Improving air quality can enhance natural carbon sequestration by plants

Reducing pollution caused by aerosol particles will improve air quality. It can also increase the amount of sunlight available to plants, enhancing their ability to remove carbon dioxide from the atmosphere and mitigate climate change.

New work by a Carnegie-led team, including Lin He, Lorenzo Rosa, and Joe Perry, used satellites to measure photosynthetic activity and aerosol pollution in Europe, showing that plants capture more carbon on weekends when industrial production declines. Fewer people move around.

Their findings are published previously Proceedings of the National Academy of Sciences.

Plants have a special ability called photosynthesis, where they convert the sun’s energy into chemical energy. To achieve this, they take carbon dioxide from the air and convert it into carbohydrates and fats.

This daily process is a huge help in the fight against human-induced climate change. Plants pull some of the carbon pollution from the atmosphere and retain it as biological matter, preventing it from contributing to global warming.

“However, this could be diminished by poor air quality caused by aerosols, which are small particles released into the atmosphere when we move around and burn fossil fuels or wood,” he explained. “They have negative effects on air quality, affecting human health. They can also scatter or absorb sunlight, which can affect a plant similarly to being in the shade.”

Previous research has shown that aerosol pollution can reduce agricultural crop productivity by up to 20%.

The research team, which included David Lobel and Yuan Wang of Stanford University; Yi Yin, Weitong Yao, and Christian Frankenberg from Caltech; Russell Doughty of the University of Oklahoma used the TROPOMI Atmospheric Observing Instrument aboard the Copernicus Sentinel-5 Precursor satellite to make measurements of photosynthesis activity in Europe.

Because one step of the photosynthesis process releases fluorescence, it can be seen from space and measured by satellites, a game-changing research method that Perry and Frankenberg played a central role in developing nearly a decade ago, along with collaborators from Caltech.

The researchers linked their photosynthesis findings with aerosol measurements made by the Visible Infrared Imaging Radiometry Array and used modeling to understand the relationship.

“We focused on Europe because of the consistent pattern of human activity throughout the week compared to other regions,” Rosa said. “In addition, many European ecosystems are already experiencing negative impacts due to climate change, and European countries have set ambitious carbon pollution reduction targets.”

Their work showed a weekly cycle of photosynthetic activity, which peaked on the weekend and diminished during the week, the exact opposite of aerosol pollution patterns. They also found a similar pattern during coronavirus lockdowns, when people were sheltering at home rather than moving around.

If particulate pollution could be reduced throughout the week, and weekend photosynthetic activity levels maintained throughout, this would remove between 40 and 60 megatonnes of carbon dioxide from the atmosphere, sequestering it in biological materials. It will also increase agricultural productivity without increasing the area of ​​land used to grow crops.

“These findings have significant policy implications for European governments that are working on a variety of systems to capture and store about 500 megatonnes per year of carbon dioxide from the atmosphere,” Rosa concluded. “Our work shows that improving air quality can also help achieve climate goals.”

This work is part of Rosa’s comprehensive research programme, which aims to understand the agricultural challenges posed by climate change and evaluate different ways to improve agricultural sustainability. Rosa joins Carnegie in 2022 as a staff associate, a prestigious program designed to give early-career scholars the freedom and independence to pursue bold, unconventional research.

Since then, his efforts have included analyzes of irrigation strategies, soil moisture retention techniques, and water storage needs, as well as evaluating solutions to reduce the carbon footprint of fertilizer production and achieve net-zero emissions in agriculture.