In a new study published in the Proceedings of the National Academy of Sciences, we investigated the sources of discrepancy between HFC emissions reported to the UNFCCC and “top-down” emissions inferred from atmospheric observations. We found that the majority of the gap can be attributed to non-reporting or developing nations. But interestingly, we found that reports from developed (or Annex 1 nations) were accurate when looking at HFCs in aggregate but were significantly over or under-reported for individual species. This has significant implications for improving the methodologies used to inventory HFC emissions. A summary of the findings can be found in a press release from the University of Bristol.