Carbon dioxide helps plants grow. That doesn’t mean more of it is good for the planet
Wheat grows in a field near Blankenburg am Harz, Germany, Monday, July 31, 2023. A video circulating online claims excess carbon dioxide is good for crop growth in an attempt to discredit efforts to tackle climate change. Excess carbon dioxide does increase growth in some crops, but it also decreases their nutritional value and has other negative impacts on the planet. (AP Photo/Matthias Schrader)
CLAIM: Carbon dioxide is good for crop growth, so efforts to remove it from the atmosphere will destroy the planet.
AP’S ASSESSMENT: False. Excess carbon dioxide does increase growth in some crops, but it also decreases their nutritional value and has other negative impacts on the planet, such as increasing droughts and fires through climate change. Overall, the negatives far outweigh any benefits, experts say. Additionally, researchers are only looking at bringing CO2 levels down to those from a few decades ago.
THE FACTS: A video circulating online is misrepresenting research around crop growth and carbon emissions in an attempt to discredit efforts to tackle climate change.
In the video, a narrator points to a 2022 story from NPR titled “Stopping climate change could mean sucking carbon from the air. He then shows a clip from a natural gas company that supplies supplementary carbon dioxide to greenhouses to help grow tomatoes.
He also highlights a line from a study published by The Lancet in 2019, reading: “Higher CO2 concentrations increase photosynthesis in C3 plants (eg, wheat, rice, potatoes, barley), which can increase crop yields.”
“So if we suck all the carbon out of the air, we’re almost going to destroy the planet. Because these plants need carbon dioxide in order to grow,” the narrator concludes.
But experts — including the authors of the study cited in the video — say this is a fallacy.
For starters, scientists are not seeking to remove “all” CO2 from the air, just to bring it down to earlier levels.
“The intent of scrubbing CO2 from the air is not to remove all the CO2 of course but rather to keep CO2 from increasing so rapidly as we move to a decarbonized economy,” said Phil Robertson, an ecosystem science professor at Michigan State University. “That will stabilize temperatures to historical norms which will be much more advantageous for crop growth than any CO2 fertilization effects.”
Additionally, the video misrepresents the benefits of increased carbon dioxide to some plants by ignoring the downsides.
“Carbon dioxide is plant food. But they’re missing all the nuance,” said Kristie Ebi, a co-author of the Lancet study and a professor of global health at the University of Washington’s Center for Health and the Global Environment.
The key point of the study was that while a higher concentration of carbon dioxide did increase plant growth in 85% of plants, it ultimately lowered their nutritional value, which is not a worthwhile trade-off for the planet, Ebi said. “There’s about 830 million people in the world who are food insecure. There’s about 2 billion that are micronutrient deficient,” said Ebi.
The clip of tomatoes being grown in a greenhouse in the video on social media is a controlled environment where temperature, water and nutrients are optimized for plant growth, but it’s more complicated in outside crop fields, experts explained.
Additionally, not all plants see the same increase in growth from additional carbon dioxide — and it depends where in the world they are grown, said Jonas Jagermeyr, an associate research scientist at Columbia University’s Center for Climate Systems Research. For instance, wheat can benefit from higher CO2 levels than corn can. “However, if wheat was grown in the same regions maize is currently grown (i.e., across tropical and subtropical regions as well as mid-latitudes), it would also face substantial negative impacts,” he said.
More importantly, the increasing amount of heat-trapping carbon dioxide and other greenhouse gases being released by humans into the atmosphere has led to climate change, which has all sorts of other negative impacts on the planet that vastly outweigh any benefits from higher crop yields.
“Heatwaves, droughts, forest fires as we see raging now, and all these other impacts associated with climate change would impact society much more than you would see benefits from slightly higher carbon now,” said Jagermeyr, who also studies food security at the NASA Goddard Institute for Space Studies.
Carbon dioxide levels in the atmosphere are the highest they’ve been in more than 4 million years, and are rising so that each year is higher than the last.
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This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.
