Plants will absorb 20% more carbon dioxide than predicted by the end of the century, a new study finds, suggesting that climate models are overestimating how quickly the planet will warm.
Trinity College Dublin said its research painted an “unusually rosy picture for the planet” after finding that models did not take into account all elements of photosynthesis.
During photosynthesis, green plants use light energy from the sun to convert carbon dioxide, water and minerals into the sugars needed for growth.
Scientists thought climate change might weaken the process, but the new research suggests that plants can adjust to temperatures, efficiently absorbing carbon dioxide, producing additional nutrients and continuing to thrive.
They found that, on a global scale, the amount of carbon converted during photosynthesis could be up to 68 percent greater by the end of the century compared to the beginning of the century, and 20 percent more than some current models suggest.
Emissions still need to be reduced
Silvia Caldararu, assistant professor at Trinity’s School of Natural Sciences, said: “What our study shows is that ecosystems could absorb more CO2 from the atmosphere than previously thought, which would mean lower concentrations of CO2, therefore a less pronounced increase in temperature.
“So yes, that would give us a little more time to get to net zero. But it’s important to note that we anticipate much of this reduction will occur later in the century, while we need to reduce emissions now, or possibly yesterday.”
Plants absorb a huge amount of carbon dioxide every year, slowing the effects of climate change, but experts are unsure whether this would continue as the climate changes.
In recent years, observations have shown that carbon dioxide uptake by plants is increasing, which is likely driven in part by increased vegetation growth caused by rising carbon.
An increase in plants’ ability to absorb carbon dioxide not only removes it from the atmosphere, but increased growth indirectly reduces the earth’s temperature and mitigates the effects on global climate change.
Although climate modelers have attempted to include estimates for this carbon sink, researchers have found that most models were not complex enough to understand plants’ true resilience to climate change.
The researchers found that under the RCP 8.5 extreme warming scenario, a pathway in which greenhouse gas emissions continue to grow without mitigation, plants would remove a fifth more carbon dioxide from the air than currently expected.
The RCP 8.5 scenario predicts a temperature increase of around 4.3ºC by 2100, in relation to pre-industrial temperatures.
However, the authors warned that terrestrial ecosystems only absorb about a quarter of human emissions, so the extra benefit would increase that figure to about 30 percent.
They said this showed the importance of protecting forests and green areas and implementing plantation schemes.
‘Planting trees will not solve all our problems’
Jürgen Knauer from Western Sydney University, who led the research team, said: “These types of predictions have implications for nature-based solutions to climate change, such as reforestation and afforestation, and the amount of carbon that such initiatives can absorb.
“Our findings suggest that these approaches could have a greater impact on climate change mitigation and over a longer period of time than we previously thought.
“However, simply planting trees will not solve all of our problems. We absolutely need to reduce emissions from all sectors. Trees alone cannot offer humanity a get-out-of-jail-free card.”
Commenting on the research, Professor Simon Lewis, professor of global change science at University College London (UCL), said: “This is a good study, but the interpretation of what this means for future carbon uptake from the atmosphere and for Forests need care.
“Faster-growing trees tend to have shorter lifespans, so it’s possible we could see greater photosynthesis, as this study shows, but without large additional increases in carbon stored in the land.”
Professor Mark Maslin, professor of climatology at UCL, said the results did not change the need to reach net-zero emissions as quickly as possible.
The research was published in the journal Science Advances.