Carbon dioxide (CO₂) and methane (CH₄) released into the atmosphere by human activity are major contributors to the presence of greenhouse gases (GHGs), driving climate change. Field-deployable spectroscopes can help identify sources and discriminate between human and natural emissions for these by analysing the ratios of CO₂ and CH₄ isotopes present. However, these instruments require calibration with gases with measurement traceability and precisely known isotope compositions which are currently lacking, compromising the comparability of global observations.

The project has provided improved CO₂, and the first ever, CH₄ reference materials linked to the SI through international isotope ratio scales. Validation routines and traceability chains for spectroscopic techniques have also been developed to allow state-of-the-art measurements to be made in the field. At the end of the project in 2023 the improved discrimination between natural and manmade sources of GHGs will aid governmental agencies to better attribute emission sources, help demonstrate compliance to national reduction targets and enhance the effectiveness of future abatement strategies.

This project builds on from EMPIR project 16ENV06 SIRS  and EMPIR project 21GRD04 isoMET builds on this work.