Together with colleagues from several U.S. institutions, a group of Earth scientists at the Chinese Academy of Agricultural Science’s Grassland Research Institute have discovered evidence that the rise in photosynthesis rates worldwide brought on by the increase in carbon dioxide has been significantly slowed.
The team analyzed variations in worldwide photosynthetic rates over the course of several decades in their study, which was published in the journal Science.
During photosynthesis, plants convert CO2 and water into carbohydrates and release oxygen, therefore they are considered to be carbon sinks.
Previous studies have demonstrated that plants have benefited from the rise in carbon dioxide levels in the atmosphere over the past century by accelerating photosynthesis and removing more carbon from the atmosphere.
The net effect has been a brake on global warming. In this new study, the research team discovered evidence that increasing atmospheric CO2 has caused the atmosphere to become drier, which has slowed the pace of rise in worldwide photosynthesis.
The researchers examined data gathered by ground monitors around the globe between the years of 1982 and 2016 to understand more about the rate of photosynthesis on a global scale. Environmental information are gathered by these sensors, including the CO2 and water content of the air.
The team also collected satellite images of regions covered by foliage. The photographs were then used to train a number of machine learning programs to detect subtle changes, such the hues of leaves that indicate photosynthesis rates.
The scientists then used the obtained data to build models that graphically represented changes in global synthesis rates from 2000 to the present. They then used the models to predict future changes.
The scientists discovered that as CO2 levels increased over the past century, worldwide rates of photosynthesis increased proportionally. But beginning in 2000, things started to alter. As the earth gets hotter and drier, photosynthesis rates have started to slow down and may soon stop rising entirely.
