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Ozone Pollution Threatens Tropical Forests and Carbon Storage
Context:
A new study published in Nature Geoscience shows that ozone pollution severely affects tropical forests, causing them to lose about 300 million tonnes of carbon annually.
More on News:
- Tropical forests act as crucial “carbon sinks,” capturing and storing carbon dioxide that contributes to global warming.
- Ozone concentrations are expected to rise due to increased precursor emissions and altered atmospheric chemistry worsening the impact on tropical forests.
Ozone is an odourless, colourless gas made of three oxygen atoms (O3). It exists naturally in both the Earth’s upper atmosphere (stratosphere) and at ground level (troposphere).
Ozone Levels:
- Stratospheric Ozone: Protects Earth from harmful UV radiation and is a success of environmental action.
- Ground-Level Ozone: Formed by pollutants and sunlight, interferes with plants’ ability to absorb carbon dioxide and is harmful to human health.
Key Highlights:
- The study found that ozone pollution decreases yearly growth in these forests by an average of 5.1%, with some regions experiencing even greater impacts, such as Asia, where it reaches 10.9%.
- Ground-level ozone has prevented the capture of 290 million tonnes of carbon per year since 2000. This has resulted in a cumulative 17% reduction in carbon removal by tropical forests this century.
- Urbanisation, industrialisation, fossil fuel burning, and fires have increased the precursor molecules like nitrogen oxides that form ozone.
- Areas of current and future forest restoration, critical for climate change mitigation, are disproportionately affected by elevated ozone.
- The study underscores the need for better environmental protection to reduce ground-level ozone and improve air quality, thereby supporting tropical forest health and climate change mitigation efforts.
Ozone Depletion:
- Some compounds known as ozone-depleting substances (ODS) release chlorine or bromine which in the presence of UV radiation contribute to ozone depletion in the Stratosphere.
- Sources: Chlorofluorocarbons (CFCs), Halons, Hydrochlorofluorocarbons (HCFCs), carbon tetrachloride, methyl chloroform, and methyl bromide.
Measures to regulate Ozone Depleting Substances:
- Vienna Convention for the Protection of the Ozone Layer:
- Signed in 1985
- It was the first international agreement dedicated to the protection of the ozone layer.
- Montreal Protocol on Ozone-Depleting substances:
- Gradually eliminating the production and consumption of ozone-depleting substances to limit their damage to the earth’s ozone layer.
- Hydrochlorofluorocarbons (HCFCs) are being phased out under the Montreal Protocol since they deplete the ozone layer.
- The Montreal Protocol was signed by 197 countries – the first treaty in the history of the United Nations to achieve universal ratification.