G3W Overview
The Global Greenhouse Gas Watch (hereafter G3W) aims at providing global products of monthly net fluxes of CO2, CH4, and N2O with 1x1 degree resolution, aiming to improve sustainability and increasing data availability for reliable GHGs monitoring.
In 2023, the 19th World Meteorological Congress (Cg-19, Resolution 5) approved a concept note for the G3W, which aims to support WMO Members' decision-making in climate mitigation actions to implement the Paris Agreement by providing timely information on the net fluxes of the main greenhouse gases.
This concept has been developed in a close collaboration between WMO and partner organizations dealing with greenhouse gases and carbon cycle. Based on this concept note the community under WMO coordination developed an Implementation Plan. In 2024, INFCOM-3 approved the G3W Implementation Plan (IP), and the 78th Executive Council (EC-78) endorsed the plan to officially commence its Pre-Operational Phase (IPP) for the period 2024-2027.
The G3W fills critical information gaps and provides an integrated, operational framework that brings together all observing systems, as well as modelling and data assimilation capabilities in relation to greenhouse gas monitoring. It is expected that operationalization of the greenhouse gas monitoring will improve its sustainability and data availability for multiple potential applications.
WMO has a long-term experience in coordinating provisions of the meteorological forecasts across the globe where outputs of several global modelling Numerical Weather Prediction Centers (NWP) can be used to understand the weather at any place on the planet.
Similarly, the ambition of G3W is to ensure that global distribution of net fluxes and concentrations of greenhouse gases is available at any point on the planet close to real time, representing in this way “Carbon Weather”.
As a WMO-coordinated initiative considering that international cooperation is crucial, G3W remains apolitical as its ambition is to create a technical framework for member countries to cooperate on production of the Greenhouse Gas (GHG) data products. The global GHG monitoring infrastructure based on established methodology and standardized protocols will provide a wealth of quantitative data to help improve our understanding of GHG cycles. The G3W will consolidate existing measurement and analysis capabilities to provide estimates of total net greenhouse gas fluxes - carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) - on a global scale, at a relatively high resolution in space and time, on a monthly basis. Increasing abundances of these gases in the atmosphere are the dominant cause of the observed climate change and related impacts according to studies from the Intergovernmental Panel on Climate Change.
Improved understanding of the fluxes will offer valuable data to countries for better monitoring of greenhouse gases, allow better prediction of their long-term future climate trajectories, with potentially strong implications for the required mitigation activities here and now and support informed decision-making for climate-related actions.
This system will establish a technical framework for operationalization of greenhouse gas observations and implementation of the modelling activities and international data exchange required to produce a 100x100 km grid or 1x1° data products that would allow for early detection of significant changes in global greenhouse gas levels and help to identify geographical dynamics as well as potential feedbacks in the Earth System.
It is anticipated that ongoing and new research to develop capabilities to further separate these net fluxes into source-apportioned emissions will lead to additional operational products in the future. Per WMO's data policy and in the interest of maintaining transparency, the data are expected to be made available to all users worldwide on a free and unrestricted basis.
However, the quality of the G3W products will depend on the quality and completeness of the data it receives. Therefore, it is essential to address existing data gaps in critical geographical regions and enhance the ground-based observing network, particularly over oceans, to ensure comprehensive and accurate monitoring.
Foundation of G3W
The Paris Agreement, adopted in 2015 under the United Nations Framework Convention on Climate Change (UNFCCC), is a landmark international treaty to combat climate change. One of its central objectives is to limit the global average temperature rise to well below 2°C above pre-industrial levels, with efforts to limit the increase to 1.5°C. Achieving this target requires global cooperation and significant reductions in greenhouse gas emissions, along with measures to enhance resilience and support climate adaptation.
During the twenty-seventh Conference of the Parties (COP27 in Sharm El Sheikh, 6th–20th November 2022), the Parties recognized that “{…} limiting global warming to 1.5°C requires rapid, deep and sustained reductions in global greenhouse gas emissions of 43% by 2030 relative to the 2019 level;”. It further “Emphasizes {…} the need to enhance coordination of activities by the systematic observation community and the ability to provide useful and actionable climate information for mitigation, adaptation and early warning systems, as well as information to enable understanding of adaptation limits and of attribution of extreme events”. Access to improved harmonized information on the concentrations and fluxes of GHGs, in part already collected by existing infrastructures, is needed to help countries to establish their commitments and to monitor progress toward meeting emission reductions targets.
The 1st Global Stocktake (GST-1) presented at COP28, already made use of some of the systems that will be foundational for G3W.
Implementation timeline
The G3W Implementation Plan (G3W-IP hereafter) is organized in a way that allows for step-wise implementation with the actions within the current financial period (2024-2027) focusing on the Implementation Pre-operational Phase (G3W-IPP). The G3W Initial Operational Phase (G3W-IOP) is foreseen in the next financial period (2028-2031), including the consolidation of the G3W systems configuration for the 2nd Global Stocktake(GST-2) from 2026 to 2028.
The evolution of G3W beyond 2032 is to support the Paris Agreement Enhanced Transparency Framework (ETF), which will provide progress assessments towards the climate neutrality goal and ambition. G3W will aim to provide actionable information assisting the countries in their Long-Term Low greenhouse gas Emission Development Strategies (LT-LEDS), which provide the long-term horizon for the Nationally Determined Contributions (NDCs).
This phase of the G3W development is labelled the Enhanced Operational Phase (G3W-EOP). It aims to integrate maturing technologies from satellite remote sensing, ground-based networks, conventional, and data-driven modelling approaches stemming from artificial intelligence, with the goal of reducing uncertainties and increasing the reliability of the GHG monitoring systems.
G3W is moving forward
The initiative has now entered the pre-operational phase, requiring the establishment of foundations for full operational implementation. To drive this process forward, the Joint Advisory Group on G3W, along with three dedicated Task Teams, has been established. Priority activities have been identified in the areas of observations, modeling, and data, with a focus on integrating these key components into the WMO Information System (WIS) and the WMO Integrated Processing and Prediction System (WIPPS).
These topics have been central to discussions during the G3W Global Data Providers workshop held from the 5th to the 7th of March 2025.
The overarching goal is to develop a system that aligns with the WMO Unified Data Policy, facilitating seamless international data exchange. Recognizing the complexity of this endeavor—particularly given that many relevant data sources exist outside National Meteorological Services—strong collaboration with the research community will be essential to the success of G3W.
