We are developing a comprehensive next-generation greenhouse gas (GHG) calibration system capable of extending SI traceability to global satellite remote sensing and terrestrial remote sensing platforms across all relevant spatial scales. We are aiming to achieve this by directly linking molecular spectroscopy to the SI and by exploiting this link to develop frequency comb remote sensing instruments with unprecedented open path accuracy. This will allow direct calibration of GHG remote sensing satellites and will provide the critical methane and carbon dioxide metrology necessary to monitor the natural background and anthropogenic sources across the globe, limit unintended emissions, enrich public safety, and guide climate policy.