A recent study revealed an unexpected impact of CO2 on trees that could change how we understand the response of forests to climate change.
Scientists discovered that the common oak increases its temperature when exposed to higher levels of carbon dioxide.
This finding, made in the United Kingdom, raises new questions about the health of ecosystems.
The unexpected impact of CO2 on oaks
The study, published in the journal Global Change Biology, showed that the canopies of the common oak (Pedunculate oak) increased their average temperature by 1.3 degrees under elevated CO2 conditions.
Sensors recorded 22.8 °C compared to 21.5 °C in normal air.
This is a significant difference for the thermal balance of the trees.
“The differences between the canopy and the air become much more extreme,” the researchers explained.
An experiment that discovered how trees heat up
The pioneering study was conducted after analyzing three years of data at the Birmingham Institute of Forest Research.
Experts installed high-precision thermal cameras in an ancient forest in Staffordshire.
They applied the FACE system, which releases CO2 from the ground to recreate future atmospheric conditions.
The area was divided into sectors with elevated CO2 (150 parts per million extra) and control zones, monitored over three summers.
As a conclusion, they discovered that the oak canopies with more CO2 could not cool down the same.
In these cases, the trees close their stomata, small openings in the leaves, and limit transpiration and, therefore, natural cooling.
“The difference with the air near the ground was much greater in the CO2 areas, especially on the hottest days,” the scientists noted.
Additionally, over time, the leaves under excess CO2 became thicker, which favored heat accumulation.
This small change had a big impact on the canopy microclimate, the highest part of the forest.
The results were repeated even with good humidity levels, indicating a physiological response and not just a climatic one.
“If the trend continues, these oaks will face extreme heat waves much more often than before,” the experts warned.
Among them are William Hagan Brown, Sophie Fauset, and Emanuel Gloor, from the universities of Plymouth, Birmingham, and Leeds.
Why the impact of CO2 on trees worries scientists
The impact of CO2 on trees not only affects oaks but also the ability of forests to regulate the climate.
Researchers warned that current climate models do not include what happens in the canopies, where heat accumulates more rapidly.
They recommended updating forest prediction models and expanding studies to more species and ecosystems to assess how future forests will behave.
Experts agreed that understanding the impact of CO2 on trees is essential to anticipate the effects of climate change.
Although the study focused on a single species, the results point to a global trend.
It is that more CO2 does not always mean stronger trees, but rather systems more vulnerable to heat.
