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It's not one or the other: CO2 can drive global warming and fertilize plants | Fact check

Kate S. Petersen, USA TODAY
·4 min read

The claim: Greenhouse CO2 supplementation shows climate change is a 'scam'

An Oct. 29 Facebook post (direct link, archive link) shows a large turbine-like object hanging inside of a greenhouse.

"If carbon dioxide is so bad for the planet, why do greenhouse growers buy CO2 generators to double plant growth?" reads text above the image.

The user captioned the post, "Science is hard. #ClimateChangeScam."

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Our rating: False

The use of CO2 in a greenhouse setting does not contradict climate science or show that climate change is a "scam." CO2 is used in greenhouse settings to boost plant growth. Data shows CO2 is also causing modern global warming − and an array of negative consequences − by slowing the escape of heat energy into space.

CO2 can fertilize plants and also drive global climate change

The post is correct that carbon dioxide supplementation is sometimes used to increase photosynthesis and, thus, the growth rates of some greenhouse plants, according to Oklahoma State University Extension. Increasing CO2 accelerates photosynthesis (under certain conditions) because it increases the efficiency of an important enzyme, making photosynthetic reactions faster and more energy efficient, Thomas Bytnerowicz, a climate and plant physiology researcher at the University of Florida, told USA TODAY.

Supplementation can double productivity, but this effect is dependent on other variables.

"Plants may not show a positive response to supplemental CO2 because of other limiting factors such as nutrients, water and light," Oklahoma State University reports. "All factors need to be at optimum levels."

Increasing greenhouse CO2 concentrations too much may also damage greenhouse plants, according to the university.

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But none of this means CO2 isn't causing global warming, and the way CO2 accelerates photosynthesis has little to do with the mechanism by which it is causing modern global warming − a process that has been studied by researchers for more than a century.

Atmospheric CO2 is causing global warming by intercepting heat energy otherwise destined for space and then sending energy in all directions, including back down to Earth, USA TODAY previously reported.

Thus far, greenhouse gases released by humans, such as CO2, have caused Earth's temperatures to rise nearly 2.5 degrees since the late 1800s, according to NASA. The ramifications of this warming include:

When reached by USA TODAY, the social media user said CO2 can't be "bad for the climate" if it promotes vegetation growth.

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This article originally appeared on USA TODAY: False claim greenhouse CO2 shows climate change a 'scam' | Fact check

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