23, 2011, An assessment and interpretation of the observed warming of West Antarctica in the austral spring
• Science Advances, June 23, 2021, East Antarctic cooling induced by decadal changes in Madden-Julian oscillation during austral summer

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This story was updated to correct a typo.