Role of the Orbiting Carbon Observatory Missions (OCO-2 and OCO-3) Towards an Integrated Global Greenhouse Gas Monitoring System

We are moving into a new era of open, coordinated, and integrated global greenhouse gas monitoring to provide robust, timely and authoritative information to the global community. This is evident from the recent launch of the US Federal Strategy to Advance an Integrated U.S. Greenhouse Gas Monitoring and Information System and the World Meteorological Organization's new Global Greenhouse Gas Watch (GGGW) initiative. Such efforts while ambitious, are not insurmountable but require careful consideration and understanding of our current capabilities and limitations. In this presentation, we will review the capabilities of NASA’s Orbiting Carbon Observatory -2 and -3 (OCO-2 and OCO-3) missions, which are anchored to a network of ground-based instruments (Total Carbon Column Observing Network, TCCON). I will use a series of examples to demonstrate how OCO-2 and OCO-3 can respond to the needs of these greenhouse gas monitoring initiatives. These examples include CO₂ emission estimates from regional to facility-scales as well as quantifying the response of natural terrestrial and oceanic sinks to climate variability and climate extremes. Furthermore, through these examples, I will highlight: (a) the value of the stable, long-term, and high-quality data record from the OCO missions, and (b) the value of a diverse observing portfolio, i.e., a combination of space-based remote sensing, ground-based remote sensing, airborne and in situ networks, for monitoring the response of the Earth system to a changing climate. I will conclude the presentation with a summary of the existing capabilities and limitations of our current observing portfolio, lessons learnt from operating OCO-2/3 and recommendations regarding the design of a comprehensive, integrated observing system to support operational monitoring and verification of greenhouse gas emissions for all nations and communities, including the Parties of the Paris Agreement.