Plants refuse to absorb CO2 in a warming climate

You learned in school that plants take nutrients and water from the soil, energy from the sun and CO2 from the atmosphere. This process results in emissions of oxygen that we breathe so nicely. However, scientists from the University of Queensland say that this is slowly changing – as the world is warming up, the rate at which plants in certain regions can absorb carbon dioxide is declining.

In certain regions plants will start absorbing less CO2 as the global temperatures continue to rise. Image credit: Bob Linsdell via Wikimedia (CC BY 3.0)

Australian scientists were taking direct measurements of plant absorption of CO2 in subtropical coastal ecosystems for three years. They found that there is an optimal temperature for photosynthetic production and it was sometimes exceeded in those particular regions in eastern Australia. That optimal temperature is etween 24.1 and 27.4 degrees Celsius, but it depends on the area. As you might imagine, in Australia that 27.4 degrees mark is crossed regularly – temperatures exceeded this range between 14 and 59.2 % of the time of the monitoring period.

What does it mean? Well, plants in that area are just not as good at absorbing carbon dioxide as they otherwise would if the temperatures were a little lower. And this is unbelievably worrying. Scientists measured the rate at which photosynthesis was occurring and found that beyond the optimal range of temperature the ability for plants to appropriate carbon falls off a cliff. This is particularly important in the context of climate change, because CO2 is a greenhouse gas and we are trying to reduce the concentrations of it from the atmosphere. If plants are not as efficient at doing that, climate change might accelerate.

This might cause a domino effect, making the situation worse and worse. The increase of CO2 will lead to a more rapid climate change. This will shift the frequency of the rain – in some areas it will be more frequent, while in others, such as the subtropics and Mediterranean climate zones it is likely to decrease. Because there will be less rain, green plants are also going to reduce, making it even more difficult for them to absorb CO2. Hamish McGowan, lead author of the study, said: “Much of the current modelling doesn’t capture these nuances – the ongoing sequestered carbon we were counting on in subtropical coastal regions might not come to pass. There’s an urgent need to extend our research to other biomes so that the effects of temperature and moisture availability on carbon sequestration by photosynthesis can be quantified”.

The world leaders are still arguing about emissions and green politics. Time is ticking. Once the first domino tile drops, it will be increasingly difficult to achieve a positive change. Scientists also have to put more effort into understanding photosynthesis and how it changes according to the climate.


Source: University of Queensland

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