Plants making hotter heatwaves

March 22, 2016

Dr Jatin KalaNew research has identified plants as playing a key role in increasing the temperature of future global heatwaves.

A climate scientist at Murdoch University has discovered that heatwaves from Europe to China are likely to be more intense and result in maximum temperatures that are 3°C to 5°C warmer than previously estimated.

In a paper for Nature Scientific Reports, Dr Jatin Kala from the School of Veterinary and Life Sciences along with collaborators from the University of New South Wales, looked at data from 314 plant species across 56 field sites.

They found that some species lose less water to the atmosphere than had been previously assumed.

This will result in temperature increases by the middle of the century which are more than 50 per cent higher than the rises forecast by the IPCC, the scientists said.

“We often underestimate the role of vegetation in extreme temperature events as it has not been included in enough detail in climate models up until this point,” said lead author Dr Kala.

“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.”

To get their results, the researchers investigated stomata, small pores on plant leaves that take in carbon dioxide and lose water to the atmosphere.

Most climate models assume all plants trade water for carbon in exactly the same way, ignoring experimental evidence showing considerable variation among plant types. By not accounting for these differences, models have likely over-estimated the amount of water lost to the atmosphere in some regions.

If plants release less water, there is more warming and a consequent increase in heat wave intensity.

The biggest temperature changes were projected to occur over needleleaf forests, tundra and agricultural land used to grow crops, Dr Kala said.

His study is the first time the water-use strategies of plant species have been incorporated into a global climate model. It will have a significant impact on the development of climate models around the world.

The study brings together observations by ecologists, theory from biologists, physics from land surface modellers and climate science.

According to Dr Kala, research of this magnitude can only be achieved through the strong institutions Australia has built up over time.

“These institutions have enabled us to develop a world-leading climate model, unique observation systems and computational infrastructure that has far reaching benefits,” said Dr Kala.

CSIRO, the Bureau of Meteorology and the ARC Centre of Excellence for Climate System Science developed the Australian Community Climate and Earth System Simulator (ACCESS) model used in this study.

ARC Discovery funding enabled ecological researchers at Macquarie and Western Sydney Universities to put together the plant observations from around the world.

At the same time the National eResearch and Collaboration Tools and Research Project (NECTAR) was key to managing the data produced by the ACCESS model. The model itself used National Computational Infrastructure supported and resourced by the National Collaborative Research Infrastructure Strategy.

Dr Kala's paper can be viewed here.

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