Ozone Pollution Threatens Growth and Carbon Storage in Tropical Forests

Research reveals that ozone pollution is stunting tropical forest growth, especially in Asia, leading to a substantial reduction in their ability to absorb and store carbon. Factors like urbanisation, industrialisation, and fossil fuel burning contribute to rising ozone levels. The study highlights the critical role of air quality in mitigating climate change.

Ozone pollution is significantly stunting the growth of tropical forests, with particularly severe effects observed in Asia, where forests are losing nearly 11% of new growth, according to recent research.

Air quality will continue to play a critical, yet often overlooked role in how forests absorb and store carbon, said lead author Flossie Brown, a graduate of the University of Exeter.

Ozone, which protects us from harmful ultraviolet radiations in the upper atmosphere, is harmful closer to the ground. Formed by pollutants from human activities in sunlight, it stunts new forest growth and hampers carbon capture.

Urbanisation, industrialisation, and fossil fuel burning increase 'precursor' gases such as nitrogen oxides, which form ozone, found the research team.

The study, published in Nature Geoscience, estimates that ground-level ozone stunts new tropical forest growth by over 5%, equaling 290 million tonnes of uncaptured carbon annually since 2000.

Tropical forests are vital 'carbon sinks' capturing and storing carbon dioxide, a significant greenhouse gas driving climate change.

Geographical variation shows a decrease ranging from 1.5% in Central Africa to 10.9% in Asian tropical forests, authors emphasize.

Lead author Alexander Cheesman from the University of Exeter said ozone has prevented the capture of 290 million tonnes of carbon yearly since 2000, amounting to a 17% reduction in carbon removal.

Researchers conducted experiments to measure ozone's effects on various tropical tree species, integrating the results into a computer model of global vegetation.

Brown warns that a warming climate will likely elevate ozone levels across the tropics, disproportionately impacting areas critical for forest restoration and climate change mitigation.