Summary of the WMO Ozone and UV Bulletin No. 2 – September 2024

WMO Ozone and UV Bulletin, published by the World Meteorological Organization (WMO), provides updates on the state of the ozone layer and ultraviolet (UV) radiation in 2023 and highlights the role of the Montreal Protocol in protecting the environment and human health. Here’s a detailed breakdown of key points covered:

Ozone Layer Status in 2023

Ozone Recovery: The bulletin emphasizes that the Montreal Protocol, which successfully reduced ozone-depleting substances (ODS), has led to a gradual recovery of the ozone layer. The concentrations of harmful chemicals, such as chlorine and bromine, continue to decline.

Regional Ozone Patterns: The ozone column was slightly below climatological averages in certain regions, such as the Antarctic and northern mid-latitudes, while the tropics and the North Polar region showed higher-than-average values. This variability is influenced by atmospheric circulation patterns, such as the Brewer-Dobson circulation and Quasi-Biennial Oscillation (QBO), which modulate the transport of ozone between low and high latitudes.

Antarctic Ozone Hole: In 2023, the Antarctic ozone hole appeared earlier than usual and persisted into mid-December. Although the early onset deviated from recent trends, the hole's severity was reduced compared to previous years. Research continues into the factors influencing this variability, including atmospheric phenomena and volcanic activity.

Effects of the Hunga Tonga Eruption

The Hunga Tonga-Hunga Ha’apai volcanic eruption in January 2022 released vast amounts of water vapor into the atmosphere. This excess water contributed to localized ozone depletion, particularly near the Antarctic vortex's edge, but did not significantly accelerate overall ozone destruction.

Plastics and UV Radiation

Plastic Degradation: The report discusses how UV radiation accelerates the degradation of plastics, breaking them down into micro- and nanoplastics. Solar UV is the primary agent that initiates plastic fragmentation, which is further exacerbated by other environmental factors like heat and moisture.

The Montreal Protocol's Role: While primarily aimed at reducing UV radiation, the Montreal Protocol also indirectly slowed the rate of plastic fragmentation by reducing harmful UV levels. This has mitigated some environmental damage caused by plastics, though microplastics are now ubiquitous, with detrimental effects on ecosystems and human health.

Health Impacts of UV Radiation

Skin Cancer: UV radiation remains the leading cause of skin cancer globally, particularly among fair-skinned populations. With increasing UV levels and the projected impacts of climate change, preventative measures are urgently needed. 

Urban Planning and UV Exposure: The bulletin outlines a new urban UV model developed to quantify and reduce UV exposure in built environments. This model helps city planners design spaces that minimize harmful UV exposure by incorporating shading, vegetation, and protective structures.

Technological Advances and International Collaboration

Brewer Observations in South America: A major calibration campaign was conducted to restore Brewer spectrophotometer observations, which are vital for ozone monitoring in South America. This initiative brought together international experts and ensured that ozone data collection from the continent is up to global standards.

UV Calibration Campaigns: The third international solar UV radiometer calibration campaign (UVC-III) helped harmonize UV measurements worldwide. Accurate UV data is essential for assessing ozone recovery and providing reliable sun protection advice.

Global Cooperation and Future Directions

Ozone Research Managers' Meeting: The twelfth meeting of the Ozone Research Managers reviewed the current state of ozone science and monitoring. Key recommendations included improving global coverage of ozone-depleting substances, addressing gaps in observations, and strengthening international cooperation.

Quadrennial Ozone Symposium (QOS): The QOS 2024 meeting facilitated discussions among researchers about ozone trends, the impact of climate change, and the future of atmospheric monitoring. Highlights included early-career scientist awards and discussions on emerging research technologies.

Conclusion

WMO Ozone and UV Bulletin highlights the ongoing efforts and challenges in monitoring and protecting the ozone layer. While significant progress has been made thanks to international agreements like the Montreal Protocol, the variability in ozone recovery, emerging environmental threats like microplastics, and the growing risks of UV-related health issues emphasize the need for continued research, observation, and global cooperation.

Reference 

https://ozone.unep.org/sites/default/files/2023-06/Ozone_and_UV_Bulletin_1_en.pdf