- Adam, Ben;
- Western, Luke;
- Mühle, Jens;
- Choi, Haklim;
- Krummel, Paul;
- ODoherty, Simon;
- Young, Dickon;
- Stanley, Kieran;
- Fraser, Paul;
- Harth, Christina;
- Salameh, Peter;
- Weiss, Ray;
- Prinn, Ronald;
- Kim, Jooil;
- Park, Hyeri;
- Park, Sunyoung;
- Rigby, Matt
HFC-23 (trifluoromethane) is a potent greenhouse gas released to the atmosphere primarily as a by-product of HCFC-22 (chlorodifluoromethane) synthesis. Since 2020, the Kigali Amendment to the Montreal Protocol has required Parties to destroy their HFC-23 emissions to the extent possible. Here, we present updated HFC-23 emissions estimated from atmospheric observations. Globally, emissions fell to 14.0 ± 0.9 Gg yr-1 in 2023 from their maximum in 2019 of 17.3 ± 0.8 Gg yr-1, but remained five times higher than reported in 2021. Atmospheric observation-based emissions for eastern China, the worlds largest HCFC-22 producer, were also found to be substantially higher than 2020-2022 reported emissions. We estimate that potential HFC-23 sources not directly linked to HCFC-22 production explain only a minor, albeit highly uncertain, fraction of this discrepancy. Our findings suggest that HFC-23 emissions have not been destroyed to the extent reported by the Parties since the implementation of the Kigali Amendment.