The workshop brought together representatives from international organizations, research institutions, government agencies and the private sector to discuss approaches for optimizing the G3W observation network across land, ocean, atmosphere and cryosphere domains. The goal is to build a cost-efficient, interoperable network that integrates surface-based and space-based observations under the WMO Integrated Global Observing System (WIGOS).
Towards an optimized global observing system
Discussions centred on harmonizing monitoring approaches to support high-quality, operational data products. Participants explored multiple methodologies - from model intercomparisons and footprint analysis to Observing System Simulation Experiments (OSSEs) - to inform the design of surface and ocean observation networks.
A key outcome was the recommendation for G3W to define specific observation requirements under the Rolling Review of Requirements process. These requirements will guide the integration of diverse observing systems, ensuring that data meet the accuracy and resolution needs of operational products such as monthly 1°×1° gridded fields of carbon dioxide (CO2) and methane (CH4) fluxes.
Strengthening collaboration and transparency
Participants emphasized the importance of close collaboration among modelling teams and observing networks. Transparent model intercomparison exercises were identified as essential tools for locating observational gaps and improving atmospheric inversion systems. Future activities will focus on developing metrics to evaluate and rank model performance, with a dedicated G3W modelling workshop planned for 2026.
The meeting also highlighted the need for a balanced integration of surface and satellite observations. Rather than competing, these data sources were recognized as complementary - ground-based measurements enhance satellite validation and fill spatial gaps, while satellite data extend global coverage. Effective coordination between surface and satellite providers will be vital to ensure robust calibration and validation of satellite observations.
Enhancing ocean observations
Given the critical role of oceans in the global carbon cycle, participants called for renewed investment in surface ocean CO2 observations. Short-term actions include restoring shipboard and mooring-based pCO2 measurements to pre-pandemic levels and supporting the Surface Ocean CO2 Atlas (SOCAT) through sustained, multinational funding.
Medium-term goals involve broadening observing capacity and operationalizing data products, while long-term objectives include integrating atmospheric CO2 observations from ships and deep ocean profiling for consistent reanalysis.
Sustaining networks for the future
Participants underscored the importance of sustaining observational networks through clear financial and governance mechanisms. As G3W transitions from research to operations, long-term stability and international coordination will be key to ensuring reliable global GHG monitoring.
The workshop concluded with a call for continued collaboration among partners, leveraging community expertise and shared infrastructure to build a robust, efficient, and sustainable global GHG observation system. The outcomes will feed into the 2027 Observing System Impact Workshop, broadening its scope beyond weather prediction to include greenhouse gas monitoring.
About the Global Greenhouse Gas Watch (G3W)
Launched by WMO in 2023, the Global Greenhouse Gas Watch (G3W) coordinates international efforts to provide authoritative, operational information on greenhouse gas net fluxes and concentrations. By integrating observations from land, ocean, and atmospheric systems, G3W supports global climate monitoring and mitigation strategies.
