Plants in Europe tend to carry out more photosynthesis on weekends, likely due to lower air pollution levels.
Photosynthesis is the process by which plants harness energy from the sun and convert carbon dioxide and water into sugar.
Given the increasing air pollution from sources such as wildfires, dust, and human activities, Liyin He and her team at the Carnegie Institution for Science in California sought to examine the impact of air quality on photosynthesis.
The researchers analyzed satellite data on the amount of light emitted by chlorophyll in plant leaves, which correlates with photosynthesis levels, across Europe from 2018 to 2021. They then compared this data with satellite measurements of air pollution during the same period.
Their analysis revealed that photosynthesis rates increased when levels of aerosol pollution – which includes dust, smoke from wildfires, and human-generated pollution – were lower. Aerosols can obstruct sunlight from reaching the Earth’s surface, thus impeding photosynthesis. Conversely, reduced aerosol pollution allows more sunlight to reach plant leaves.
The team observed higher rates of photosynthesis during weekends in 64% of Europe, attributing this to reduced traffic and industrial activities, leading to cleaner air. Conversely, weekdays showed higher aerosol levels, resulting in a noticeable weekly cycle.
Notably, in 2020, aerosol pollution decreased significantly due to the COVID-19 pandemic. Consequently, plants exhibited increased productivity throughout the week, not just on weekends.
These findings suggest that reducing aerosol levels, particularly from transportation and industrial processes, could enable plants to capture and store more carbon. In fact, He and her colleagues estimated that if aerosol pollution levels returned to the levels seen during the pandemic’s peak, plants could remove an additional 41 million tonnes of CO2 from the atmosphere annually.
He emphasizes that improving air quality not only benefits human health but also enhances ecosystem productivity.
Insights
The study’s findings provide significant insights into the relationship between air quality and plant productivity. The observed increase in photosynthesis during weekends due to lower pollution levels highlights the impact of human activities on plant ecosystems. Additionally, the substantial reduction in aerosol pollution during the COVID-19 pandemic and its subsequent effect on plant productivity underscores the critical role of human behavior in shaping environmental conditions.
