It’s something we all learn in high school biology: plants “breathe in” carbon dioxide and release oxygen. Animals breathe in oxygen and expel carbon dioxide. The only problem is that that isn’t the whole story.
Nothing in nature is 100% clear-cut or efficient. Humans (and other animals) don’t absorb all the oxygen we breathe in, and we add extra gases of our own thanks to the complex chemical reactions that we call “living”.
Similarly, plants don’t absorb all the carbon dioxide they “inhale”. But a new study suggests that they “exhale” a lot more CO2 than previously supposed.
A new study involving ANU and international collaborators has found plants release more carbon dioxide into the atmosphere through respiration than expected.
Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis.
Professor Owen Atkin from ANU said the study revealed that the release of carbon dioxide by plant respiration around the world is up to 30 per cent higher than previously predicted.
So, just how much CO2 do plants release? Once again, nature humbles the human conceit that we are the only creatures capable of changing the planet.
He said the carbon dioxide released by plants every year was now estimated to be about 10 to 11 times the emissions from human activities, rather than the previous estimate of five to eight times.
There are two takeaways from this study that the authors don’t appear to want to discuss out loud.
Firstly, it once again exposes the myth of “the science is settled”. For instance, climate models which presumably factored in an estimate of plant CO2 expiration would likely have been out by about 20% or more. This is just one of the limitations of climate modelling.
But, more importantly, it provides at least one mechanism for a simple fact which has bedevilled the whole “CO2 causes global warming” narrative: the evidence from ice cores shows, in fact, the reverse: higher CO2 levels (at least for the last few hundred thousand years) have tended to come after temperature rises.
“The study shows that as global temperatures increase, the amount of carbon dioxide released through plant respiration will increase significantly,” said Professor Atkin from the Research School of Biology and the ARC Centre of Excellence in Plant Energy Biology at ANU.
“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.
“Our work suggests that this positive contribution of plants may decline in the future as they begin to respire more as the world warms.”
Australian National University
It also suggests that the relationship between climate and CO2 is not the simple one the climate cult would have us believe. It also suggests that the response of the natural world to climate change is more dynamic than they would also have us believe.
But they won’t talk about that out loud.
