With the world struggling to cope with the growing climate crisis, cities have become both significant emitters and key actors in the global fight against greenhouse gas (GHG) emissions. Cities, which cover a mere percentage of the Earth's surface, account for about 70% of global GHG emissions. With an awareness of the important role of cities in managing climate change, the Integrated Global Greenhouse Gas Information System (IG3IS) and the Integrated Carbon Observation System (ICOS) Cities Project jointly hosted the Urban Greenhouse Gas Conference and Stakeholder Summit 2025 at the World Meteorological Organization (WMO) headquarters in Geneva between 7–9 April.

The summit, which was among the most important international events concentrating on GHG monitoring and reduction in cities, united top scientists, city planners, policymakers, and stakeholders from all over the globe. The main goal of the conference was to facilitate discussions, exchange the newest scientific discoveries, and finalize the draft IG3IS Urban Good Practice Guidelines — an important document that specifies tested ways to monitor and minimize greenhouse gas emissions in cities.

The ceremony was a significant milestone in the WMO's 75th anniversary celebrations. With the theme "Science for Action," the anniversary emphasizes the organization's vision to use science to promote practical and effective climate action. "This year, WMO is celebrating its 75th anniversary as a UN specialized agency with the theme of Science for Action, which captures the spirit of WMO's work," stated Johan Stander, Senior Director of the WMO Services Department. The Urban Greenhouse Gas Conference and Stakeholder Summit is a great testament to the WMO cooperating with partners in order to gather world-leading researchers and influential decision-makers together in order to reinforce one another's mission to advance people's lives across the globe.

As cities compete to fulfill ambitious climate targets, the need for high-quality and high-resolution greenhouse gas emissions data has never been higher. Precise GHG data is critical for planning, executing, and evaluating mitigation measures. During the three-day conference, attendees learned about cutting-edge approaches to enhancing urban GHG tracking. One of the main discourses concerned combining atmospheric observations with activity data — a dual approach that markedly improves the precision of emissions estimation.

The conference also introduced 31 different techniques documented in the IG3IS Urban Good Practice Guidelines. These techniques offer a broad spectrum of solutions, making them adaptable to a variety of city needs and user groups. Such a diverse range of approaches ensures that cities, regardless of their size, geography, or economic status, can find relevant and effective tools to track and reduce emissions.

Along with the scientific and technological debates, the summit highlighted the need to make these approaches available to non-technical stakeholders. Most of the people who are tasked with putting into practice and overseeing GHG reduction measures in cities are not scientists but are crucial to climate action. Acknowledging this, the last day of the summit was devoted to stakeholder engagement. Through panel debates and interactive dialogue, cities introduced their needs, knowledge gaps, and engagement techniques, ensuring the tools being crafted are practical as well as deployable.

One of the highlights of the conference was the IG3IS animation "Monitoring the Atmosphere to Reduce Urban Greenhouse Gas Emissions." The animation did a great job of illustrating how advances in high-resolution atmospheric monitoring, coupled with sophisticated modelling techniques, can yield precise and timely emissions data. This is a game-changer for urban planning and decision-making, allowing cities to adapt their mitigation efforts more specifically and effectively.

As the summit closed, it was evident that the way to a global climate target goes through the cities. Through better monitoring, enhanced cooperation among scientists and stakeholders, and more accessibility of GHG data and tools, urban areas can show the way for the global climate response. The Urban Greenhouse Gas Conference and Stakeholder Summit 2025 was a living proof of this common commitment — where science and action meet, and innovation transforms.