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Greenhouse gas emissions, greenhouse gas concentrations and global mean temperature all continue to rise, and in order to stay within the temperature limits stipulated in the text of the Paris Agreement, mitigation action is becoming increasingly urgent However, the fact that we cannot quantitatively and reliably predict future GHG concentrations and therefore climate scenarios from assumed future emission pathways is a complicating factor when designing mitigation action. Even more problematic is the assessment the impact or effectiveness of many current or proposed mitigation activities, since it often has to be based on indirect measures such as avoided emissions with respect to a hypothetical baseline, or carbon stored, e.g. in the land or ocean biosphere, neither of which can be directly linked to atmospheric concentrations. In order to provide robust, actionable data that will help Parties to the UNFCCC and other stakeholder design and develop mitigation action and monitor its effectiveness, the World Meteorological Congress in May 2023 endorsed the Global Greenhouse Gas Watch (G3W) as an internationally coordinated framework to provide near-real time GHG (CO2, CH4 and N2O) flux estimates based on atmospheric modelling and atmospheric observations. At COP28 in Dubai, the G3W was formally recognized by the Subsidiary Body for Scientific and Technological Advice (SBSTA-59) to the UNFCCC. Currently a G3W implementation plan is in development, with the aim of submitting it for approval by the WMO Executive Council by mid-2024. Some of the key elements of the plan are a significant strengthening of the global GHG observing capabilities, improved near-real time exchange of both observational data and flux estimates, and routine intercomparision of model output among all participating flux estimation centers. The presentation will introduce the overall G3W development timeline which aims for a full operational capability to be ready for the Second Global Stocktake in 2027-28, with the main focus on the near-time activities planned for 2024-25.
Balsamo et al. (Mon,) studied this question.