Trees May Absorb More CO2 to Help Mitigate Climate Crisis, New Modeling Suggests

Trees and other plants are known for their air purifying capabilities, providing oxygen to the millions of species on our planet. Planting more trees and preserving the ones we have has been one of the strategies being used to help mitigate the effects of the climate crisis.

A new study using more realistic modeling suggests that plants may be capable of absorbing even more carbon dioxide produced by human activities than previously estimated.

However, the researchers emphasized that their findings do not mean governments can slow down the reduction of carbon emissions in the fight against climate change, a press release from Trinity College Dublin said.

Plants absorb carbon from the atmosphere and convert it into sugars used for metabolism and growth through the process of photosynthesis.

“Plants take up a substantial amount of carbon dioxide (CO2) every year, thereby slowing down the detrimental effects of climate change, but the extent to which they will continue this CO2 uptake into the future has been uncertain,” said lead author of the study Dr. Jürgen Knauer of the Hawkesbury Institute for the Environment at Western Sydney University, according to the press release. “What we found is that a well-established climate model that is used to feed into global climate predictions made by the likes of the IPCC predicts stronger and sustained carbon uptake until the end of the 21st century when it accounts for the impact of some critical physiological processes that govern how plants conduct photosynthesis.”

Scientists have historically been unclear on how the carbon uptake benefits provided by vegetation will respond to changes in temperatures, rainfall and carbon dioxide levels as the climate crisis progresses. For instance, more extreme heat and droughts might significantly weaken the capacity of terrestrial ecosystems to act as carbon sinks.

“We accounted for aspects like how efficiently carbon dioxide can move through the interior of the leaf, how plants adjust to changes in temperatures, and how plants most economically distribute nutrients in their canopy. These are three really important mechanisms that affect a plant’s ability to ‘fix’ carbon, yet they are commonly ignored in most global models,” Knauer said.

The study, “Higher global gross primary productivity under future climate with more advanced representations of photosynthesis,” was published in the journal Science Advances.

The new modeling looked at a climate scenario with high emissions in order to test how the carbon uptake of plants would respond to worldwide climate change until 2100, the press release said.

The research team examined versions of the model with varying complexities and realistic depictions of plants’ physiological processes. The most simplistic version did not take into account the three essential physiological mechanisms of photosynthesis, but the most complicated version took all three into account.

The researchers found that the more complex models consistently predicted greater increases in the carbon uptake of vegetation across the planet. They found that the processes reinforced each other, as they would in the real world, strengthening their effects when combined.

“Because the majority of terrestrial biosphere models used to assess the global carbon sink are located at the lower end of this complexity range, accounting only partially for these mechanisms or ignoring them altogether, it is likely that we are currently underestimating climate change effects on vegetation as well as its resilience to changes in climate. We often think about climate models as being all about physics, but biology plays a huge role and it is something that we really need to account for,” said Silvia Caldararu, an assistant professor in Trinity’s School of Natural Sciences who was part of the research team, in the press release.

Caldararu went on to say that the findings of the study could help scientists better assess potential solutions to the climate crisis found in the natural world.

“These kinds of predictions have implications for nature-based solutions to climate change such as reforestation and afforestation and how much carbon such initiatives can take up. Our findings suggest these approaches could have a larger impact in mitigating climate change and over a longer time period than we thought,” Caldararu said. “However, simply planting trees will not solve all our problems. We absolutely need to cut down emissions from all sectors. Trees alone cannot offer humanity a get out of jail free card.”