Plants release up to 30 per cent more CO2 than previously thought
New research suggests plants could be releasing more carbon dioxide into the atmosphere than previously thought.
A study involving the Australian National University, Western Sydney University, and centres around the world has found plants release more carbon dioxide through their respiration.
And as global temperatures rise, scientists say the output of carbon dioxide by plants will accelerate.
During daylight hours, plants take in carbon dioxide and release oxygen through photosynthesis, and at night only about half that carbon is then released through respiration.
However, plants still remain a net carbon sink, meaning they absorb more than they emit .
“Currently, around 25 per cent of carbon emissions from the use of fossil fuels is being taken up and stored by plants, which is good, as it helps reduce the concentration of greenhouse gases in the atmosphere,” ANU researcher Owen Atkin said.
“Our work suggests that this positive contribution of plants may decline in the future as they begin to respire more as the world warms.”
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Professor Atkin said plants were previously thought to respire five to eight times the carbon that is produced by human activity.
However, the new findings suggested that number could be much higher.
“Each year the burning of fossil fuels releases around 5 to 8 billion tons of carbon … so the respiration by plants is somewhere approaching 11 times that in our new estimate,” he said.
“That’s an enormous flux.
“What will happen in the future will be that those rates of carbon released by plants will increase as the world gets warmer, and it will have an impact on how much carbon is stored in vegetation, how much accumulates in the atmosphere in the future.”
The study examined about 1,000 plant species in a range of climate extremes, to determine how much carbon dioxide is released in various scenarios.
“This will have fairly substantial implications for our ability to model carbon flows between landscapes and the atmosphere, and ultimately how much carbon dioxide accumulates in the atmosphere,” Professor Atkin said.
Researchers said plants could also see a declining ability to absorb carbon dioxide currently in the atmosphere through photosynthesis, and that carbon flow models and budget projections would need to be altered in response to the findings.
/Editor’s note November 22, 2017: This story was amended to emphasise that plants are a net carbon sink and they absorb more carbon dioxide than they emit. The ABC acknowledges a previous version of the story was unintentionally misleading and did not represent the research findings in an accurate context./
Posted 17 Nov 201717 Nov 2017, updated 21 Nov 2017