World Meteorological Day 2026, celebrated under the theme Observing Today, Protecting Tomorrow, highlights the essential role of robust environmental monitoring in safeguarding the planet’s future. It’s an opportunity to highlight how international chemical governance contributes to protecting the atmosphere and climate system - not only through regulation, but through the science and monitoring frameworks that identify trends, detect unexplained emissions, and guide global action.

While the Basel, Rotterdam and Stockholm (BRS) conventions address hazardous chemicals - including persistent organic pollutants (POPs), whose long-range environmental transport links chemical pollution with atmospheric processes and global environmental change - the atmospheric monitoring networks established under Vienna Convention for the Protection of the Ozone Layer and its Montreal Protocol on Substances that Deplete the Ozone Layer stand alongside the BRS conventions addressing ozone-depleting substances (ODS) and other controlled chemicals affecting the ozone layer and climate. This coordinated global action - spanning global monitoring networks - protects the atmosphere and human health.

The BRS conventions protect human health and the environment from hazardous chemicals and wastes across their life cycles. Their mandates increasingly intersect with broader environmental challenges, including biodiversity loss and climate change. At the 2025 meeting of the Conference of the Parties, Parties to the Stockholm Convention took further steps to strengthen global protection against POPs, including the listing of long‑chain perfluorocarboxylic acids (LC‑PFCAs), a subgroup of PFAS often referred to as “forever chemicals” due to their extreme environmental persistence. This decision represents the fourth group of PFAS to be listed under the Convention, reflecting growing global efforts to address this class of highly persistent substances.

Through its atmospheric networks and expert panels, the Montreal Protocol has repeatedly demonstrated its unique ability to identify discrepancies between reported and observed emissions - such as unexpected emissions of CFC11 and HFC23 that are not aligned with emissions to be derived from national reporting. These discoveries reinforce not only the importance of monitoring, but the critical role of science in ensuring the achievement of the objectives of the Protocol and spurring corrective action. This “measure-and-respond” model is one of the most successful examples of environmental monitoring driving real-world policy outcomes.

The BRS Secretariat and the Ozone Secretariat also continue to strengthen collaboration in their efforts to address hazardous and illegally traded substances. Through this cooperation, the Secretariats exchange information and coordinate actions to combat, an international partnership aimed at enhancing the capacity of customs and border officers to identify, control and intercept illicit shipments of hazardous chemicals, ODS and other regulated materials. The Basel Convention also provides comprehensive technical guidelines that apply to the destruction methods commonly used for substances controlled under the Montreal Protocol. Green Customs Initiative, an international partnership aimed at enhancing the capacity of customs and border officers to identify, control and intercept illicit shipments of hazardous chemicals, ODS and other regulated materials. The Basel Convention also provides comprehensive technical guidelines that apply to the destruction methods commonly used for substances controlled under the Montreal Protocol.

While customs-based enforcement may address illegal shipments, the Montreal Protocol’s system of atmospheric monitoring acts as an independent check - detecting unusual or rising emissions that may indicate illegal production, or under-reporting or non-reporting. This dual system of on-the-ground enforcement and atmospheric surveillance strengthens global compliance and integrity.

Through shared training programmes, information tools, and coordinated enforcement efforts, the initiative supports countries in implementing and enforcing their obligations under multilateral environmental agreements. Recent work by the Secretariats has also highlighted these connections. An exploratory study on the interlinkages between the Montreal Protocol and the Basel, Rotterdam and Stockholm conventions (UNEP/CHW.17/INF/59) underscores opportunities for enhanced cooperation in areas such as hazardous chemicals management, environmentally sound waste management, and enforcement against illegal trade.

The partnership between the BRS Conventions and the Montreal Protocol also highlights the importance of linking sound chemical management with atmospheric monitoring. By supporting the detection of pollutants transported through the atmosphere — including POPs monitored under the Stockholm Convention’s Global Monitoring Plan and controlled substances monitored under the Montreal Protocol’s atmospheric networks — these efforts strengthen the scientific basis for evaluating the effectiveness of global environmental agreements and for informing policies that protect air quality, ecosystems and climate stability.

As we mark World Meteorological Day 2026, the message is clear: Protecting tomorrow depends on what we observe and how we act today.