Improved air quality could increase sunlight accessible to plants, enhance carbon sequestration: Study
Washington, DC, US: Air quality would improve if pollution from aerosol particles were reduced. It may also improve plants' ability to extract carbon dioxide from the atmosphere and alleviate climate change by increasing the quantity of sunlight available to them.
A Carnegie-led team lead by Liyin He, Lorenzo Rosa, and Joe Berry utilised satellites to evaluate photosynthetic activity as well as aerosol pollution across Europe, revealing that plants capture more carbon on weekends when industrial production is reduced and fewer people commute.
Their findings are published by the Proceedings of the National Academy of Sciences.
Plants have a special ability, called photossynthesis, by which they convert the Sun's energy into chemical energy. To accomplish this, they take in carbon dioxide from the air and fix it into carbohydrates and fats.
This everyday process is a huge help in the fight against climate change caused by human activity. Plants pull some of our carbon pollution out of the atmosphere and retain it as a biological matter, preventing it from contributing to global warming.
"However, this can be diminished by poor air quality caused by aerosols, tiny particles that are spewed into the atmosphere when we commute and burn fossil fuels or wood," He explained. "They have negative effects on air quality, which impacts human health. They can also scatter or absorb sunlight, which would affect a plant similarly to being stuck in the shade."
Previous work has shown that aerosol pollution can suppress agricultural crop yields by as much as 20 percent.
The research team--which included David Lobell and Yuan Wang of Stanford University; Yi Yin, Yitong Yao, and Christian Frankenberg of Caltech; and Russell Doughty of the University of Oklahoma--used the TROPOspheric Monitoring Instrument (TROPOMI) on board the Copernicus Sentinel-5 Precursor satellite to make measurements of photosynthetic activity in Europe.
Because one step of the photosynthetic process releases fluorescence, it can be seen from space and measured by satellites--a game-changing research method that Berry and Frankenberg played a central role in developing about a decade ago, along with collaborators from Caltech.
The researchers correlated their photosynthesis findings with aerosol measurements taken by the Visible Infrared Imaging Radiometer Suite and used modeling to understand the relationship.
"We focused on Europe due to an established pattern of human activity throughout the week as compared to other regions," Rosa said. "Additionally, many European ecosystems are already experiencing negative effects from climate change and European countries have set ambitious goals for cutting carbon pollution."
Their work showed a weekly cycle of photosynthetic activity, which peaked on the weekend and diminished during the week, the exact inverse of the patterns of aerosol pollution. They also found a similar pattern during COVID-19 lockdowns when people were sheltering at home instead of commuting.
If particulate pollution could be curtailed throughout the week, maintaining weekend levels of photosynthetic activity all the time, it would remove between 40 and 60 megatons of carbon dioxide from the atmosphere and trapping it in biological matter. It would also increase agricultural productivity without increasing the amount of land used for growing crops.
"These findings have major policy implications for European governments who are working on a variety of systems to capture about 500 megatons per year of carbon dioxide out of the atmosphere and store it," Rosa concluded. "Our work shows that improving air quality could also help meet climate goals."
