Northern Hemisphere heatwaves could be up to 5°C hotter than previously estimated, according to a new research by Australian scientists, because plants’ response to increased levels of carbon dioxide has been incorrectly assessed.

The paper published in Nature Scientific Reports this week found that the pores on plants that take in carbon dioxide and release water vapour – stomata – will not need to open as much in high carbon dioxide environments, meaning they will also release less water vapour, which provides an evaporative cooling effect.

“There’s less water vapour being lost so you have a net warming effect,” Murdoch University lecturer and lead author Jatin Kala was reported as saying by Fairfax.

“These more detailed results are confronting but they help explain why many climate models have consistently underestimated the increase in the intensity of heatwaves and the rise in maximum temperatures when compared to observations.”

However, the results could not be applied to the Southern Hemipshere, and Dr Kala said they did not have an observation of how Australian plants would respond to rising CO2 levels.

The CSIRO, which is now looking to cut climate modelling staff, developed the model used to conduct the research.

“If the CSIRO was not around to support and maintain this model, none of this work would have happened,” Dr Kala said.

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