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Planting more trees to absorb carbon dioxide might not be the go-to solution to resolve the impact of climate change, according to a new study.
A research team recently found evidence that global photosynthesis levels have slowed down in recent decades and plants are having a harder time absorbing CO2 from the atmosphere, New Scientist reported.
Photosynthesis is the chemical reaction that plants use to convert carbon dioxide and water into carbohydrates. Scientists have assumed that a rise in the greenhouse gas would lead to plants sucking up more CO2 for their photosynthetic process.
However, only a few studies have explored this theory.
Researcher Jingfeng Xiao and his colleagues examined ground measurements from 1982 to 2016 using sensors placed worldwide. These sensors track changes in CO2 and water vapor levels in different environments, such as forests and savannahs.
Using satellite images, they estimated plant growth in different locations and then applied machine learning to combine these datasets, expanding the fluctuation measurements to a global scale.
The findings showed that, on average, increases in global photosynthesis levels have slowed down since 2000, despite rising amounts of CO2 in the atmosphere.
The team explained that this could be because of a rise in the vapor pressure deficit, which leads to increased water evaporation from plants – known as transpiration.
While more transpiration usually supports plant growth, too much water loss can cause leaves to close their pores and hinder photosynthesis.
Still, the authors and other scientists cautioned that further research is needed, adding that there are a number of uncertainties about their measurement model and results.