Earth's CO2 emissions, including emissions by humans, dwarf Tonga volcano | Fact check

Kate S. Petersen, USA TODAY
·4 min read
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The claim: 2022 Tonga eruption emitted more CO2 than the Earth does in a year

A Dec. 19, 2023, Facebook post (direct link, archive link) shows a person talking about the 2022 eruption of Hunga Tonga-Hunga Ha’apai, an underwater volcano in the South Pacific Ocean.

"When the Tonga volcano erupted in 2022, it emitted enough CO2 to cover the entire Earth's output for an entire year," he says. "So it doesn't matter how many solar panels, milk floats, yogurt pots you recycle, or anything like that."

The post was shared more than 1,000 times in less than three weeks.

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Our rating: False

The 2022 Hunga Tonga-Hunga Ha’apai eruption is estimated to have released significantly less CO2 than is emitted annually by humans or natural processes.

CO2 emissions from human activity dwarf emissions from 2022 Hunga Tonga eruption

Vivienne Payne, a lead scientist for the NASA Carbon Observatory missions − which monitor CO2 levels in the Earth's atmosphere − told USA TODAY that she is not aware of a published CO2 emissions estimate for the 2022 eruption. However, she said it is not possible that it produced the amount of CO2 that humans produce in a year because global atmospheric CO2 levels didn't increase more than usual in 2022.

CO2 produced by human activity has caused the concentration of CO2 in the atmosphere to rise by more than two parts per million every year since 2012. If CO2 emissions from the 2022 Hunga Tonga-Hunga Ha’apai eruption emitted a year's worth of human CO2 emissions, then the increase in atmospheric CO2 should have been significantly higher.

Instead, atmospheric CO2 concentrations grew by 2.17 ppm in 2022, the lowest amount of growth since 2017.

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There are published estimates of sulfur dioxide emissions from the 2022 eruption, and these can be used to roughly approximate CO2 emissions, researchers told USA TODAY.

"I would estimate that the eruption emitted on the order of 2 to 5 million metric tons of CO2," said Simon Carn, a volcanologist at Michigan Technological University who studied sulfur dioxide emissions from the eruption. "This is based on the actual sulfur dioxide emissions measured using satellite data and a reasonable estimate of the ratio of CO2 to sulfur dioxide in the emissions − based on data from other volcanoes."

Jake Lowenstern, chief of the Volcano Disaster Assistance Program at the U.S. Geological Survey, said that based on sulfur dioxide emissions estimates the volcano could have emitted up to around 34 million metric tons of CO2, but the number was likely lower.

Annual CO2 emissions from human activity, such as industry and energy production, are much higher, having reached 36.8 billion metric tons in 2022, according to the International Energy Agency.

"In general, we expect the volcanic emissions worldwide to be at least 100 times smaller than the anthropogenic emissions in any given year," Payne said in an email.

Natural CO2 emissions from all sources dwarf emissions from the Hunga Tonga eruption

Annual natural CO2 emissions from the "entire" Earth also dwarf emissions from the 2022 Hunga Tonga-Hunga Ha’apai eruption. Earth emits and reabsorbs hundreds of billions of metric tons of CO2 annually through natural processes, according to the Global Carbon Budget.

Climate change is occurring because the additional CO2 added by human activity cannot all be absorbed by natural systems. Thus, it accumulates in the atmosphere, slowing the escape of heat into space and causing warming.

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USA TODAY has previously debunked false CO2 emissions claims involving other volcanoes. These include the recent eruption near Grindavik, Iceland, and an eruption of Italy's Mt. Etna, which social media users wrongly claimed had "put more than 10,000 times the CO2 into the atmosphere than mankind has in our entire time on Earth."

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

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This article originally appeared on USA TODAY: Tonga underwater volcano CO2 dwarfed by other emissions | Fact check